US1697341A - Orifice element and system and apparatus utilizing the same - Google Patents

Description

Jan. 1, 1929.

G. CAMPBELL ORIFICE ELEMENT AND SYSTEM AND APPARATUS UTILIZING THE SAME Filed June 13, 1925 3 Sheets-Slide? 1 11v VIiNTOR av Mk I A TTORNE rs.

I I a Jan. 1, 1929.

G. CAMPBELL ORIFICE ELEMENT AND SYSTEM AND APPARATUS UTILIZING THE SAME 3 sheets fimei 2 Filed June 13, 1925 INVENTOR A TTORNEY5,

Jan. 1, 1929. 1&97343 G. CAMPBELL ORIFICE ELEMENT AND SYSTEM AND APPARATUS UTILIZING TH SAME 3 Sheets-Sheet 5 Filed June 15, 1925 Patented 1, 1929..

UNITED STATES v Ti-zu'r OFFICE.

GRANT CAMPBELL, OF SHORT HILLS, NEW JERSEY, ASSIGNOR TO' CAMPBELL ENGI- NEERING COMPANY, OF SHORT HILLS, NEW JERSEY, A CORPORATION OF NEW JERSEY.

ORI'FICE ELEMENT AND STEM AND APPARAEUS UTILIZING THE SAME.

Application filed Jui1e 13, 1925. Serial No. 86,928.

This invention is a novel orifice element and system and apparatuses utilizing the same. The novel orifice element and system of orifices to be described, are adapted to a wide field of practical application, and the characteristic features are claimed irrespective of any particular utilization. In describing the invention various methods and apparatuses employing the orifice element and system will be described, and each of these per se is also claimed as novel, in some cases lrrespective of the particular characteristics of the orifice element or system itself. In describing particular uses or em bodiments of the present invention it is not intended to limit the same to such uses and embodiments, as the general features can readily be employed or developed for an extended variety of uses. Among the various practicalemploymentspf the invention, having reference to flow of fluids, including liquids, gases and vapors, are the following: vapor traps, for example to remove liquid from vapor, such as removing water from arate points of delivery; fluid ejeetors;

mufllers, etc.

In the accompanying drawings, showing a number of embodiments of the present invention the figures are more or less diagram,- matic, and all of them may be considered as elevation views, in many cases partly broken away or in section to indicate interior construction.

Fig. 1 shows an embodiment of this invention, adapted to serve as a vapor trap, for

example for removing water from steam; the samebuilt up from a combination of orifice elements constituting an orifice system embodying the present invention, and illus-.

' trating the system of combining such elements with each other and with vother piecesof apparatus, and illustrating as well a novel method and trap for removing liquid from vapor. Fig. '2 is a detail view showing a preferred detail of, arrangement, namely with graded sizes of orifice nozzles, as employed in Fig; 1. Fig. 3 is a modification showing in tandem a system of orifice ele ments of different design from those shown in Fig. 1. Fig; 4 shows asteam or vapor t-rap'of different design from that in Fig. 1. Fig. 5, on a smaller scale, shows the same elements as in Fig. 4, with further connected elements.

Fig. 6 shows an embodiment of the present invention applied to fluid meters, adapted for determining, controlling or measuring the rate or quantity of flow .of various fluids, such as steam. Fig. 7 indicates a different form of fluid meter embodying this invention. Fig. 8 shows a still further form of fluid meter embodying the present invention. Fig. 9 shows-a pressure reducing system,

operating also as a mufller, constructed in I of any passage or chamber containing steam or vapor from which it is desired to remove. water. or condensed vapor. This pipe is threaded and has connected to its lower end the apparatus constituting the present invention. A series or system of units or elements 12, which I term orifice elements, are interconnected with each other and attached at the lower end of pipe 11. -The orifice elements are shown connected in" succession or tandem, and it is a feature of this invention 'thatthese may be in-the form of identical units, connectible in various ways and combinations, with each other and 'other apparatus. Four orifice units 12, are shown in Fig. 1, connected intandem, the top one connected to the pipe 11.

