CA1078188A - Volatile liquid supply equipment and processes and apparatus for introducing volatile cross-linking agents into polyolefin compounds and for the extrusion of cross-linkage polyolefin compounds - Google Patents

Abstract

Abstract of the Disclosure In accordance with an exemplary embodiment of the instant invention, a volatile cross-linking agent such as liquid peroxide is introduced, at ambient temperature and under atmospheric pressure directly into the input of an extruder at the same pressure as a poly-olefin compound to be cross-linked. The resulting compounds are put under pressure within the extruder as the temperature increases so that the mixture reaches its definitive shape at the extruder output and may be fed directly into a hot cross-linking enclosure which is maintained under pressure. The peroxide is thus incorporated in a single operation permitting complete control of the ingredients mix-ed and allowing perfect homogenization of the mixture while defusion and consequent loss of the highly volatile peroxide are avoided.
The system for introducing the highly volatile cross-linking agent includes a peroxide storage tank, a filling pump, a feed vessel, an incremental feed pump with a pressure meter, a flow meter and numerous safety features. These elements control the flow, temperature and ambient conditions of the cross-linking agent feed system within a controlled environment to ensure the safe and precise handling of a highly volatile liquid while at the same time controlling the feeding of the liquid as a function of the material processed by the extruder so that the percentage of the cross-linking agent inserted at the input to the extruder remains at a constant, predetermined percentage, regardless of extruder speed variations. Additionally, various addi-tives which are soluble in the volatile cross-linking agent may be introduced within the feed system therefor in sufficient amounts for effecting protection of the resulting polymer without altering the efficiency of the feed system or that of the additive so that the entire process may be carried out at the processing site without initial preparation of various mixtures to be further processed.

Description

This invention relates to volatile liquid injection systems and to processes and apparatus for the preparation of plastomer compounds and more particularly volatile liquid supply equipment and to production processes and apparatus for intro-ducing volatile cross-linking agents which may be flammable into cross-linkable polyolefin compounds and Eor the continuous extrusion of cross-linkable polyolefin compounds with a maln-tenance of safe operating conditions.
The cross-linking processes assoc:La~ed wlth plastomer compounds from polyolefin polymers such as polyethylenes or the like is well known and is disclosed in U.S. Patent No. 2,628,214 entitled Curing of Polyethylenes as issued to Pickney and Wiley on February 10, 1953 and U.S. Patent ~o. 2,528~523 entitled -~
Process for Extruding And Insolubilizlng Polymers of Ethylene as issued to R.E. Kent on November 7, 1950. Typically, these ,, processes provide for the introduction of organic peroxides by curing at elevated temperatures, on the order of 160 to 250C., ~-under pressure and result in products which are highly advanta-geous and may be emplo~ed to form insulating or scmiconductive layers for cable and the like if the same are produced with ~ ~ -: .
extruders. Polyolefin compounds prepared according to the - -teachings of the prior art were required to be prepared so that the same could accept the cross-linking agent, a protective agent, and any filler materials to be employed in a suitable mixture within a well defined, narrow temperature zone. This zone, for example, in the case of a low density polyethylene and under favourable mixing conditions, would be located between ` 105 `and 135C. The higher temperature within this range is dictated by the cross-linking agent while the lower temperature : 30 is mandated, in the case of polyethylene, by the viscosity of .

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the ~atter in :itS molten stat~. The compounds thus prepare~
would then be cross-linked at the extruder output by passing directly into a chamber under pressure of water vapor or super heated water at elevated temperatures of approximately 180 to 250C. ~lternatively, introduction of the cross-linking agent could occur within the extruder screw output zone ~ust prior to a penetration oE the mixture into the extruder head; however, mixing here occurs within a zone where the polyolefin compound is sub~ected to very high pressure rendering the introduction of the cross-linking agent highly impractical and resulting in a mixture which is not homogeneoua.
In practical application within the industry, the preparatory operations for polyolefin compounds capable of being cross-linked were limited to a choice of organic peroxides which were suitable for the cross-linking of such compounds wherein suitability limited the choice of cross-linking agents to organic compounds displaying low volatility at the temperatures employed during the mixing operations. Therefore, certain highly volatile, flammable, liquid organic peroxides ~hich en~oy current use as cross-linking agents for silicone rubber and other synthetic elastomers could not be practically employed under industrial conditions for the cross-linking of polyolefin com-pounds and in particular, of polyethylene compounds because of the required high temperatures which occur during processing.
This form of exclusion extended to tertiary butyl peroxide or di-t butyl peroxide DTBP, ~hose boiling point is approximately 110 C at 760 mm of mercury pressure despite the fact that DTBP is a highly advantageous cross-linking agent because it exhibits cost advantages as well as enabling the fabrication of cross-linked polyethylenes with low photo degradability due to anabsence of aromatic cetones. Furthermore, when a liquid ~8~L 518 peroxide is employed as a cross-linking agent for polyolefin compounds, at ambient temperatures and pressures, the peroxide may be introduced in a single operation at, for example, the extruder input, and avoids the need for prior preparation of the organic compound in the manner described above. In addition, such use of a liquid peroxide permlts complete control of the mixing of the ingredients at a single location prior to further processing and results in a highly homogeneous mixture which was not available with prior art techniques.
Therefore, it is an object of this invention to provide processes and apparatus for introducing volatile and/or flammable cross-linking agents into polyolefin compounds.
It is a further object of this instant invention to provide processes and apparatus for the continuous extrusion of cross-linkable polyolefin compounds employing highly volatîle cross-linking agents.
It is an additional object of the present invention to provide processes and apparatus enabling the practical use of liquid perox;des as cross-linking agents for polyolefin com-.,.
pounds.
It is another ob~ect of the instant invention to provideprocesses and apparatus for producing cross-linkable polyolefin compounds by mixing volatile cross-linking agents directly at the extruder input while maintaining processing conditions at a - ~ ... .
safe level which is continuously monitored.
It is an additional object of the present invention to provide apparatus for sa~ely conveying liquid peroxîde to a mixing point under conditions where the amount o~ liquid peroxide conveyed is precisely metered and conditions within the system are constantly monitored to ensure the safe operation thereof.

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It is a further ob~ect oE the present invention to provide processes and apparatus for automatically conveying the peroxide to a mixing point at a rate which is governed by the material processed from that mixing point under conditions where safety conditions are monitored throughout the system and upon failure of a signiflcant condition, the conveyi~g system is automatically shut down and an alarm conclition initiated.
Other ob~ects and advantages of the lnvention will be-come clear from the following detal.led description of an examplaryembodiment thereof, and th.e novel features will be particularly .
pointed out in connection with. the appended claims. ~1.
In accordance with an exemplary embodiment of the ~ :
instant invention, a volatile cross-linking agent such as liquid peroxide is introduced, at ambient temperature and under atmospheric pressure directly into the input of an extruder at the same pressure as the polyolefin compound to be cross-linked, the resulting compounds being put under pressure within the extruder as the temperature lncreases so that it reaches its definitive shape at the extruder output and may be fed directly into a hot cross-linking enclosure which is maintained under ~ -pressure 50 that the peroxide-is incorporated in a single operation permitting complete control of the ingredients mixed and allowing perfect homogenization of the mixture while defusion and consequent loss of the highly volatile peroxide are avoided~
The system for introducing the highly volatile cross-linking agent includes a peroxide storage tank, a filling pump, a feed vessel, and incremental feed pump with. a pressure gauge, a flow meter and numerous safety features which control the flow, temperature and ambient conditions of the cross-linking agent feed system within a controlled environment to ensure the safe and precise hanclllng Oe a highly volatile liquid while at the same time controlling the feeding of the liquid as a function : of the material processed by the extruder so that the percentage of the cross-linking agent inserted at the input to the extruder '-remains at a constant, predetermined percentage, regardless of extruder speed variations. Additionally, as shall be seen hereinafter, various additives which are soluble in the volatlle cross-linking agent may be introduced within the feed system therefor in sufficient amounts Eor effecting protection Oe the resulting polymer without altering the eEfic:Lency of the feed system or that of the additive so that the entire proce~s. may be carried out at the processing site w-ithout initial preparation ::
of various mixtures to be further processed. Additional objects Oe the present invention will be apparent from the operation of the embodiment of the instant invention wkich is disclosed herein and the operation of the disclosed embodiment of the . .~
present invention will be clearly understood from the following ;
description and the accompanying drawings in which: ;
Figure 1 is a pictorial view illustrating exemplary ,~.
20 continuous extrusion techniques for cross-linkable polyolefin :
compounds in accordance with the teachings of the present invention together with housings for the volatile cross-linking agent feed system and the electrical control and alarm equipment therefor;
Figure 2 is a highly generalized block diagram ~:
schematically illustrating the details of the volatile cross- :
linking agent feed system for supplying the ~olatile cross-linking agent in the manner illustrated in Figure l; and Figures 3A and 3B depict a schematic diagram illustra- .
ting the details of the volatile cross-linking agent feed system -. .
and the electr~cal control and alarm equipment for the exemplary i _ 5 _ .. -.:
: . . .:

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continuous extrusion embodiment of the invention illustrated in Figure 1. ~s Figures 3A and 3B connect from left to right to depict a single schematic, these figures are frequently referred to in combination as Figure 3.
Referring now to Figure 1, there is sho~n a pictorial view of an exemplary continuous extrusion technique for cross linkable polyolefin compounds in accordance with the teachings of the present invention together with housings for the volatile cross-linking agent feed system and the electrical control and alarm equipment therefor. The apparatus illustrated ln Figure 1 comprises an electrical control and alarm cabinet 1, a peroxide feed cabinet 2, and extruder 3, and a continuous vulcanization tube 4. The electrical control and alarm cabinet 1~ as shall be seen in greater detail in conjunction with Figure 3 includes all logic, control, alarm, condition indicia, connection terminal boards and other electrical apparatus employed or the control, maintenance and monitoring of the pe~oxide feed system within cabinet 2 while all electrical moto~s which are disposed within -the cabinet per se are of the explosion proof type or are connected to inherently safe supplies. ~11 feed through conduits and connectors intermediate the two cabinets are provided with seal proof gaskets and all electrical connec-tions are made, wherever possible, within terminal boards mounted within the electrical cabinet 1 so that, in essence, all circuitry required for the peroxide feed system is present within electrical cabinet 1 except where the presence of a specific drive or motor system within peroxide feed cabinet 2 is absolutely necessary such as in the case of a motor or the like and under these circumstances such motor i5 of an explosion proof construction. On the face 5 of the electrical control and alarm cabinet 1 are located a plurality of control, monitoring , ' ~"

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and alarm indicia to provide an operator with immediate visual appraisal capabilities of the present operation of the system as well as records regarding the past history thereof. In addition, any alarm condition of note is further accompanied by the sounding of a siren or horn so that both the audible and visual senses are stimulated should an alarm condition result. ~lore particularly, the electrical control and alarm cabinet 1 is provided with two sets of visual condition lndicating devices 6 ~ 7 to provide the operator with immed:Late indication6 which are advisory of the operational conditions within the system. ~ltho~lgh the nature of these indicia will become apparent in con~unction with Figure 3, it should here be appreciated that condition indicia 7 ma~ take the form of ten alphameric display panels located in a side by side manner which are selectively illuminated by the system should the condition to which they are assigned occur within the system.
Certain of these indicia merely are advisory of normal operating conditions while others are indicative of a condition which will cause system operation to terminate if the same are not quickly corrected. The conditions for which an alphameric display panel is provided within the condition indicia array 7 are as follows;