Each element 12 COIlSlStS of a main or chamber wall 13, shown ofa bulging or a with orifice nozzles of progressively increas ing aperture at the throat 18. The nozzles may 'take different forms, for example there ma be a tapered approach 19 to the throat an a flaring getaway 20. To lend greater flexibility of use to the units 12 each of them may be formed with a tapped boss 21 in the chamber wall, for connection to a gage or other apparatus. The top" unit 12 is shown with the oss 21 closed by a plug 22, and this is true of the others, with the exception of one of the intermediateunits,

- which may ;be advantageously connected, by

a pigtail siphon or other connection 30, with a pressure gage or indicator 31. The threaded lower exit of the final or bottom unit 12 may be connected as shown by a usual formof threaded fitting or coupling 23 to a pipe 24 leadingto any desiredpoinfior to waste.

The described assemblage affords a simple and positive trapping device. The water present'is completely dischar ed at the final .orlowest exit, after accumu ating-ineachlmit and bein forced throughthe successive nozzles. nly a minor or a negligible amount of steam is permitted to escape at times when there isn'o water-present. The discharges from unit to unit are at" successively decreasing stages of. pressure, from thetinitial pressure in pipe 11 to the final discharge pressure. At each sta e the pressure drop is only a fraction 0 the entire #drop, and the orifices effectively dischar e any accumulated water, while efi'ective y controlling and limitin steam passed through the amount of unit to unit. Owing to the progressively lower pressures in the successive units re-evaporationof the progress'in liquid readily takes place, and the use 0 a plurality of units in tandem affords maximums,- re-eva oration of the liquid being discharged; 7 this way clean low-pressure steam may be finally" delivered fromthe trap, which maybe available for heating or other purposes. The operation is automatic and self adjusting'to changes of conditions, and removal of water is'completely efiected- Com ared with "steam traps heretofore known the described trap is further superior in that, no moving parts or its-a r qu e The apparatuses low ofco'st, and readily assembled, attached the chem The orifice mem and used, and repair costs are substantially eliminated. The most advantageous number and siz of units, and sizes of the orifices thereof, for any given conditions, are readily determined by consideration of the initial steam. pressure, and the expected quantity of water to be discharged. The successive orifices may be of uniform size throughout the system,- but it is preferred toarrange them with ro 'ressivel increasin sizes toward the final discharge, as indicated at 18, 18" and 18 in Fig. 2. Thereby the first nozzle, controlling the total discharge rate, causes themain drop of pressure in the system, the

subsequent nozzles progressively lowering the'pre'ssure until the final nozzle dischar es into the lowest pressure of the system, wh1ch may often be atmospheric pressure.

the pressure in any chamber between the first and last orifices, for example, as shown,

that in the second unit, that is, in the chamber between the first and second orifices. Knowing the intermediate pressure and the initial pressure, and the character of the orifices between, the relative rate of flow through the, system is determinable, byformula, or by special calibration of gage. The orifice elein'ent hereof may be described as a hollow structure, or vessel built up if desired but preferably unitary, being constructed preferably of metal, its walls enclosing a chamber, and having at least two openings, the entrance and the exit, provided with means by which the element or unit may be coupled up to similar units or to other apparatus, and, an orifice member or nozzle suitable oint so that fluids passing through r fromentrance to exit must traveing contained or supported 'at a erse the-orifice. The nozzle is preferably machined or drilled with a scientifically designed and sized orifice, and, while it might in some cases'be integral, is preferably removable and-replaceable by other nozzles with orifices of difl'er'ence size or character. While the nozzle might be difi'erently located it ma. advantageously be within the exit en v as shown, thereb permitting the mode of coupling of .unitsm tandem and connection to other ap a'ratus or iping as shown. r or nozz e may be of dif-' ferent types. Instead of the tapered-flared nozzle, as shown, there may be a simpleperrorated washer or plate clamped within the unit; orfa thimble type orifice member may be driven into a tapered opening in-the unit;

the first mentione giving satisfactorily accurate results with a tan em arrangement;

The bulging or' pear shape oforificeunit,

as in'Fig. I, is advantageous in its increased 1 capacity, better operation, andwider utility,

but this is not always necessary as orifice units such as. 12* in Fig. 3 having conical The purpose of the gage 31 is to indicate 3 I walls will frequently sufiice, these having threaded entrances and exits v and 16 Also, while theunit 12 shown in Fig. 1, isprovided with a hexagonal bead 15 at the entrance end and a tapped boss 21 at theside, the arrangements may be extensively varied to suit requirements. 4 and 5 the unit 12 is provided with an additional hexagonal head 35, near the exit end, increasing the facility of assemblage,

especially for applying a wrench to units of.

, large size, while theunit 12 is formed with a large boss 36at one side for the purpose of.

providing a second inlet, to which may be .connected a unit 12? analogous to any of either receive froin a pressure line or discharge to a. suctlon 11118. The four orifices in Fig. 1 have three chambers between them, and cause four'stages of pressure drop, the flow at each orifice depending on the character of orifice and the pressures above and below it. The imits and orifices preferably trend downwardly, so that any water present quickly reaches the orifices and is discharged. The liqui'd flows onward ahead of the gas and minimizes steam waste. The water will usfiallybe partly or wholly, reevaporated during its passage to the final outgo pipe or discharge, so-that much steam is afforded for collateral uses, heating etc.

Successive orifices of uniform .area give less satisfactory results .than graded areas of increasing size toward the lower pressures. By the ,latter the successive pressure drops may be substantially equalized. Thus if 42% drop in absolute pressure is desired in passing through each nozzle, the orifice areas may be successively 75% larger, more or less, as roughly indicated in Figs. '2 and 3. This is calculated as follows. 42% drop of absolute pressure means in the ratio of'l to .58, or a volume increase to 1+.58 or- 1.72, an increase of 72%. The successive orificesare of gas.

therefore 72%; larger progressively to take care of the progressively increasing volume For traps these percentages are satisfactory, and the arrangement tends to pass the same amount of steam or other vapor at,

each stage if no liquid is present. With an.

initial steam pressure of 113.4 pounds per square inch, four orifices, of areas .01944; .03345; .05767 and .09943 will discharge steam at atmospheric pressure, assuming no liquid present, at the-rate of about 128' pounds per hour. Higher ressures may require additional larger or ces at the low" Thus in Figs trapped excludes passage will indicate the absence of water.

In any case the presence of water to be i of steam, and the system can be calculate to take care'of the water under all circumstances while minimizing the waste of steam. The flow of water through the orifice system is of course' at a much greater rate, in pounds, than of steam, making the invention very effective as a trap. The pressure gage indicates the. conditions, on the following principles. .The rate of flow of steam or other gas through an-orifice into a pressure not greater than 58% of the initial absolute pressure may be considered as a direct function of the initial absolute pressure, while on the other hand, the rateof flow of water,.not hot enough to reevaporate, through an orifice, is a direct function of the square root of tliedifi'erence" in pressures. If then steam only is present in the orifice system and the orifices are properly proportioned, the pressure gage will stand at'a' definite point, for example 42% of the absolute ressure in the previous stage, which may e the boiler pressure. Therefore the gage standing at thispoint On the other hand withonly cold water in the sys tem, since the rate of flow must be the same through each'stage or chamber,,t,he absolute pressure drop. through the successive nozzles will be about in the ratio of 3 to 1. This is calculated from the knowledge that the flow is a function of the s uare' root of the drop of pressure multiplie by the area of the orifice. The orifices increasing progressively in area in the proportion 1 to 1.72, calculation shows-that the pressure drop through successive nozzles is as 2.96 to 1, or about 3 to 1. Therefore the initial pressure, as: sumed as 113,4 pounds, must represent the total cold water pressure drop through four nozzles. The successive drops through the four nozzles are in the ratio of 27 to 9-to 3 to 1, and apportioning the total drop will give successive dro s of about 76 then 25 then 9 then 3. Wit only cold water in the system] therefore the successive pressures will be about 113.4 then 37.4 then 12 then 3 -then 0; whereas with only gas or steam the successive pressures will be about 113:45-then 59.6 then 28.4then 10.6 then '0. As stated therefore the pressure gage, applied at any.