Maximum Flow Empty Hopper Dangerous Flow Extruder Sync Minimum Flow Line Sync Maximum Level Heat Rise Minimum Level Leak ~ :
In addition, the condition indicia 6 comprise a plurality of colored panels which are selectively enabled in conJunction with selected ones of the condition indicia in array 7 to indicate -~
normal operating conditions, abnormal operating conditions or the onset of dangerous conditions which, as will be seen below, ~ :
are accompanied by a shutting down of the system. The colored panels associated with the condition indicia 6 are nor~ally : ~ 7 -78~88 selectively illu~inated in conjunction with the alphameric panels within the condition indicia array 7 so that the operator is apprised both as to the urgency of the cond~tion which has occurred and its precise nature. The condition indicia 6 may typically com-prise five differently colored panels, such as red, orange, green, blue and white wherein the wh~te, blue and green panels are indicative of normal system operation, the orange panel 1 indicative of an abnormal condition while the red panel is indicative of a dangerous condition which may cause system shut down to occur. Addltionally, while the white, blue and green panels will be continuously illuminated during normal forms of operation, the illumination of the orange and red panels occurs on an intermittent or flashing basis and is accompanied by the sounding of a horn, siren or the like~ Preferably, the condition indicia ~ are rather large panels and are prominently located on the housing in a manner to be visible throughoot -an operating area; however, the placement, size and colors for the panels chosen are merel~ a design choice. The operation and actuation of the condition indicia array 6 and 7 as well as the conditions to which they respond will be described in greater detail in con~unction with Figure 3.
The face 5 of the electrical control and alarm cabinet 1 is also provided with a digital display 8 and a pair of chart recorders 9 and 10. The digital takes the form of a flow rate counter providing a digital output which displays the flow rate in liters per hour ~herein the measured flow-rate corresponds to the flow rate of the liquid peroxide ~eing provided at the output of the peroxide feed cabinet 2. The chart recorder 9 -takes the form of a two track analog recorder which maintains a record of both the metered flow and the line or extruder speed, 2S measured in the manner to be described in con~unction with : - 8 -i~7~1~38 Figure 3, so that a history oE the system operation with respect to that set is automatically maintained and displayed. Similarly, the chart recorder 10 is a six track event recorder which indicates graphically the time and condition of any system .
warnings which may have been issued by the system in a manner to be further described in conjunction with Flgure 3.
The face 5 of the electrical control and alarm cab:inet 1 is also provided with an hour meter 11 which is used to record the cumulative operating time of a system incremental pump~
as shown in Figures 2 and 3. Additionally, power On and Off switches 12 and 13 are provided as well as a pair of rate control potentiometers 14 and 15. The power on control switch 13 is a two position, mode control s~witch which automatically returns to a home position identified with the automatic mode of operation when not held in its second position. This second position is .:
: a manual mode or a mode which is independent of the level control : employed for protective purposes within the fluid feed vessel, and will be described in detail in conjunction with Figure 3, In the home or automatic position, th:e power On switch 13 .:-.
causes the system operation to be controlled in response to an ^ ..
error signal which is derived from the difference between the actual flow rate of the s~stem and a referenced condition established by a mode control switch 16, also pro~-ided on the ~ :
face 5 of the electrical control and alarm cabinet. The referenced condition is set by the operation of the mode control switch 16 which employs, in a first or start up position, the ~ :
speed of the extrudier 3 screw and in the second posit~on employs .~::
the product output rate from the continuous vulcanization tube 4 as th.e reference standard so that, in this manner~ the flow rate at which li~uid peroxide is in~ected is made to identically .~ .
correspond to the rate at which processing is occurring to .; ;

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78~

ensure that a precisely metered amollnt of liquid peroxide is injected for the rate at which the polyolefin compound is being processed. The electrical control and alarm cabinet l is also provided with a lock means to prevent access by unauthorized personnel.
The peroxide feed cabinet 2 as shall be seen in greater detail in connection with Figure 3 is. a vent:Llated cabinet in which the liquid peroxide is stored wh.ich contains all necessary ducts and conduits Eor conveying precisely metered liquid peroxide to the output thereof at conduit 17. The output 17~ as shall be described hereinafter, is connected to the extruder i.nput at the base of the hopper employed to suppl~ cross-linkable polyole-fine to the extruder. The fron~ of the peroxide $eed cabinet 2 is provided with a float type glas6 tube 18 which permits th.e visual monitoring of the actual flow in a manner illustrated in ~ : :
greater detail in connection with Figure 3. The construction :
of the peroxide feed cabinet 2 is~such that a highly constrained and controlled environment is provided for both the liquid .. ::.
peroxide storage and feed equipment so that safe conditions ~-are maintained or else system shut down is initiated~ Thus, the peroxide feed cabinet 2 is ventilated and should proper ~.
ventilating action terminate, an abnormal condition is indicated. ;- --.
Similarly, the peroxide fill tank is monitored and should the temperature rise, an abnormal condition is indicated. In addition2 feed vessel is refrigerated and ventilation is insured th.rough .
an under pressure venting system, in a manner ~ell known to those .
of ordinary skill in the art which is implemented th.rough leak-proof tubing. All feed throughs of conduits and electrical cables utilize seal proof gaskets and any electrical equipment contained ..
within the cabinet is either explosion proof or connected to supplies which are inherently safe. Furthermore, the pow-er levels employed are calculated to avoid.arcing and all electrical connections are ~rought to a terminal board within the electrical - 10 -- .:

10~8188 ¦ control and alarm cabinet 1. Catch basins are additionally provided ¦ throughout in case of leaks and leaks are monitored by a sump and a pneumatic level indicator to cause the indication of an abnormal or dangerous condition. The entire peroxide feed cabinet 2 is separate and apart from the electrical control and alarm cabinet 1 and it may be located at a variable distance from the extruder to en~ure safety in ope~ation. All parts within the peroxide feed cabinet which come into contact with metered liquids are strictly non-corrosive and neutral with l respect to the liquid peroxide being employed and hence should take the ~ form of stainless steel, glass,TeflonOpolyethylene or similar types of ~eutra~ non-corrosive tubings. The connecting ducts for the installation are also of stainless steel and heavy metals such as copper, are avoided -throughout. A closedcycle refrigeration system is also provided ¦ herein and a fire detection system may be provided, if desired, throug~
the installatlon of ionization chambers for detection of gases emitted through combustion and upon such detection, sensory means may be activated to initiate alarms, and/or subsequent to a delay cause extinguishing gas to be discharged into the chamber. Furthermore, in t~ e case of an external fire hazard, alternate detectors, located on top of the electrical cabinet for the purposes of monitoring the external environment may also be employed to initiate an alarm and the extinguis~ er~
¦ Thus, as shall be seen in greater detail hereinafter, the peroxide feed cabinet 2 is constructed and monitored so that safe operating conditions are maintained throughout or else system operation is terminated.
~ The extruder 3 may take the conventional form of extruder apparatus having a hopper39inwhich the'compound to be cross-linked such as polyolefin is fed. At thebase OI the hoppeF, the conduit 17 is . ~
.. . . .
I . . .

~onnec~ed to directly ln~ect the liquid cross-linking agent 7 which in the exemplary embodiment has been ~escribed as a liquid peroxide, directly into the input of the extruder. In addition, the extruder, takes the conventional form of a hollow outer core 20 with a centrally disposed and rotating extruder screw 21 caus-ing extrusion to occur in the well known manner. Thus it will be seen that granules of the compound to be cross-linked are initially mixed at the input oE the extruder and thereafter the increase in temperature and pressure induced by the operation of the extruder will cause a highly homogeneous mixture of the liquid peroxide and polyolefin to occur and to be process.ed through to the output thereof. Accordingly, it will be ap-preciated that the initial third of the extruder acts to effec- :
tively cause the mixing of the liquidous cross-linking agent and .
the solidus compound to be cross.-linked and thereafter an increase ~ :
in temperature within the extruder, resulting in temperatures from 100 - 140 C, will cause the resulting mixture to assume ~
a highly homogeneous state. Th.e resulting mixture of compounds: .
rhich occurs from the output of the extruder is introduced into : .
the continuous vulcanization tube 4 wherein the same is disposed about a core and thereafter subjected to elevated temperatures so that actual cross-linking ~ay occur. .. :
More particularly, the continuous vulcanization tube 4 takes the form of a steel tube 22 forming a heating chamber 24 which receives steam or super h.eated water, under pressure. The input portion of the continuous vulcanization tube 4, is provided with a central opening 26 adapted to accept core material about which an insulating layer of cross-linked polyolefin 23 is to be disposed and an annular conduit portion 28 adapted to receive the output of the extruder screw from th.e extruder head 25.
As will be readily appreciated by those of ordinary skill in the ~78~L~8 art, the liquidous output mixture from the extruder is continuously disposed about core mater~al as the same is fed into the central opening of the extruder head 25 so that this material is vulcanized in a continuous manner about the core material being fed in the direction indicated by the arrow A. Thereafter, the core thus coated with the extruded mixture is run through the heated zone of the continuous vulcanization tube so that cross-linking of the mixture occurs in the manner lndicated on a continuous basis so that continuous processing techniques may be employed throughout. ~s indicated in Figure 1, the length of the cross-linking zone is sufficient so that-cross-linking of the homogeneous mixture from the output of the extruder can be completed prior to leaving the continuous vulcanization tube ~and hence, all processing which occurs is carried out on a continous basis, As the exemplary embodiment of the instant invention being disclosed in association with Figure 1 has presumed that polyolefin compounds are supplied to the hopper 19 and liquid peroxide is injected at a precisely metered flow into the conduit 17 for mixing within the extruder and subsequent continuous vulcanizing about a core 27, it may be assumed that the core 27 comprises electrical cable or conductor means as the resulting compound is a highly advantageous insulator.
However, it wlll be appreciated by those of ordinary skill in the art that any liquid material of a volatile nature may be injected at a precisely metered basis from the output of the peroxide feed cabinet 2 and similarly, any compounds which call for organic peroxides for their cross-linking or vulcanization of any other compounds which require highly volatile cross-linking agents may be employed. Typically, compounds which could be introduced into the hopper means for advantageous combination w th organic peroxides for cross- ~

: ~-' 7~

link:ing or vulcanization are as follows:
polyethylene ethylene propylene copolymer (EPM) :
ethylene propylene diene terpolymer (EPDM) chloride polyethylene (CM) chlorosulfone polyethylene (CSM) tolyethylene polyethylene (CSM) vinyl acetate ethylene copolymer (EV~) natural rubber (NR) polyisoprene (IR) butadiene styrene rubber (SBR) polyisobutylene silicone rubber .-acrylonitrile butadiene rubber (~BR~ .
Similarly, while an extrusion and vulcanization techni~ue has been employed in the exemplary embodiment for the output of the .
peroxide feed cabinet 2, any mixing or combining and forming techniques, well known to those of ordinar~ skill in the art~
which may be performed under ambient conditions with either liquid peroxide or highly volatile compounds on a precisely 20 metered basis may be used in combination ~ith the principles -of the instant invention.
Referring now to Figure 2, there is shown a highly .
generalized schematic illustrating in a highly simplified manner~ :
the techni~ues employed by the instant invention for precisely .~:
metering and controlling th.e in~ection of highly volatile .`. cross~linking agent while the maintenance of ambient conditions :~
required for safe operations are rigi.dly controlled. Th.e ~ .
apparatus illustrated in Figure 2 comprises ~he simplified ;-~
schematic for the embodiment of the invention illus:trated in :.
Figure 1 and comprises a storage tank 30, feed vessel 31, .~

incremental feed pump 32, output transducer means 33, safety . - .

' :
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valves 34 and 35, a flow meter 36 and the extruder 37 and with the exception of the extruder 37 each of these elements resides in the main channel of fluid flow. The storage tank 30 may take any conventional form of storage tank capable of holding liquid peroxide or such other highly volatile cross-linking agent as is employed in a given system. In addit~on to the volatile cross-linking agent, other addltlves such as certain antioxidants which are soluble by direct addition to liqllid peroxide or the like may be present within the storage tank 30 so that the cross-linking agent to be in~ected already includes such additives as are des-ired~ The antioxidants which may be added may take the form of:
44~thio-bis(6 terbutyl-meta~cresol), 44'-butylidene-bis (6 tert. -butyl. -meta~ -cresol),

2.6 - di-tert. -butyl. -para-cresol, 2.2' - methylene-bis (6 tert~ butyl. -para-cresol) Thiobiphenol These antioxidants can be completely dissolved in peroxide in sufficient proportions for effective protection of the polymer without altering the efficiency of the peroxide or of the antioxidant.
The s$orage tank 30 is connected through a conduit 38 and a pump 39 to the input of the feed vessel 31~ The feed vessel 31 may be provided with a fill control device, represented by the input annotated N. This fill control device may be initiated either by manual or automat~c control in a manner to be described more in detail in con~unction with Figure 3. How-ever, the actual start and stop actions of the pump 39 are initiated by a float switch within the feed vessel 31 which acts -magnetically on contacts associated with the power input for the pump 39 in a manner also described in greater detail in . - - - ~

!38 connection ~i~h Figur~ 3. Additionally 7 the flo~t action within the feed vessel 31 acts to provide a mini.mum level condition which, acts to initiate indicia advisory that an upcoming product shortage in the feed vessel 31 is about to occur through audible and visual indicia in a manner to be more fully discussed in connection with Figure 3. Switched contacts are also employed to start and stop the automatic fill whlle a maxlmum level sensory condition associated with the float control automatically terminates the automatlc or manual filling of the feed vessel 31 and provides an advisory indicative of this condition through both visual and audible indicia. The feed vessel 31 is connected through a conduit 41 to an incremental Eeed pump 32 which transmits a pulsed stream of peroxide or other cross-linking agent in response to control signals supplied at the input thereto annotated C. The incremental feed pump 32 is actually controlled by the production speed of .;
the product coming out of the continuous vulcanization tube or alternatîvely by the speed of the screw ~ithin the extruder 37 in a manner to be covered in greater detail in connection with ~ -. .
Figure 3. Here, it is sufficient to recognize that a control is provided to compare the actual flow rate of the system wh.ich is injecting liquid peroxide or other cross-linking agents and .:
the speed of the extruder screw or the output of the continuous vulcanization tube and the output of this control signal is . :
applied to the incremental feed pump 32 so that the rate of flow is maintained at the precisely metered rate required by the -~`:
processing operation which is then occurring. The incremental :. ~:

',~.' :

- 16 - ~ :

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feed pump may be bypassed by a pressure limiting valve ~3 connected between the input 41 and output 42 of the incremental Feed pump. The pressure limiting valve 43 acts in the well known manner to isolate the input and output to the incremental feed pump 32 whenever the pressure at the output thereof remains below a specified level while breaking down to cause the output : to effectively be connected to the -input whenever the pressure at the output of the incremental ~eed pump 32 exceeds such predetermined level. The pressure limiting valve 43 may als.o be employed as an alarm should the pressure dif~erential which it is designed to measure exceed a predetermined level or alternately, a direct reading gauge may be employed to provide this Eunction as well as a direct display function ~or the operator. The output of the incremental feed pump which transmits the peroxide as a pulsed stream is further filtered and regulated by a group of hydro-pneumatic dampers 44 which act in the well known manner to smooth and order the stream of peroxide -.
pumped from the output of the încremental feed pump 32.
The output of the incremental feed pump 32 thu~
20 smoothed îs applied through. conduit 42 to the input of an output transducer 33 which acts, i.n essence, to measure the rate of flow and produce an output signal V representing th.e .~
flow rate, which is obtained, in a manner to be more fully .
discussed in connection with Figure 3 This flow rate .. ;
signal, as obtained from the output of the output transducer 33, .~ -~
is employed in conjunction with th.e rate signal developed from the speed of the extruder screw or the mater~al processed at ~:
the output o~ the continuous vulcanizati.on tube 4 to develop~-the error~signal used to control the :

- : . .

~ 88 increment~l feed pump 32 and hence the flow rate with which peroxide is ¦ run through the system. After the rate of flow is measured by the output transducer 33, the peroxide being pumped is supplied through electrically actuated safety valves 34 and 35 and a flow meter 36 to the 5, input of the extruder 37 through conduits 45 - 48. The pair of electrical safety valves 34 and 35 are disposed just at the output OI the output transducer 33 and at the input to the extruder 37 so that She same may be simultaneously closed off should an emergency or abnormal condition arise to cut off the feeding of peroxide both within the system andat the I output thereof so that the flow is immediately terminated at several locations. The flow meter 36 is a glass tube and ball flow meter of the well known variety and corresponds to the flow meter 18 illustrated in Figure 1 which permits the operator to visually monitor the flow of liquid peroxide within the peroxide feed cabinet 2. The conduit 48, it should be noted essentially corresponds to conduit 17 in Figure 1 and the input thereto at the extruder 37 corresponds to the input position at the -base portion of the hopper. The pair of electrical safety valves 34 and 35 will close either when the incremental pump 32 stops or should the electrical supply be interrupted so that the supply of liquid pera~ ide to the injection point at the extruder 37 is immediately cut off.
Polyolefin compound or the like is supplied from the hopper49 ;, ~ `~
which would correspond to the hopper 19 illustrated in Figure 1 and through a conduit 50 to the input portion of the extruder 37. Thus, the ~olyolefin compound will enter into the input portion of the extruder 37 ~5 at the same time as the crosslinking agent is injected through conduit 48 -under ambient temperature and pressure conditions, whereupon the ., . ' ' ' .
': '`'-. , ~
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extrusion process and the continuous vulcanization and cross-linking processes described in association with Figure 1 may take place without any initial preparation of compounds to be sub-jected to the process and safe operating conditions are maintained throughout because the amount of cross-linking agent is precisely metered to correspond to that required by the rate of processing.
~11 internal parts of the apparatus ~hich come in contact with liquid peroxide or other volatile cross-linking agents which may be employed are made Erom stainless steel, Elorosilasomer, polytetrafluoroethylene or any other material not sensitive to peroxide or other cross-linking agent action. Furthermore, since these agents tend to be flammable, a plurality of safety devices are added, as shall be described in more detail in connection with Figùre 3, to ensure the safe operation of the cross-linking agent injection system. For instance, the storage tank 30 and the feed vessel 31 are refrigerated while an enclosure 51, as indicated by the dashed block, is provided in the manner shown to maintain the environment of the system w-ithîn desired parameters. The enclosure 51 is fabricated so as to be leak proof to the cross-linking agents conveyed should leaks or spills develop within the system and it is sub~ected to a negative pressure by an extractor 52 whose discharge is evacuated through leak proof tubing and sealing arrangements. The extractor 52 may take the form of a conventional under pressure extractor which is a fan type device wherein venting to an external environment is accompli:hed through a sealing arrangement.
Additionally, sensory devices responsive to the ventilation control of the extractor 52 and the temperature within the en-- closure 51 are provided to initiate alarm conditions should either the ventilation fail or the temperature rise~ Further-more, catch basins (not shown) are provided throughout the :

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~C378~

enclosure beneath peroxide handling equipment s:hould leaks.
develop and the catch basins may be provided with fluid level detectors to indicate the presence of a leak and initiate an alarm condition. In addition, all electrical connections are made to a terminal board located outside of the enclosure 51 so as to avoid the possibility of spark ignition.
Referring now to Figures 3A and 3B which connect from left to right, referred to generally as Figure 3, there is shown in great detail a schematic diagranl illustrating the details oE the volatile cross-lInking agent feed or supply system an-l the electrical control and ala~m equipment for the e.xemplary continuous extrusion embodiment of the invention illu6trated in Figure 1. As should now be apparent to those of ordinary skill in the art, although the exemplary embodiment herein discussed includes an extruder and continuous vulcanization tube . .-for forming a resultant mix of volatile cross-linking agent and polyethylene about a core to form a resultant product, the .~
volatile cross-linking agent supply system according to one --aspect of the instant invention may be employed an~ time it is necessary or desirable to feed precisely metered quantities of a liquid to a given location and the nature of the liquid ~:`
involved requires extremely rigorous h.andling requirements. :; ;.
Furthermore, it will be apparent that although a multitude of safety features are included within th.e instant invention to .~ .
insure the safe operation of the volatile cros:s-linking supply ~
system, selected safety features may be added or deleted to . .:-meet the requirements of a specific application. As a generalized .
block diagram of the exemplary embodiment of the present invention ~ -was set forth in conjunction with Figure 2, the description of ~
~igure 3 will proceed to set forth the details of the schematic diagram illustrated therein as an overview has already been .

.
.... . ..

: .

provided in conjunction with Figure 2~ In the description of Figure 3, initial focus is directed to portions of the supply system associated ~ith the flow of volat~le cross-linking agent while control, safe~y, and metering equipment associated ~herewith is either described in association with elements which are controlled thereby or in separate s~ectiorls of this descr:Lption devoted to such control circuitry.
In essence, the schematic diagram illustrating the details of the volatile cross-l~nking agent ~eed or supply system and the electrical control and alarm equipment for the exemplary continuous extrusion embodiment thereof, as illustrated in Figure 3, comprises a storage facilIty for liquid cross~-linking ~
agent 61, a pumping and metering compartment indicated by the ~-dashed block 62, material and processing equipment indicated by the dashed block o3~ display and alarm indicia 64 and 65 ;~
and various control, and sensing equipment to be described hereinafter. The storage facility for liquid cross-linking agent is disposed within a separate chamber of the peroxide feed cabinet 2 illustrated in Figure 1 and is employed to store a small quantity, 100 liters maximum, of cross-linking agent in liquid form. The liquid cross-linking agents selected may t~pically include:
di-t butyl peroxide (DTBP) 2,5-dimethyl-2,5-di(t-butylperoxy) hexane 2,5-dimethy1-2,5-di(t-butylperoxy)-3-hexyne t-butyl cumyl peroxide 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane 2,2-di(t-butylperoxy)propane 2,2-di(t-butylperoxy)butane or cumyl hydroperoxide, The storage of the cross-linking agent within the storage facility 61 is compartmented in flasks as indicated by flasks or vessels 66-69 with liquid .. ~- ,: : : -1~78~

cross-linking ~gent being pumped from the storage facility 61 through a conduit 70. For the conduit 70 shown, an operator would be required to reposition the conduit within a full flask each time a need for a new supply of cross-linking agent was indicated by the minimum level indicia, to be described herein-after; however, as will be appreciated by those of ordinary skill in the art, branching and valving of a plt1rality of :
conduits for the flasks could be provided so tl~at a new supply as well as the substitlltion of full flasks Eor empty Elasks could be achieved by merely turning a val.ve and once the flask .
was isolated from the system, an empty flask could then be ~ .
replaced. The storage facility for liquid cross-linking agent 61 is an enclosed chamber as indIcated and is refrigerated by a ;i :
closed circuit refrigeration or "lost" water refrigeration system indicated by the dashed block 71. The lost water or closed circuit refrigeration system indicated by the dashed : block 71 includes a motor 72 which drives a pump 73 which in turn drives cooling liquid, maintained at a temperature wh.ich is below 16C through the conduits 74-76 and the heat exchanging .::~
portion 77 to cool the storage facility for liquid cross-linking - :.
agent 61 in the well known manner. The closed circuit refriger- ::
ation or lost water refrigeration system indicated by the dashed block 71 may take any conventional form of -this well known class of devices or alternativelyS any suitable reErigeration .
system may be employed in its place.
Additionally, for the purposes of protecting the .~ .
system against an outbreak of fire, a conventional ionization chamber 78 of conventional construction is disposed within the storage facility 61 for the purpose of detecting gases .:
emitted by combustion and to transmit information indicative ~:
of this condition to fire indicating means indicated by the - 22 - :