intermediate stage, will indicate the cond i-' embodiment of this invention the orifice system may be supplemented by a' strainer or meansof any sort located in advance of the orifices to exclude from the orifices any scale, fiber, compounds or other sediment or foreign matter, and thus avoid clogging.

Having now described the orifice elements or units, and their action when connected ,in tandem, and one embodiment, the trap of Fig. 1, I will proceed to describe other illustrative embodiments.

The trap of Figs. 4 and 5 is a special one devised to drain moisture. from the exhaust pipe, for example, of a prime mover, and discharge it at some desired point, perhaps at a greater elevation than the source, in cases where the exhaust pressure is itself insufficient, with a simple orifice system, to force the water to the desired point. This embodiment utilizes steam from another point to elevate the exhaust water. A pipe 34 is shown, leading for example from the drip connection of a throttle valve, dispe sing with any other trap at that point. This conducts the steam into orifice element 12, which is coupled to a special two-entrance element 12, the discharge coupling 23 of which leads by pipe 24 to the desired point, for example toa feed water heater. To the second entrance 36 of element 12 is coupled an element 12, containing orifice nozzle 17, and receiving water from the exhaust by down pipe 37, which water is delivered The outlet greatly elongated flared exit 20*, extending through element 12 and into 'the exit 16 thereof, forming an ejector: This embodiment therefore illustrates not only a special trap but an advantageous built-u ejector, capable of general uses, and avallable by mere assembling of stock parts. The steam under pressure delivered through the ejector tube 20 produces suction in the chamber 12, drawing the water therefrom, and lifting it to the desired point. This simple combination therefore serves doubly, first to receive and utilize thewater'collected at the throttle drip, .and second to trap and utilize the waste water from the exhaust, keeping both sets of pipes dry. The apparatus will operate even with moderate vacuum in the exhaust pipes. The combination is believed ,to be new in principle irrespective of the makeup of structure; thus an ordinary ejector may be used,i with connections analogous to those shown, enabling the drip steam from the throttle to be used as a motive power to lift low pressure water or discharge it against pressure, performing the service of a pump as'well as two traps. When the drip steam pressure is excessive, additional orifice elements or a valve 38 may be introduced between element .12 and the'source of the steam, to reduce the pressure to the best the needs of the ejector.

- purposes.

To prevent high pressure enter-.

from the throttle by indicating the pressure and enabling the flow to be regulated to The exhaust main may be provided with a differential gage for indication purposes.

As already stated, traps such as thevapor traps described, constitute only one instance of utility of the present invention in apparatus wherein fluids at higher pressures are subject to controlled 'escapement to lower pressures for-various purposes, other embodiments having been enumerated. Next will be described theembodiment of the present invention in fluid meters, with the three illustrations shown in Figs. 6,7 and 8.

The purpose of such meters is to indicate the rate of flow of the fluid (gas, vapor or liquid), the .total quantity passing through the meter being determinable from the rate of flow. For ordinary commercial metering purposes the flow is regulated at a 'point.

after passing the meter according to variations of demand, the drop in pressure usually being quite small, and a differential pressure gage, such as a U-tube, being desirable. The invention however is also available for a second class of meters, wherein the regulation is either before or after passing the meter, and wherein'the drop in absolute pressure is large, for example to 58% or less of the initial pressure; and in this case a diflerential gage is unnecessary, as a single gage can be employed and calibrated to indicate directly the flow either in volume or weight.

Fig. 6 shows a meter of the first mentioned class, available for ordinary commercial Where itis desired to maintain the secondary or delivered pressure practically as high as the initial pressure .a single' orifice is sufficient. a supply pipe 40 leading to a unit 12 containing an orifice nozzle 17, this unit coupled to a similar unit 12 which has no orifice nozzle, but is provided with a coupling 41 connecting it witha delivery pipe 42, the regulation of flow being at-a point beyond the illustrated elements. The units 12 and 12 afford two chambers with the orifice 17 between them, there being a The drawing shows f drop in pressure between the chambers in accordance with the rate at which the fluid is drawn from the lower chamber. The tapped boss of the upper chamber has a pipe connection 43 which may be in the form of a" pigtail siphon', and the lower chamber a similar connection 44, the two connections in aceordance'with the differences in pressures in the two chambers. The rate of flow will vary in pro ortion to the square root of the pressure 'fi'erence between the There area number of etficient differential pressure gages on the market available for the described purposes, and therefore the details thereof need not herein be described. The combination-shown in Fig. 6 is useful for many purposes, examples of which are the measuring of discharge of steam from boilers, the deliver of steam to prime movers, the admission of feed water to boilers, the flow of oil in pipe lines, etc.

An instance of the second mentioned class of meters is shown in Fig. 7, in which the supply pipe 40 leads to'a series of three, or more or less, units or chambers '12 arged in .tandem. Orifice nozzles 17 are s own between each two chambers, thus presenting a tandem arrangement permitting conslderable pressure drop between the supply pipe 40 and the delivery pipe 42. A pigtail connection 48 is here taken from the middle chamber, between the orifices, and

leads to cafiiressuregage 49 which may readily be brated to indicate the flow in pounds per hour. This apparatusis adapted to meet certain special but frequently encountered conditions, for example to indicate when and how much steam is being used at some remote point, for example by some low pressure process or apparatus; The control of flow; therefore is beyond the metering apparatus. When no steam is be ing drawn at the low pressure end the gage will give an indication corresponding with boiler pressure. When the distant valve is open there will be flow of steam and a pres: sure drop through each orifice. The age may be selected and calibrated to indicate directly the rate or weight of flow through the s ste n. For example, with one inch or ot er size orifices the pressure in the middle chamber vary accordance with the rate of flow, enabling the dial to be calibrated to hindicatei0 the gate, foirexi? ample, gte num er 0 p0 s o steam p fiour. The first orifice' i n. this combination is important since without the restriction it affords, the steam pressure will continue up to, the second orifice. The first orifice in'efiect is a variable pressure reducer. Where the" initial steam pressure is very high the number of orifices may be. tlbilirge or four in' increased, for example to number, giving a considera reduced delivered pressure and the pressure-reading may be taken mediate chamber.-

.While the described combination of Fig.

7 been discussed only inconnection with .tem according to t om any convenient inter:

the flow of steam the principles can be used for metering 1i uids. In that case if two orifice nozzles o the same size are used, the

ressure in the chamber between them will i e theavera'ge of the initial and final pres; sures. This fact enables'a single gage connection, as shown, to be employed for accurate indication of the rate of flow, assuming either a constant initial pressure or a constant final pressure in the liquid.

The assemblage shown in Fig. 8 ma be used as a fluid metering combination oi the second class, and comprises the threaded supply pipe 52 leading from an pressure regulating means, such as an ori ce system as already described, or a simple throttle.

valve 53, preceded by pipe 54. The pipe '52 leads directly into the orifice unit or chamber 12 containing orifice nozzle-17, and

.the tapped bossa't the side has'a connection 55 in the form of a pigtail siphon to a pressure gage 56. An example of the use .of th-is combination is where steam is to be delivered from a high pressure to a receiving vessel in which the pressure is not in excess of 58% of the initial absolute pressure, this condition'existing in many processes notably in oil refining; If constant flow through the orifice is desired the pressure within the unit or chamber should be uniform, and this may be brought about by replacing the throttle valve 53 by an automatic reducing valve, or if the main line steam pressure is constant the throttle valve may serve, or be replaced by anorifice sysis invention, operating asa pressure "reducing device. With the embodiments of when used for measuring dry steam or other elastic fluid, the age 49 or 56 can be calibrated to show a solute pressure, or about 14.7 lbs. per square inch higher than ordinary er ahead 14.7 spaces on the scale), an then such pressure ga e, and its-pressure graduation marks can e made to indicate directinch, in the case of steam, or 2. correspond- Figs. 7-or 8, or similar flow measuring arrangements,