1~78~L8~

dashed block 7~ ~hrough conductor 80. The ~ire indicating means indicated by the dashed block 79 includes an amplifier 81, an instantaneous operating relay 82 and a delay relay 83.
Accordingly, as will be appreciated by those of ordinary skill in the art, whenever a combustion gas- is detected by the ionization chamber 7~, this signal is conveyed thro-lgh conductor 80 and amplified by the amplifier 81 in ~he well known manner ;:
to cause a triggering of the instantaneous relay 82 :eollowed by delayed actuation of the relay 83. When ~he instantaneous relay 82 is triggered in the ~oregoi.ng manner, QS shall be further described above, system ventilation is terminated and a red alarm signal coupled with the acutation of a horn is initiated.
Thereafter, when the delayed relay 83 is triggered, the closing of the contacts associated therewith will cause flask 84, to be opened whereupon fire extinguishing gases as contained therein are conveyed through conduit 85 to extinguish any ~ire which may be in the process of occurring wîth.in the storage facility for liquid cross-linking agent 61. Accordingly, it will be appreciated that the storage ~acility for liquid cross-linking agent 61 comprises an essentially sealed storage facility which is refrigerated to maintain the volatile cross-linking agent in a cooled condition and is provided with an independent fire detection and extinguish.ing system so as not only to be ~ -isolated from its environment but additionally to be self-protected. Alternatively, solid peroxide or other cross~linking agents in-solidus form may be employed within the storage facility for liquid cross-linking agent 61; ho~ever, under these conditions J it ~ould be necessary to provide for the controlled heating of the container and ducting so that the environment ~ .
established within the chamber is- set to maintain the peroxide in its liquid state into which it w-ould be first rendered through .: . . . . ,, . ~ .............................. . - - :
-,'' -, :
a melting process.
The pumping and metering compartment indicated by the dashed block 62 comprises a fill pump 88, a feed vessel 89, metering pump 90, hydropneumatic dampers 91 and q2, a pressure limiting valve 93, a pressure gauge 94, a ~low transducer ~5, electric safety valves 96 and 97, a ~low meter 98, negative pressure venting means 99 and catch basin means 100. The fill pump 88 may comprise a conventional pump which is employed to draw liquid cross~linking agen~ Erom the sto-rage eacility 61 through conduit 70 to the feed vessel 89 through the conduit 101, The fill pump 88 is driven as indicated by conventional motor means 102 which e.ither may be located within the pumping and metering compartment 62 if the same is o~ an explosion proof design or may be disposed without the pumping and metering compartment and merely connected through a drive sh~ft or the like to the fill pump loaded therein. The motor means 102 which may comprise either conventional AC or DC motor means is energized through a set of contacts 103 ~o a conventional power supply (not shown). Both the set of contacts 103 and the power supply would be located outside of the pumping and metering compartment 62 and preferably w-ithin the electrical control and alarm cabinet 1 as shown in Figure 1. Accordingly, as will be appreciated by those of ordinary skill in the art, the motor means 102 is energized to cause cross-linking agent to be pumped through conduits 70 and 101 into the ~eed vessel 89 whenever the contact set 103 is in a closed cond;t~on.
The contact set 103 which acts to cause the fill pump 88 to be energized ln the foregoing manner is controlled by the condition of the pump relay 104 which is conventional and acts to close contact set 103 whenever potential is applied thereacross from the potential supply 105. The potential supply 105 may comprise any conventional AC source of potential ~ 24 - :
:
''; '.: - ' :- : - . - . , . : - . . . . : . :,: . - . - :

~78~

or alternatively a DC source may be employed if this farm of relay is preferred. The potential supply 105 is directly connected to one side of the pump relay 104 through conductor 106 and to the other side thereof through conductor 107 and the combination of switches 108 and 109, 108, 110 and 111 or 108, llO and 112 whichever group of switches is in a closed condition to establish the serial path to the pump relay 10~.
Of course, should no serial path be established tc connect relay 10~ to conductor 107, the relay will be in a de-energized state whereupon switch contacts 103 w~ill be in an opened condition and the fill pump 88 will be inoperat~ve. The switches 108, 111 and 112 are controlled as a function of the level in th.e feed vessel 89 in a manner to be described belo~ and hence it i5 here sufficient to appreci.ate that switch 108 is opened to indicate a safe maximum level condition and terminates the operation of the fill pump 88 while conversely, switch 112 is acutated to indicate a mînimum level within the feed ves.sel 89 and hence indicates a condition associated with an eminent lack of cross-linking agent in the flask presently being employed within the storage facility for liquid cross-linking agent 61.
The opening of contacts 112 w-ill not, however, stop the action of the fill pump 88 as no danger results when the s~ystem runs out of fluid and warning devices which are provided are sufficient to apprise an operator to immediateIy correct the condition~ :
In similar manner, the contacts lll are in a closed condition when a normal level resides within feed vessel 89 and an opening of this set of contacts will not result in pump termination so long as th.e minimum level associated w;th contact set 112 has not also been exceeded. This means, as will be readily appreciated by those of ordinary skill in the art that .~.
an overlap may be established b~tween th.e normal level indicated :

- 25 ~

~C~7~

by contacts 111 and the safe mini~um level indica~ed by contact set 112 50 that an operator is warned to input more cross-linking agent into the storage facility for liquid cross-linking agent prior to actual termination of the operation o~ the fill pump 88.
The switches 109 and 110 comprise a ganged pair of switches which are biased to the condition shown. The closed condition of switch 110 is definitive of the automatic mode oE
operation of the system which is :Lmplemented whenever an operator depresses the Power On button at ~he electrlcal cabinet.
During the automatic mode oE operation it will be appreciated -that the minimum and normal level controls associated with switches 111 and 112 are operative. However, for cases where -the system must be serviced, a push button associated with contacts 109 is provided w-ithin the electrical control and alarm cabinet 1 which will energize rela~ 104 and cause the pump to be driven regardless of the condition of switches 111 and 112 so long as the push button is held depressed to overcome the normal biased condition oP the ganged set of contacts 109 and 110. It should however be noticed that the maximum level condition associated with contacts 108 is always operative as it would be undesirable to let even a repairman initiate a set of conditions where the feed vessel 89 could overflow.
The feed vessel 89 is adapted to receive pumped cross-linking agent through conduit 101 in the manner indicated and to sup~ly cross-linking agent to the metering pump 90 through conduit 113, the filter 114 and the conduit 115. Within the feed vessel 89 resides a level float 116 which acts in a conventional manner to magnetically actuate respective ones of the switch contacts 108, 111 and 112 and thus to control the action of the fill pump 88 in the manner described above -~
and hence, control the level within the feed vessel ~9. It should - " . . .

- . . . ... . ,....... .~ , , ,, .- , . . .. , : .

1~78~

be noted that ~henever either the maximum level condition associated with switch 108 or the minimum level condition associated ~ith swîtch 112 are actuated, appropriate ones of the condition indicia 6 and 7 shown in Figure 1 are initiated.
~Iore particularly, as shown by the dashed lines 117 - 120, appropriate condition indicia as depicted by the condition indicia arrays 121 and 122 illustratecl in Figures 3~ and 3B
are energized. Thus, whenever a maximum level condition is indicated magnetically by the level float 116 and switch 108 is opened, the contact set 123 is closed to illuminate the maximum level alphameric panel indicia in the condition array 121 and as is illustrated by the conductor 125, the orange warning light in condition indicia array 122 is energized.
Similarly, whenever a minimum level condition results in the opening of contacts 112, a set of contacts 124 are also closed to cause the minimum level condition indicia in condition indicia array 121 to be illuminated and as is also indicated by the conductor 126 to cause the red warning condition indicia in array 122 to be illuminated~ Furthermore, as indicated by the conductors 127 and 128, whenever either the red ~r orange condition indicia are illuminated, a horn 129 is also sounded to additionally solicit an operator~s attention. The feed vessel 89 is additionally refrigerated in the same manner as the storage facility for liquid cross-linking agent 61 by the closed circuit refrigeration or lost water refrigeration system 71 through the winding of the conduits 74 and 75 therearound in a serpentine fashion. Alternatively, if liquified peroxide developed from solid peroxide w-a~ being supplied to the feed vessel the feed vessel could be heated in the same manner, described above, for the storage facility for liquid cross-linking agent 61. Fluid may be drawn from the feed vessel o9 ~078~8 by the metering pump 90 through conduits 113 and 115 and the Lilter 114. ;:
The metering pump 90 may take the conventional form of an incremental pump which is driven by the motor 130 disposed outside the pumping and metering compartment 62. The speed with which the motor drives the incremental pump 90 will be dicussed in greater detail below, however, at thls ~uncture in the specification, it is sufficient to appreciate that the speed oE the metering pump is closely controlled by an error signal so that precisely the right amount of cross-linking agent ls injected into the base of the hopper for the rate in which processing is occurring wherein both 10w rate and processing rate can be measured in several fashions. The output of the metering pump 90 in the form of a pulsed flow whose rate is ~ a function of the speed with which the motor 13Q is being ~:.
driven is supplied to the conduit 131 for application to flow transducer 9S.
The pulsed flow applied to the conduit by the ~ incremental metering pump 90 i5 smoothed ~y a series of h.ydro-~0 pneumatic dampers 91 and 92 which may be conventional and act in the w-ell known manner to regulate the flow due to the . ~ .
. pressure regulating effect of the air or other media therein ; on the fluid levels ~hich are also present therein. In addition, the metering pump is protected by a pressure limiting . .
valve 93 which may also be conventional and acts in the well known manner to connect the output of the pump to its input t~
thus release the pressure in the exit line wheneverthe pressure in the line exceeds the pres:sure to wh.ich. th:e s-ame is: set th.r~ugh. .:~a spring or other biasing means. The p~es:sure in th.e exit line 131 is also directly measured b~ a pressure gauge 94 to furthe.r apprise the operator of the functions whi~ch are occurring w~ith.in - 28 ~
": ' ' , . , , ~ . . . , . .: . .. . .

1~71~8 the syqtem.
The regulated output oE ~he metering pump 90 is thus applied to the input of the .~low transducer 95 through conduits 131 and 132. The flow transducer 95 may take the form of a conventional differential flow meter or alternatively, a magnetic thermic or ultrasonic flo~ meter could be employed. In the case of a differential flow~ me-ter, th.e relationship bet~een the pressure being proportional to th.e square of ~he flow rate is employed to generate a s.~ignal on conductor 133 whi.ch is thua proportional to the square of the flow rate.
The signal on conductor 133 as developed as. a function of the square of the flow rate through. the differential pressure techniques employed b~ the flo~ transducer 95 is uti.llzed QS. a preferred method of determining the flow rate within the system so that the same may be displayed and also used where desired to develop an error s.ignal for controlling the speed of th.e metering pump motor 130. More particularly, the signal re- -.. presenting the square of the flow rate i5 applied to a linear :~
amplifier 134 which may be conventional and is employed to shape : ....
the signal on conductor 133 in the well known manner~ The output of th.e linear amplifier 134 is then applied through conductor 135 : -to the input of a square root extractor 136 which may take the conventional form of a differentiator or the like. Th.e output of the square root extractor 136 wh:ich. is a signal ~hich is now-directly proportional to the flow- rate of fluid being applied .. :~
to the flow transducer 95 i~ applied through. conducto~ 137 to . :;~
the input o~ a linear amplifier 133 for additional sh.aping and ampl~fication in the conventioDal manner. The resulting signal .-obtained at the output of amplifier 130 is: applied to conductor .:.
139 tc potentiometer 140, which h.ere acts as a sensitivity ad- -justment, and is thereafter appl~ed th.rough conductors 141 and .
142 to the inputs of a digital display 145 and one input of an . . .. - :
- 29 - `

.