gage calibrations (e. g. by setting the inting area with another fluid, assumin a pressure drop through the orifice than 58% of the chamber pressure. The

to not less pointer then will indicate not onl theabsolute, pressure, but by the same ca ibrations and readings will indicate the flow rate pounds per hour. When greater flow is'requiredthe orifice area can be a simple mul-p tiple of .0195, e.- g. 1.95, in which case'the j, pressure calibrations of the gage show the rate by using the same simple multiplier, e. g.

100, upon..the pressure indication, and the multiplied readings can be applied to the same calibration marks used for pressure indication. As the pressure in the orifice chamber varies, this variation will be indicated on the gage as a change of absolute pressure, and this change of gage reading atthe same time indicates the change taking place in the rate of steam flow, from which the total flow inany given period of time can be readily figured out. This branch of thepresent invention however is not made the subject of specific claim herein, but is reserved and is made the subject of a copending application for patent.

Pressure reducing apparatuses are indicated in Figs. 9 and 10. The purpose of such combinations is to take down a high initial pressure in easy stages to or below a desi ated maximum pressure. For examp e a boiler pressure of 85 pounds can be reduced so as to deliver not more than 43.13

pounds pressure! The uses are various.

One use is as a supplement to an ordinary or automatic reducing valve, the orifice system located either before or after the valve; for. example the orifice system can be employed to bring down the pressure approximately to the desired reduced pressure, enabling the automatic valve to giv-much more accuracy in control of delivered pressure, although the orifice system can be used without the valve.

Fig. 9 shows a threaded pipe leading to the first of the orifice units 12. Preceding the pipe 60 is shown a blowofi' cock 61, or a safety valve could be substituted, and preceding that a pipe 62 from the steam supply or boiler. Beyond the orifice system is shown a coupling 63 for connecting tothe delivery pipe of the system. Two orifices 17 are shown, one in each orifice unit. In this combination the orifice system, acting as a pressure reducer, may serve to remove certain difiiculties existing in the use of safety valves. When boiler valves are.blown off into atmospheric pressure this causes excessive noise, as well as wear upon the valve, .the-difliculty being so noticeable that special valve seats and'disks have had to be designed in an endeavorto reduce the resulting wear, and the gradual increase of prevailing boiler ressures has accentuated the difliculty. he employment of o e or more orifice units, as indicated in Fig. attached to the outlet of the blowoff valve gives pressure reduction in easy stages so that the steam is eventually ment operates as a mufiier or silencer and discharged at low pressure,

thus avoiding the di culties mentioned. The arrangeprevents injurious vibration. Under the principles as already explained the orifices are readily selected or desi ed to meet any given requirements. Anotfigr advantage in the combination is that the rate of flow through the orifice system, being practically constant for a given boiler pressure, gives a positive check on the amount of steam J,an. 5, 1925.

perheater, to the series of-orificc elements 12 the outlet from which is connected by a coupling 67 with a pipe 68 extending downwardly to a return bend 69, from which extends an uptake 70. This arrangement may afford a seal preventing back flow of vapor. 1

The pipes 68 and 70 are shown broken away, indicating that they may be indefinitely elongated. At the top of uptake 70 is shown a T 71 from which extendsupwardly a pipe 72 to the atmosphere and laterally an elbow 73, with a downtake therefrom to a hot well or elsewhere.