. , .. ~ - - . .- , ~.~7~

an~log recorder 146 so that the flow rate thus obt~ined may be directly displayed to the operator in terms o:~ ]iters per hour and recorded for reference purposes. The digital display 145 corresponds to dîgital display 8 in Figure 1 while the analog recorder 14~ corresponds to the two track analog recorder 9 as also shown in Figure 1.
The flow rate signal obtainecl from the output o:~
potentiometer 140 on conductor 141 is a negative signal represent-in~ the Plow rate and is employed, after suitable manlpulation, to develop an error signal from summing point 150, under conditions where actual flow rate is belng utilized to develop the error signal. Once the error signal is developed at summing point 150, it is applied to a conventional di:~ferential amplifier 151 and a thyristor bridge 152, which also may be conventional, so that a drive signal proport~onal to the error s~gnal is .
applied through conductor 153 to control the speed of the metering pump motor 130 and hence the flow rate through the system as -determined by the speed of the incremental metering pump 90. . `.
More particularly, when flow rate is to be employed in the development of an error signal, which is the automatic mode set :' a-t the console to be distinguished from the manual mode, the -s~itch 154 is- in a closed condition while the switch 155 is in ~
an opened condition, i.e,, opposite to that illustrated in Figures 3A and 3B. Under these conditions, the negative flow rate signal ~ :
developed as a negative level from the output of potentiometer 140 on conductor 141 is applied through conductors 142 and 156, a ~ :
, - resistor 157, conductors 158 and 159, the closed switch 154 and ~ :
....
.: ..
the conductor 160 directly to the summing point 150. In addition, : -the negative flow rate signal on conductor 141 is applied through .~

a resIstor 161 to a summing point 162 where it is combined with a ;~.
positive signal representing, as shall be seen below, either the ~- .
~ ~ 30-, - . ~. ~. .- ; ~

rate at which completed material is being processed or the speed of the extruder screw so that a measure of the processing rate is effectively applied through conductor 163 to the summing point 162. Accordingly, the output of the summing point 162 on conductor 164 represents a system error signal which is then applied to the integrator formed ~y the capacitor 165 and the operational amplifier 166. The error signal is thus integrated and inverted in the well known manner ancl thereafter applied through ' conductor 167 tn the input of the inverting amplifier 16B. The correc-tion signal thus obtained at the output of the inverting amplifier 168 is applied to conductor 169 where it is algehraically summed with the, negative flow rate signal on conductor 158 whereupon the resulting signal is applied through conductors 159, the closed switch 154 and conductor 16û to the summing point 150 where an additional component signal is added to the modified flow rate signal applied to conductor 160 under this set of conditions. More particularly, a tachometer generator 17û
is connected in the convention manner to measure the speed of the motor 130 and develops a negative signal proportional to the speed thereof. This signal is then applied -through a voltage divider ~ormed by resistors 171 and 172 to the conductor 173. As the switch 155 is in an opened condition due to the automatic mode of operation set by the operator wherein actual flow rate measured by the flow transducer 95 is employed in developing an error signal, only the AC portion of this signal is applied through capacitor 174 to the summing point 150 -as a damping signal for the resulting signal applied on conductor 160.
Thus it will be seen that when actual flow rate is being employed in developing an error signal at the summing point 150, the actual flow rate is measured by the flow rate transducer 95 and displayed at the ~ ;
digital display 145 whereupon this signal through conductor 156, resistor 157 and conductor 158 is summed algebraically with the integral of an error signal developed at summing point 162 and added to a damping signal developed from the output of the tachometer generator 170 whereupon the resulting sum is applied to the summing point 150.

~hen the automatic mode is established by -the operator, the switch 154 is placed in a closed condition while the switch 155 is opened ~8~
as aforeslid. ~dclitionally, the establishment of this mode places the s~itch 176 in the condition illustrated in Figures 3A and 3B so as to connect a second input of the summing point 150 to conductor 177 through a resistor 178. The conductor 177 is connected to a switch 179 which may be set at the console by the operator and is determinative as to whether the rate at which finished material is processed a-t the output of the continuous vulcanization tube or the speed of the extruder scrcw i5 to be employed as a measure oF the rate at which the processing of rnaterial in the hopper is being processed. More particularly, iF the material processing equipment within the dashecl block 63 is considered, it will be seen that the items illustrated within this block include the extruder screw 180 and material pulling equipment 181 which, in the case of the cable making application discussed in association with Figure 1, wnuld cornprise pulling equipment suitable for withdrawing finished cable from the end of the continuous vulcanization chamber at -the rate at which the same was being made. Thus, in the case of the extruder screw 180, the speed with which the same would turn would normally be expected to measure the rate in which material was being processed From the hopper -while in the case of the material pulling means 181, the rate at which actual cable was being made, in the exemplary embodiment, would be determined by the rotation of the driven wheels thereof indicated by the idler wheels 182 and 183. In actuality, the rate at which the idler wheels 182 and 183 are driven by the pulling of finished cable would constitute the better measure since extruders are notorious for clogging or becoming dirty and hence their rate of rotation will not represent a constant measure as to the amount of material being processed from the hopper without periodic readjustment. However, there are certain circumstances in ~ .

18~
which this type of measure is desireable such as for initiating the operation and the like.

In each case, a tachometer generator 184 and 185 is employed to measure the speed of the extruder screw or the idlerwheels 182 and 183 respectively and the positive DC voltage developed thereby is applied through the voltage dividers formecl by the resistors 185 and 186 or 187 and 188 to the inputs of potentiometers 189 and 190. Tlle inputs to the potentiometers 189 and 190 are applied through conductors 191 and 1~2 to the inpu-ts of the switch 17~. Thus it will be seen that depending upon the setting of the switch 179, the voltage level applied through conductor 177, the switch 176 and the resistor 178 to the sum- ;~
ming point 150 will be a measure of either the ra-te a-t which completed cable is being pulled from the continuous vulcanization chamber or the :
rate at which the extruder is turning which is an indirect measure of the material being drawn from the hopper. When this positive signal -is algebraically summed with the negative going flow rate signal applied to the summing point 150 it will be seen that the output of the ' summing point 150 which is applied to the amplifier 151 effectively is an error signal representing the difference between the flow rate and the rate at which processing is occurring measured in one of two selected manners. Thus this signal, when applied to the thyristor bridge 152 will drive the motor for the metering pump 90 at a rate to reduce the error signal to zero and hence cause the rate of fluid flow as governed by the incremental metering pump to correspond to that at which volatile cross-linking agent is being employed for processing. It will be appreciated that when switch 176 is in the condi-tion indicated, the lower input to the differential amplifier 151 is zero and hence the summing point 150 in actuality develops the error signal employed. The ~ --33- ~ ~

.' '~
`'-''~:

8~

processing rate applied to the input to switch 179 is also applied through conductor 193 and resistor 19~ to the conductor 163 and hence this rate information is applied to summing point 162 in the manner aforesaid. It should additionally be noted that switch 195 is ganged to switch 179 ~nd hence wil~ receive ~he output of the voltage divider 185' and 186 or 187 and 188 through potentiometers 196 or 197. These potentiometers are set in substantially the same manner as potent:lometers 189 and 190 so that the resulting signal applied to ~he switch 195 and conductor 198 may also be recorded at the two channel analog recording device 146 so that actual flow rate information is recorded with the rate of material processing measured in the manner elected by the operator. The flow rate signal on conductor 144 and the processing rate information on conductor 193 are additionally applied to conductors 199 and 200, respectively.
The signals on conductors 199 and 200, representing the actual flow rate as measured by the flow transducer 95 and the preset flow rate, established by potentiometers 189 and 190, measured as a function of the processing speed, as elected by the operator through ganged switch 179 are applied through conductors 201-206 to individual ones of threshold comparators 207-209~ ~The threshold comparators 207-209 may take the conventional form of deadband amplifiers which each act to compare on a continuous basis, the magnitude oE the error signal as measured between the actual flow rate within the system as established by the signal on con-ductor 199 and the rate at which material is being processed as present on conductor 200. The settings of each of the threshold comparators 207-209 differ and are associated with specific conditions which must be detected for safety indicia and/or auto-matic shut down to occur. More particularly, the threshold am~plifier 207 is associated with a maximum flow condition which is measured by stepping the threshold comparator 207 to a level which is calculated to be 10o above a norrnal flow condition. Therefore, as will be appreciated by those of ordinary skill in the art, whenever the difference in the signals supplied to conductors 201 and 204 is less than a value which is 10~o above normal flow no output is produced by the threshold comparator 207. ~lowever, when the diFFerence hetween these input signals exceed the 10o of normal flow value cstablished, an output level is supplied on concluctor 210 which thus triggers the maximum Flow relay 211. When the maximum Flow relay 211 is triggered, the contact set therein is closed 90 that an energizing level is applied through conductor 212 -to cause the maximum flow indicia within the alphameric indicia array 121 to be energized and in addition thereto, as indicated by the conductor 213, the orange warning indicia is energized in an intermittent or flashing manner and the horn 129, as indicated by conductors 127 and 128 is also enabled. Thus, whenever a maximum flow condition is measured, the maximum flow relay 211 is triggered to initiate a flashing orange alarm and the horn 129 while the appropriate panel within the alphameric display 121 to define the nature of the condition measured is illuminated.

In a similar manner, the threshold comparator 208 is set to measure dangerous flow conditions which are defined as those which exceed a normal flow condition by 50O. Accordingly, the level of -the threshold comparator 208 is set to this magnitude and whenever this condition is detected, an output signal is applied to conductor 214 to trigger the dangerous Flow relay 215. Whenever the contacts within the ~ ~ .

" ~

'.

'``'` ' ^11`'' l ~
l ~78~8~

dangerous flow relay 215 close, as indicated by the conductors 216 and ~17, tne dangerous flow alphameric indics within the indicia array 121 is illuminated and additionally~ the red in(licia within the array 122 is I illuminated on an intermittent or flashlng basis together with the horn ¦ 1~9. Thus, the closure of relay 215 which indicates the presence of a ¦ dangerous flow condition, initiates the sounding of an alarm in terms of ¦ a red flashing light and horn while the appropriate one of the alpha-I meric indicia in array 121 to define this condition is illuminated. In ¦ addition, a second set of contacts 218 which are associated with the .
dangerous flow condition relay 215 are opened to terminate the operatia .
of the metering pump through the control logic associated with the bloc 219 which is subsequently described. Here, however, it is sufficient to appreciate that the control logic within block 219 enabLes the metering pump 90 to be driven in the manner described above so long as the .
- contact set 220 associated therewith is in a closed condition; however, whenever the contact set 220 r~sides in an opened condition, the driving ¦ current for the metering pump motor 130 will not be provided thereto.
Thus, whenever a dangerous flow condition is detected, the metering pump 90 is stopped and an alarm in the form of a red flashing light and a horn is initiated together with an illumination of the appropriate I indicia panel within the alphameric indicia display 121. It should also :
¦ be noted that the contact set 218 associated with relay 215 or the operation of the purnp control logic associated with block 219 may be I timed so that upon detection of a dangerous flow condition, the pump is initially stopped for a short interval, such as five ~5) seconds, and then . ~ . .
is restarted to ascertain if the condition persists; however, should the -. -36 . . . . "~

-.- . . ': ~ ' ~7151~
condition persist~ shut down in a Final manner may then be initiate~l.

The threshold comparator 209, as indicated, is associated with a minimum flow condition and hence, this threshold comparator is preset to establish an output signal on conductor 221 when the di~f~erential measured between the input signals on conductors 2n6 ancl 203 drops below the level corresponding to lOno below normal flow.
When this occul:s, an output signal is provided on conductor 221 to energize the minimum flow relay 222 and hence, signal a minimum flow condition. When the minimum flow relay 222 is triggered, as indicated 10 by conductors 223, and 22~, the minimum Flow display indicia within the alphameric display 121 is illuminated together with the illumination of the flashing red panel and the horn 29. Although not shown in Figures 3A and 3B, the minimum flow relay 222 may have a second se-t of contacts associated therewith to stop the action of the metering pump 90 through a disposition of such second set of contacts in much the same manner as the contacts set 218. Alternatively, a timing - arrangement could also be employed with this second set of contacts to cause a stopping of the pump after a short interval such as five (5) seconds, if this condition should persist or alternatively, the timing 20 could be achieved by the pump variation control logic indicated by the - block 219. Thus, it will be seen that whenever a dangerous flow condition is detected, the metering pump 90 is stopped and an alarm condition is indicated by a flashing red light, the sounding of a horn and the illumination of an alphameric display indicia indicating the condition. Similarly, should a maximum flow condition be detected, a flashing orange light is initiated together with a horn and a display indicia indicating the condition while for minimum flow detection, an ..

. ~ f~3~1L88 ,alarrtl in the lorm of a flashing red light and horn together with an ¦appropriate display panel is issued and the action of the metering pump may be stopped.
Upon a setting of the manual mode control switch by an operato ~, the switch cont~cts 176 are changed in position to cvnnect with the input to potentiometer 225 through conductor 226 Additionally, as was stated above, the switch 154 is opened while the switch contacts 155 are closed so as to reside in the condition illustrated in Figure 3 so that manual operation of the pump may be initiated for the purposes of testing or calibration. Additionally, as shall be seen below, switch contacts 227 associated with the relay 228 and the metering pump control logic 219 are closed to effectively by-pass the dangerous flow and other sa~ety feature interlocks so that relay 228 is maintaine-d in an energized condition to thereby retain the contacts 22û of the metering pump control logic closed so t~at the same can be operative. Although the mode control switch associated with manual nd automatic operation has been stated as present on the face of the electrical control cabinet illustrated in Figure l, the same may be modified so that manual operation OI the pump for testing and calibrating purposes rnay only be inLtiated by an opening of the cabinet and the depression of this switch which would then reside therein to ; -insure that only authorized personnel can implement the manual operation of the metering pump 90 for testing or calibration purposes.
In the manual mode of operation, associated with the switching of contacts 178 to the input~ potentiometer 225 and conductor 226, the metering pump rnotor 130 is essentially driven from a DC level and feedback . ' - ' ' . ."' '' "
. , . ' . ' "" :' . . '.' 0781~8 rep~csel~till" the spc.~ of ihe motor per se is employed thrc~ugh feedbac¦
techniques to form an error signal from summing point 150. More particularly, when switch 176 is placed in contact with the conductor 226, the 15 volt supply of voltage to the potentiometer 225 is stepped down and applied through conductor 226, the switch 176, and the resistor 178 to the summing point 150. Similarly, the negative signal developed by the tachometer 170 as a function of the speed of the metering pump motor 130 is stepped down through the voltage divider formed by the resistors 171 and 172 and applied through conductor 173, the resistor 175, the switch 155 which is now in a closed condition and ¦ the conductor 160 to a second Input to the summing point 150. The ¦ difference between the positLve level from the output of resistor 178 ¦ and the negative level on conductor 160,as thus obtained,is applied from I the summing point 150 to the differential amplifier 151 whereupon the -15 difference signal is applied to the thyristor bridge 15Z and a ¦
driving signal for the pump motor 130 is developed therefrom and I applied thereto through conductor 153. In this manner, the metering ¦ pump motor 130 may be driven for calibraticn or testing purposes under ¦ operator control.
¦ The final element associated with the driving of the metering pump motor 130 is associated with the metering pump variation control ¦ -¦ logic indicated by the block 219. This logic, when in an op~ative condition, will close a set of contacts, not shown, to cornplete the circ~it to the input ~e the metering pump drive motor which resides between ~ the differential amplifier means 151 and the motor 13~ wherein any location therein is suitable. Alternat;vely, the control of the metering _39_ pump logic indicated by the block 219 may be associated with a triggering function of the -thyristor bridge 152. In any event, the pump variation control logic associated with the block 219 may serve to moni-tor any functions of the me-tering pump motor 130 or the me-tering pump 90 which are deemed desireable and in addition thereto an external set of contacts 220 associated with the metering pump variation control 219 are employed to terminate the action of the metering pump any time an abnormal or dangerous condition occurs within the system. More part:icularly, the contacts for the metering pump con-trol logic indicated 10 by the blocks 219 are controlled by a relay 228 which additionally controls the set of contacts indicated as 229 and 230. Thus, when the me-tering pump relay 228 is in an energized condition, the contacts 220, 229 and 230 are in a closed condition whereupon the pump variation control logic indicated by the rectangle 219 may control the operation of the metering pump motor as aforesaid. Additionally, with contacts 229 in a closed ;
condition, a signal level is applied through conductor 231 to the display indicia array 122 to cause the illumination of a green lamp or panel therein and thus indicate to an operator that a normal operation is :-~
occurring. The closure of contacts 230, as shall be seen below, enables electrical safety valves 96 and 97 to be retained in an opensd condition where the flow is permitted to pass therethrough in a manner to be described subsequently. The energizing circuit for the relay 228 is supplied through either the contact set 227 or the grouped sets of contacts 218, 232 and 233 to a potential supply which has not been illustrated. The set of contacts 227 are automatically closed, as afore-said, when manual pump operation is the commanded mode through a switching of the mode switch associated with switch 176 as a~oresaid, ;
and whenever this .:

--- . -. , --, - , - . . . - , . ,. -: : .

~)7~
condition persists automatic energization of the relay 228 is initiated together with the operation of the pump. However, during automatic operation, the pump relay 228 is energized through the set of contacts 218, 232 and 233 which all must be in a closed condition Eor the pump to operate since an opening o~
any of these switches will cause the relay 228 to open whereupon the contacts 220, 229 and 230 open causing the pump to be dis~
abled, the green light to be ext:lnguished and the e:Lectrical safety valves 296 and 297 to be closed~ The con~act set 218 ~s -.
controlled by ~he dangerou~ flow relay 215, as aforesaid, and hence any time this condition occurs, the pump relay 218 is disabled. Similarly, contact set 232 is ln a closed condition ~:
only when the extruder screw 180 is operatlng as the same is .-driven by a relay which is actuated as a function thereof and hence if at any time during normal operation the extruder screw should jam, the set of contacts 232 will open to shut down the system~
Similarly, the contact set 233 wh.~ch. may~ operate in res~ponse tQ a delay as indicated, is controlled by th.e conditi.on of the hopper :
level relay 234 which is driven from th.e output o~ a deadband -amplifier as a function of a level control 236 withtn th.e h.opper . -~237 of the extruder. When the hopper has a sufficient level of compound to be cross-linked th.erein~ a normal level i5 provided from the level control 236 to the deadband amplifier 235 wh.ere-upon no output i6 provided to th.e hopper level relay 234, Under ~;
these conditlons, the deIayed contact set 233 rema~.ns clos:ed and the pump relay 228 iS energi.ze.d, However, sh:ould the level of polyolefin in the h.opp~r drop beIow-a specified amount, an out put is produced from the output of th.e deadband amplifier to energize the hopper level relay 234 and cause the delayed contact -set 233 to open and th.ereby disable the pump motor relay andhence the metering pump per se through the opening of switch contacts 220. The level control 236 for the hopper may be a ~C~751~

conventional mechanical or capacitive level detection device well known to those of ordinary skill in the art. Accordingly, it will be appreciated by those of ordinary skill in the art that the pump motor relay 228 is disabled any time a dangerous flow condition occurs, the level in the hopper 237 becomes tQo low-, or the extruder screw is not turning. Thls immedlately causes ~he pump motor to be disabled tllrough contact set 220, the green normal operating light to be extinguished through contactæ 224 while the electrical safety valves 96 and 97 are closed through the operation of safety relays 238 and 242 in response to the -opening of contacts 230.
The description of the pumping and metering compartment 62 set forth above has outlined how cross-linking agent is pumped from the storage facility for liquid cross-linking agent 61 into the feed vessel 89 by the action of the fill pump 88 and ~ -the operation of the fill pump 88 is strictly and precisely con- -trolled by levels residing within the feed vessel 89. Thereafter, the manner in which liquid cross-linking agent is d~awn from tne feed vessel 89 through the conduits 113 and 115 by the metering pump 90 and then supplied, after appropriate smoothing of the pulsed flow, to the flow transducer 95 wai~ described together with the manner in which the speed of the metering pump is controlled as a precise function of the difference between the flow rate within the system and the rate of use of material in processing. A similar description was also prov;`ded for the many ,-safety features employed within the sy~stem to ensure that a safe flow within the system is maintained. After the flow rate -is measured by the flow transduce-r 95, it is applied through the ; electric safety valve 96-to the flow- meter 98. The electric safety valve 96 may take any of the well ' - - . , . . - . ,-' iO'78188 ¦ known forms of this conventional class of device which functions to ¦ convey fluid therethrough only when po~ver is supplied to the actuating relay therefor illustrated as 23g. Therefore, as the relay 238 is ¦ connected throu~h conductor 239 to the contacts 230 which are controlle ~ :
I by the pump motor relay 228,it will be appreciated that any time power is not applied by the system or the metering pump is disabled, the electric safety valve 96 is immediately closed to close off the flow of liquid cross-linking agent through the system prior to the flow meter 98.
¦ The flow meter 98 may take any conventional form of flow .
l meter but the float type employing a glass tube for visual inspection of ¦ the flow is preferred to permit an operator to view the flow on a period c¦ basis so that not only may its rate be ascertained but its characteristic , . I visually Lnspected. The flow meter 98 corresponds to the glass tube ¦ flow meter illustrated as 18 in Figure 1. After passage through the ¦ flow meter 98, the liquid cross-linking agent being pumped through the system is supplied through conduit 241 through a second electrical safety valve 97. The electrical safety valve 97 may take the same forn I as the electrical safety valve 96 described above and the operatlng ¦ relay 242 therefor is energized through conductor 243 and the pump relay contacts 230 in the same manner as was descrlbed for the operati relay 238 of the eledrical safety valve 96~ This means that any time -power-is not applied to the system or the metering pump is disabled through the action of the pump relay 228, the electrical safety valve 97 ¦ Ls closed. The physical location of the electrical safety valve 97 has I
¦ been shown outside of the pumping and metering compartment 62; howe~ r, ~ its location is preferably just inside this compartment at a location whe . . ' ~"
. ' , , . ,'...... ~