The Fig. 8 combination may be used for direct reading of flow of dry saturated steam per hour, by employing an orifice of approximate area ,01944 sq. in. and shifting the dial pointer upwardly to the extent of 14.? units so as to indicate absolute pressure; whereupon the ordinary *calibration of the dial shows the steam flow in pounds per hour. With a different gas another orifice area will give a similar result. By taking an orifice of an arcaa multiple of that stated, the gage indication will show flow by multiplying' by the same factor. a

The following reservations of rights are indicated. The combination of an orifice system, as that in Fig. 1 'or otherwise, with a relief valve, feed valve, or pump or any other regulator of flow, controlled by the pressure in the orifice system, or changes of such pressure, is not herein claimed but is made the subject of claim in copending ap plications, Serial Nos. 670 and 671, filed The use of such orifice system, per se, as a liquid relief apparatus, without a separate regulator controlled by it, is made the subject of divisional application, Serial No. 302,025, filed August 25, 1928. The embodiments of F igs 6,7 or 8, or analogo s forms, used as flow meters, are not claime herein, but are made the subject of claim in copending application, Serial No. 120,691, filed July. 6, 1926. The use of anorifice system-a'sa mufiler, or a. pressure reducer, as in Figs. 9 or 10, or otherwise, is notherein claimed, but is madefthe subject of claim in copending application Serial No. 119,929, filed July'l, 1926.

It will thus be seen that there has been described an orifice element, a system or assemblage containing the same, and apparallu 'the objects of the present invention. Since many matters of operation, combination, arrangement, structure and detail may be variously modified without departing from the principles involved it is not intended to limit the invention to such matters except so far as specified in the appended claims.

What is claimedis: 1. An orifice element adapted to be interconnected with other elements of fluid flow' predetermined effective area and so arranged that fluid traversing said openings must traverse the orifice, and coupling means at both.

the entrance and exit' openings, one. being exterior and the other interior of the walls of the vessel and complimentary to each other, whereby the element may be coupled to a similar element or other fluid flow apparatus.

2. An orifice element adapted to be interconnected with other elements, of fluid flow apparatus, and consisting of a hollow vessel formin a walled chamber having entrance and cut openings, an orifice nozzle so arranged that fluid traversing said openings must traverse the orifice, and coupling means at both the entrance and exit openings consisting of an interiorly threaded portion at one opening and an exteriorly threaded portion at the other opening, the two corresponding whereby identical elements can be directly coupled in tandem.

3. An orifice element adapted to be interconnected with other elements of fluid flow apparatus, and consisting of a hollow vessel forming a walled chamber having entraiice and ex1t openings, an orifice nozzle so arranged that fluid traversing said openings must traverse the orifice,.and coupling means at both the entrance and exit openings consisting of interior threads at one opening, and a cylindricalportion at the ,other openingwit exterior threads corres nding to said interior threads, and interlor threads for removably receiving and holding said orifice nozzle.

4. An orifice element adapted to be interconnected with other elements of fluid flow apparatus, andconsisting of a hollow vessel forming a walled chamber having entrance and GXIt'OPGIIlIIgS, an orifice nozzle so arranged that fluid traversing said openings.

must traverse the orifice, and coupling means at both the entrance and exit openings, the vessel walls having one or more tapped apertures at a lateral point adapted tobe closed by a plug or connected to other paratus.

'5. An orifice system adapted to be connected with other elements of fluid flow apparatus, comprising a plurality of separate orifice elements coupled together in tandem each orifice element consisting of a hollow vessel forming a walled chamber having entrance and exit openings, and with complementary 'coupllng means at the respective openings, one being exterior and the other interior of the walls of the Vessel, an orifice piece for each vessel so arranged that fluid traversing the system must traverse the orifices, a ressure pipe coupled to the entrance of the rst orifice element, and a discharge pipe coupled to the exit of the last orifice element.

6. An orifice system comprising one or more orifice elements interconnected with other elements of fluid flow-apparatus, and each consisting of a hollow vessel forming a walled chamber having entrance and exit openings, a plurality of orifice nozzles so arranged-that fluid traversing said openings must traverse the orifices in succession and a pressure gageconnected to one of said elements andin communication with the chamber between two orifices. U

In testimony whereof, I have afiixed my signature hereto.

GRANT CAMPBELL.

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