~(~78~

the peroxide is in~ected from the cabinet into the base of the extruder. This means that any time the pump operation is termin-ated, peroxide injection will immediately terminate and virtually no drippings from the cabinet into the hopper ba~e will occur.
This has been indicated by the positioning of the electric safety valve 97 at the beginning portion of the injector tube for peroxide in the hopper cabinet. The injector tube 244 corresponds to the conduit 17 shown in Figure 1 and is positioned to inject liquid cross-linking agent into the base of the hopper.
The pumping and metering compartment indicated by the dashed block 62 is provided with a negative pressure venting means 99 to maintain a pressure therein which is less than atmospheric pressure while to additionally cause the venting of the cabinet.
Tn this manner, any liquld cross-linking agent which should spill or evaporate within the environment of the pumping and metering compartment 62 will be quickly vented to a safe environment, While the negative pressure venting means 99 has been schematically illustrated, it should be noted that seal proof construction is used throughout and that ducting to an external environment carried out through the port includes essentially a one way flow from the interior and metering compartments 62 to its external environment.
The negative pressure venting means 99 has been illustrated in Figure 3 as being driven by a fan blade 246 which in turn, is driven by a motor 250 which is located externally with respect to the pumping and metering compartment. The motor 250 is energized through a relay contact set 251 and a current sensing device 252, the potential supply to the motor not being shown. Thus, it will be seen that whenever the relay contact set 251 is in a closed condition, the fan motor 250 will be energized to thus energize the ~LC978~

negative pressure venting means 99, The relay contact set 251 i$
actuated by the condition o~ the vent-~ng relay 253 which is connected across the potential supply 105 directly through con~
ductor 106 and indirectly through relay contact sets 254 and 255 to the conductor 107. Accordingly, it will be appreciated by thos.e of ordinary skill in the art that so long as contact sets 254 and 255 are in a closed condition, the venting relay 253 will be energized to close contact set 251 and hence energize the venting motor 250. The contact set 255 is connected as indicated to the instantaneous relay 82 wlthln the fire indicatlng means 79 and hence this contact is opened by the instantaneous acting relay ~2 only when ~umes indicating a combu$tion situation have been indicated. Thus, when such fumes are detected it will be seen that contact set 255 is opened to deenergize the venting relay 253 to cause the contact set 251 to open and hence, deenergize the venting motor 250. Similarly, contact set 254 i5 energized as a function of the current sensor 252 in the same manner as a relay contact set. Thus, whenever a normal current level is being sensed by the current sensor 254 in well known manner, contact set 254 is energized to energize the venting relay 253 and hence to continue the motor 250 in an energized cond~tion. How~-ever, when excess current is sensed by the current sensor 252, the contact set 254 is opened to de-energize the venting relay 253.
It will be appreciated by those of ordinary skill in the art th.at should excess current be sensed by the current sensor 252, the venting motor 250 is operating improperly and hence, appropriate -:
ventilation i.s not occurring. There~ore, to avoid ~urther damage, .
the venting relay 253 is opened to disable the motor 250 and an .-.
additional contact set 256 is closed, The contact set 256 is 30 connected between ~

- 45 - .

'~ ' ' a potential supply indlcated by the horizontal line and the conductor 257 to the temperature ventilation alphameric indicia within the alphameric indicia display array 21 and through the conductor 258 to the re~
indicia within the warning light array 122. This means that both the temperature ventilation indicia wi-thin array 121 will be illuminated together with a flashing red warning light and the horn 129. Accordingly, it will be appreciated that whenever a failure of ventilation motor 250 is de-energized while should a fire condition any place :in the system be detected, de-energization of the venting motor 250 occurs through direct de-energization of the switch contacts 255.

In a similar manner, a heat sensor 260 is disposed within the ;
pumping and metering compartment 62 to monitor the temperature therein.
The heat sensor 260 may take the form of a conventional thermal couple ... .... .
or the like and is connected as indicated to energize a relay 261 any time a high temperature condition is detected. Upon energization9 the relay 261 closes contact set 262 to connect a supply indicated by the horizontal line annotated V through conductors 263 and 257 to the temperature ventilation indicia within the array 121 and the red warning light within the array 122 to cause both indicia to be illumina-ted and sound the warning horn 129. Accordingly, it will be appreciated by those of ordinary skill in the art that should either the ventilation or an abrupt rise in temperature occur within the pumping and metering compartment 62, a warning of abnormal conditions is issued to the operator together with the illumination of advisory indicia specifying the precise condition which has caused the warning indicia to be issued.

.~.".': ' ' .

~ '.

.. ~ , ~. . - . .

All parts within the pumping and metering compartment 62 which come in contact with the metered liquid are strictly non-corrosive and neutral in construction with regard to the product being provided and such materials may be made from stainless steel, glass, TeFlon, polyethylene, etc. In addition, the connecting ducts for the insulation are also preferably formed of stainless steel and heavy metals such as copper are deliberately avoided. All electrical apparatus contained within the pumping and metering compartment 62 are either oF an explosion type design or are inherently safe and the power levels selected are chosen so as to be incapable oF arcing. Similarly, all feed throughs oF conduits and electric cables utilize leak proof gaskets so the integrity oF the environment on either side of -the gasket is maintained. Furthermore, a catch basin lO0 is positioned within the pumping and metering compartment 62 so as to underlie all components handling metered liquid and hence, serves to prevent the leakage of material out of the container. A sump 265 is provided within the catch basin lO0 so that all fluid which has been caught thereby will be collected in the sump whereupon the level thereof may be sensedO
More particularly, the sump is provided with a pneumatic or similar level monitor 266 ~vhich is arranged to close a se-t of con-tacts 267 when-ever the level in the sump exceeds a predetermined level. When the contacts 267 are closed, potential is applied from the source indicated as V through conductor 26E~ to illuminate the alphameric indicia within the alphameric indica array 121 annotated LEAK. In addition, as indicated by the conductor 269, the red flashing indicia within array 122 is also illuminated to cause a red flasing warning to be issued and a sounding of the horn 1 2g.

,~
. ~.

, .

.

10~78188 . ~' Fire detection and correction equipment may also be provided within the pumping and metering compartments 62 through the provisio~
of an ionization chamber 270 therein which acts to detect gases associated l,vith combustion. The ionization chamber 270 may be the same as ionization chamber 78 described above and is connected through conducSor 271 to the fire indicating means 79 described above.
This means, it will be recalled, acts in response to the detection of a fire condition to immediately terminate the operation of the ventilatio system through immediate acting relay 82 and the contact set 255 while - acting through the operation of delayed relay 83 to initiate the operationof extinguishing equipment. In the case of the pumping and metering compartment 62, an extinguisher flask 272 is mounted on the side of the pumping and metering compartment 62 as shown and when -enabled , by the output of the slow acting relay 83 through conductor 273, causes extinguishing fluids to be vented into the system through the conduit 274 ¦ It should additionally be noted that any time the immediate acting relay - 82 within the f~re indicating means 79 is actuated, a slgnal is supplied thereby through the conductor 275 to cause the red warning indicia ¦ within the indicia array 122 to be actuated while a fire horn 276 is ¦ additionally actuated. When fire indicating means 79 are ernployed ¦ within the system, additional ionization chambers such as 277 may be disposed about the syst em to warn of externally developed fire hazards and to cause extinguisher fluid to be supplied to hazardous areas handli ;
metered nuids, -~5 Though not previously described, the switch 17~ which acts, as aforesaid, to determine whether the error signal is developed as a -48- '~
. , . .
, ' .' '' ~7~18~3 function of the speed of the extruder screw or the speed of the actual production line is ganged in the manner indicated to the switch 278 associated with the alphameric indicia display 121.
Accordingly, this switch 278 thus defines the mode of synchroni~
zation being employed to the alphameric indicia display and accordingly, will couple the voltage source indlcated by the horizontal line annotated V to the appropriate one o~ the con-ductors 279 or 280 to cause the approprIate :lndlcla, extruder sync or line sync, to be illuminated to thux apprise the operator as to the method of synchronization employed to develop the error signal whlch controls the speed of the metering pump. When the extruder sync indicia is illuminated, the blue warning indicia within the array 122 is illuminated as indicated by the conductor 281 while when line production synchronization is being employed, as indicated by the conductor 282, the white indicia associated with the array 122 is employed.
An event recorder 290 is also provided so that a con-tinuous record is made of the critical warnings issued as a function of time as well as the modes of operation taking place when such warnings were issued. The timing function is provided by means of a synchronous motor 291 driving the record paper at a speed which is exactly proportional to time. Similarly, the ~-occurrence of the red and orange warnings, regardless of origin, -~
are the critical factors which need be noted in a continuous record of operation and the energized or de-energized condition oE
the red and orange display indicia within the array 122 may be conveyed through conductors 292 and 293 and recorded on appropriate ones of the tracks of the six track event recorder 290. Similarly, as the nature of the synchronization employed to develop the error signal is defined as a function of either the actuated condition ~ - - . , , - .

: of the blue or white warning lights, the enabled or dis.abled level thereof ~ay be supplied from the array 122 through conducto~s 294 and 295 and recorded onto additional independent tracks of the six track event recorder serving as the event recorder 290, Finally, the condition oE switch 176 deEining either the manual or automatic mode oE operation may be gated to the base of the warning light array 122, through means not shown ? ~nd conveyed - for recording purposes on an additional track of the six track event recorder through the conductor 296, Thus, in this manner~
a continuous record is malntained as: a function of time b~ the event recorder ~hich record includes the modes of operation initi-atedl the type of synchronization employed therewith and the nature of the dangerous conditions which occurred during such operation~ -Such records may be quite important in further analyzing the .
operation of the instant embodiment of the invention wherein highly volatile cross-linking agents are supplied from a closely controlled and monitored supply system and injected into the base of an extruder under ambient conditions~
The p~esent invention is viewed as highly advantageous - :
~ 20 since it permits precisely metered amounts of a liquid agent such .~
- as an organic peroxide or any other highly volatile liquid to be .~.
: injected under ambient conditions for combination with other com-pounds in a manufacturing process under circumstances which require ~:
no preliminary preparation of materials-. Furthermore, the supply ;~ . -system proposed is e~quisitely configured for the safe handling of highly volatile materials such as: volatile cross-linking agents because th.e metered output thereof is controlled as: a function of an error signal developed bet~een the rate at which liquid cross-linking agent is injected and the rate at which the same is bei.ng used during processing. This means, that under no ~7~ 8~3 conditicnswill more cross-linking agent be delivered than is effectively being employed so that a dangerous build up of volatile material is avoided. Furthermore, through the provisions of internal monitoring and safety features as well as arranging the fluid conducting components within the pumping and metering cabinet l and on an inclined plane upwards towards the output, should arly dangerous conditions arise, the cut-off of injected material from the extruder is immediate and also self-imposed by the system. Furthermore, the supply system per se provides an operator with timely warning~ so that abnormal conditions which become hazardou~ may be timely corrected and alarm features calculated to call immediate attention to the condition are employed. Thus, while possible devia-tions in the metering rate of the liquid injected are constantly monitored and automatically corrected, they are also displayed and recorded so as to be readily available for operator analysis. ~

The supply system employed also warns of dangerous flow,- ;
maximum flow and minimum flow conditions so that flow rates which are either hazardous or improper are immediately called to the attention of the operator and should a hazardous condition exist, the metering pump 2û
is terminated to immediately cure the condition. Similarly, maximum and minimum level contrb~s within the feed vessel 89 are monitored so that both overflow conditions and conditions wherein the system is about to run out of cross-linking agent are indicated to the operator while the fill pump 88 is terminated to permit the condition to be corrected. Similarly, in areas where the volatile cross-linking agent are handled per se, venting is provided and monitored while refrigera-tion techniques with temperature monitoring are also employed to avoid hazardous conditions. In a similar manner, the metering pump which controls injection is interlocked with the operation of the extruder or ~8~

a slmilar processin~ device so that injection is precluded unless processing operations are occurring and the only exception to this is provided in a manual mode of operation which is necessitated for testing and calibration procedures. ~lectrically operated valving is also provided to ensure immediate cut ofE oE the in-jected cross-linking agent should power failure or termination o~
the metering pump arise and combustion detection equipment to-gether with automatic extinguishlng equipment may be employed in appropriate portion of the supply system to further reduce the chance of accidental ;Eire or the like, Similarly, the use of the inventive supply system in connection with the extrusion of ~
polyolefin compounds or the like is highly advantageous ~ecause `
using a cross-linking agent in its volatile form in the example -cited is much less expensive than forms of the cross-linking agents which are currently employed, does not require special preparation and the combination may be initiated under ambient conditions where-in the extruder per se is employed to mix the same into a homo-geneous relationship while cross-linking may be per~ormed on a continous processing basis.
~hile the invention has been disclosed in con~unction `
with a rather specific embodiment which is rendered highly de-tailed due to the need to show specific safety and monitoring fea-tures, it will be appreciated by those of ordinary skill in the -art that many variations and alternatives to the specific em-bodiMents set forth may be employed without deviating from the teachings of the instant invention. More particularly~ while specific sensors and monitoring techniques are disclosed herein, it will be apparent that alternate forms of sensing or .. , ~ . , . .- - . . ., -, . . : ::

monitoring devices may be employed in association with different forms of monitoring techniques. Furthermore, while a great number of safety and monitoring features were disclosed in conjunction with the supply system for the volatile cross-linl<ing agent disclosed, it will be appreciated by those of ordinary skill in the art that when the supply system is employed for diFFering types oF cross-Linking agent or volatile materials, either a greater or lesser number oF saFety and monitoring Features may be utilizecl dependillg upon the speciFic application contemplated and the practical requirements dictated by 1û circumstance. In addition, while the use oF the instan-t supply system in conjunction with an extruder is highly advantageous, it will be seen that direct combination of a volatile agent or cross-linking agent as provided by the supply system may occur in an advantageous manner with other types of processing equipments where the precisely metered output of the instant supply system may be employed to great advantage.
Therefore, this aspect of the instant invention should not be viewed as limited to use with an extruder or any of the specific combinations set forth in conjuction with the instant exemplary embodiment.

Accordingly, while the invention has been described in conjunction with a rather specific exemplary embodiment thereof, it ~ ;
will be understood that many modifications will be readily apparent to those of ordinary skill in the art; and that this application is intended to cover any adaptations or variations thereof. Therefore, it is manifestly intended that this invention be only limited by the claims and the equivalents thereof.

~'~,,'.

Claims (27)

1. Apparatus for supplying a volatile Liquid at a precisely controlled rate to processing equipment, said apparatus for supplying comprising:
extruder means included in the processing equipment employing said volatile liquid in processing operations occurring therein, said extruder means exhibiting a determinable rate of operation and the rate of consumption of volatile liquid therein being a function of said rate of operation of said extruder means;
means for storing a supply of volatile liquid;
feed vessel means;
means for inserting quantities of volatile liquid from said supply into said feed vessel means;
means for injecting volatile Liquid at ambient temperature and atmospheric pressure to an input means of said extruder means at a controlled rate, said means for injecting being in fluid communi-cation with said feed vessel means and operating at a controlled rate;
means for continuously producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting;
means for continuously producing a second signal representative of said rate of operation of said extruder means; and means, for controlling the rate of operation of said means for injecting as a function of the difference between said first and second signals.

2. The apparatus according to Claim 1 wherein said means for injecting comprises metering pump means and said means for producing a first signal includes flow rate transducer means, said metering pump means being connected to said feed vessel means and acting to pump volatile liquid from said feed vessel means to said input means through said flow rate transducer means.

3. Apparatus for supplying a volatile liquid at a precisely controlled rate to processing equipment employing said volatile liquid in processing operations occurring therein, the processing equipment exhibiting a determinable rate of operation and the rate of consumption of volatile liquid therein being a junction of said rate of operation of the processing equipment, said apparatus for supplying comprising:
means for storing a supply of volatile liquid;
feed vessel means;
means for inserting quantities of volatile liquid from said supply into said feed vessel means;
metering pump means for injecting volatile liquid at ambient temperature and atmospheric pressure to an input means of the proces-sing equipment at a controlled rate, said metering pump means being connected to said feed vessel means and operating at a controlled rate to pump volatile liquid from said feed vessel means to said input means of the processing equipment;
transducer means for producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting, said transducer means being disposed intermediate said metering pump means and said input means and having volatile liquid to be injected pass therethrough;

means for continuously producing a second signal representative of said rate of operation of the processing equipment;
means for controlling the injecting rate of said metering pump means as a function of an error signal;
means for comparing said second signal representing a rate at which the processing equipment is operating and said first signal developed from said flow rate transducer means representing the flow rate of volatile liquid being pumped through said flow rate transducer means and producing an error signal corresponding to the difference therebetween:
means for applying said error signal to said means for controlling the speed of said metering pump to control the injection rate of volatile liquid; and means for evaluating said error signal and indicating a detection of a dangerous flow condition.

4. The apparatus according to Claim 3 wherein said means for evaluating acts to terminate the operation of said metering pump means upon a detection of a dangerous flow condition.

5. The apparatus according to Claim 3 wherein said means for evaluating additionally includes means for detecting minimum arid maximum flow conditions.

6. The apparatus according to Claim 5 additionally comprising means responsive to said means for evaluating for additionally indicating the presence of maximum and minimum flow conditions.

7. The apparatus according to Claim 4 additionally comprising valve means disposed intermediate said metering pump means and said input means, said valve means being responsive to a termination of said metering pump means to cut off the flow of volatile liquid to said input means.

8. The apparatus according to Claim 3 additionally comprising means for disabling the operation of said metering pump when said processing equipment is not operating.

9. The apparatus according to Claim 3 wherein the processing equipment includes an extruder and said means for detecting the rate at which the processing equipment is operating including means for measuring the speed of said extruder.

10. The apparatus according to Claim 3 wherein the processing equipment includes product forming means and said means for producing a second signal representative of the rate at which the processing equipment is operating including means for measuring the rate at which product is produced by said product forming means.

11. The apparatus according to Claim 3 wherein the processing equipment includes an extruder having product forming means connected to the output thereof, said means for producing a second signal representing the rate at which the processing equipment is operating including means for selectably measuring the speed of the extruder or the rate at which product is produced by the product forming means.

12. The apparatus according to Claim 1 wherein said extruder means includes a hopper for polyolefin compound connected to an input thereto and said means for injecting a volatile liquid being connected to a base portion of said hopper.

13. The apparatus according to Claim 1 wherein said volatile liquid may comprise a cross-linking agent.

14. Apparatus for supplying a volatile liquid at a precisely controlled rate to processing equipment employing said volatile liquid in processing operations occurring therein, the processing equipment exhibiting a determinable rate of operation and the rate of consumption of volatile liquid therein being a function of said rate of operation of the processing equipment, said apparatus for supplying comprising:
means for storing a supply of volatile liquid;
feed vessel means;
fill pump means for pumping quantities of volatile liquid from said storing means into said feed vessel means, said feed vessel means being in fluid communication with said means for injecting;
means within said feed vessel means for determining a maximum level condition;
means responsive to a detection of said maximum level condition for terminating operation of said fill pump means;
means for injecting volatile liquid at ambient temperature and atmospheric pressure to an-input means of the processing equipment at a controlled rate, said means for injecting being in fluid communication with said feed vessel means and operating at a controlled rate;

means for continuously producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting:
means for continuously producing a second signal representative of said rate of operation of the processing equipment;
and means for controlling the rate of operation of said means for injecting as a function of the difference between said first and second signals.

15. The apparatus according to Claim 14 additionally comprising means responsive to a detection of said maximum level condition to initiate indicia representative of this condition.

16. The apparatus according to Claim 14 wherein said means within said feed vessel means also acts to determine the presence of minimum and normal levels therein.

17. The apparatus according to Claim 16 additionally comprising means responsive to a detection of said minimum level condition to initiate indicia representative of this condition.

18. The apparatus according to Claim 16 additionally comprising means responsive to a detection of a minimum level condition and an absence of a normal level condition within said feed vessel means for terminating operation of said fill level pump.

19. Apparatus for supplying a volatile liquid at a precisely controlled rate to processing equipment employing said volatile liquid in processing operations occurring therein, the processing equipment exhibiting a determinable rate of operation and the rate of consumption of volatile liquid therein being a function of said rate of operation of the processing equipment, said apparatus for supplying comprising:
means for storing a supply of volatile liquid;
feed vessel means:
fill pump means for pumping quantities of volatile liquid from said storing means into said feed vessel means, said feed vessel means being in fluid communication with said means for injecting;
means for controlling temperature within said feed vessel means, said means for controlling temperature maintaining said feed vessel means in a coded condition;
means for injecting volatile liquid at ambient temperature and atmospheric pressure to an input means of the processing equipment at a controlled rate, said means for injecting being in fluid communication with said feed vessel means and operating at a controlled rate;
means for continuously producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting;
means for continuously producing a second signal representative of said rate of operation of the processing equipment; and means for controlling the rate of operation of said means for injecting as a function of the difference between said first and second signals.

20. Apparatus for supplying a volatile liquid at a precisely controlled rate to processing equipment employing said volatile liquid in processing operations occurring therein, the processing equipment exhibiting a determinable rate of operation and the rate of consumption of volatile liquid therein being a function of said rate of operation of the processing equipment, said apparatus for supplying comprising:
means for storing a supply of volatile liquid;
feed vessel means;
means for inserting quantities of volatile liquid from said supply into said feed vessel means;
means for injecting volatile liquid at ambient temperature and atmospheric pressure to an input means of the processing equipment at a controlled rate, said means for injecting being in fluid communi-cation with said feed vessel means and operating at a controlled rate;
means for continuously producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting;
means for continuously producing a second signal representative of said rate of operation of the processing equipment;
means for controlling the rate of operation of said means for injecting as a function of the difference between said first and second signals;
means for enclosing said means for inserting, said feed vessel means and said means for injecting within a closed environment; and means for venting said closed environment and establishing a negative pressure therein.

21. The apparatus according to Claim 20 additionally comprising means for sensing the operation of said venting means and providing advisory indicia upon failure of said venting means.

22. The apparatus according to Claim 20 additionally comprising means for sensing the temperature within said closed environment and providing advisory indicia upon a detection of a temperature exceeding a predetermined level.

23. The apparatus according to Claim 20 additionally comprising means for sensing combustion gases within said closed environment and providing advisory indicia upon a detection of said combustion gases and means responsive to a detection of combustion gases for inputting extinguishing fluids into said closed environment.

24. The apparatus according to Claim 20 additionally comprising catch basin means in said closed environment underlying said means for inserting and said means for injecting, said catch basin means including means for detecting the accumulation of liquids in said catch basin means and providing advisory indicia upon a detection of this condition.

25. Apparatus for supplying a volatile liquid at a precisely controlled rate to processing equipment employing said volatile liquid in processing operations occurring therein, the processing equipment exhibiting a determinable rate of operation and the rate of consumption of volatile Liquid therein being a function of said rate of operation of the processing equipment, said apparatus for supplying comprising:
means for storing a supply of volatile liquid;
feed vessel means;

means for inserting quantities of volatile liquid from said supply into said feed vessel means;
means for injecting volatile liquid at ambient temperature and atmospheric pressure to an input means of the processing equipment at a controlled rate, said means for injecting being in fluid communication with said feed vessel means and operating at a controlled rate;
means for continuously producing a first signal representing the rate at which volatile liquid is being injected to said input means by said means for injecting;
means for continuously producing a second signal representing of said rate of operation of the processing equipment;
means for controlling the rate of operation of said means for injecting as a function of the difference between said first and second signals:
means for enclosing said means for storing within a closed environment;
means for controlling temperature within said closed environment; and means for sensing combustion gases within said closed environment and providing advisory indicia upon a detection of said combustion gases.

26. The apparatus according to Claim 25 wherein said means for controlling temperature comprises means for cooling said closed environment.

27. The apparatus according to Claim 25 additionally comprising means responsive to a detection of combustion gases for inputting extinguishing fluids into said closed environment.