US2636388A

US2636388A - Flammability tester

Info

Publication number: US2636388A
Application number: US93217A
Authority: US
Inventors: James R Blegen
Original assignee: OF PLASTICS INDUSTRY Inc S
Current assignee: OF PLASTICS INDUSTRY Inc S; SOCIETY OF PLASTICS INDUSTRY Inc
Priority date: 1949-05-14
Filing date: 1949-05-14
Publication date: 1953-04-28
Anticipated expiration: 1970-04-28

Description

April 5 J. R. BLEGEN 2,636,388

FLAMMABILITY TESTER Filed May 14, 1949 4 Sheets-Sheet 1 I N VEN TOR.

BY V

HTTORNEY April 28, 1953 J. R. BLEGEN FLAMMABILITY TESTER Filed ma 14, 1949 .uulll' l INVENTOR. .lZzmas E fi/ggm/ BY April 28, 1953 J. R. BLEGEN FLAMMABILITY' TESTER 4 Sheets-Sheet 3 Filed May 14, 1949 INVENTOR.

- .jama if filggen flaw/11 MM 19 TTOIPNE Y J. R. BLEGEN FLAMMABILITY TESTER April 28, 1953 4 Sheets-Sheet 4 Filed May 14, 1949 INVENTOR. 12:14:: E 31 g BY Patented Apr. 28, 1953 FLAMMABILITY TESTER James R. Blegen, Pottstown, Pa., assignor to The Society of the Plastics Industry, Inc., a corporation of New York Application May 14, 1949, Serial No. 93,217

Claims. (01. 73-432) This invention relates to an apparatus for testing the flammability characteristics of combustible sheeted material such as plastic films, fabrics and the like, and more particularly comprises an apparatus for automatically testing the ease of ignition and rate of burning of such sheeted material.

This invention comprises a box-like cabinet having an ignition member such as a predetermined pointed flame located inside. A guideway set at a diagonal angle is directed toward the fiame which is positioned near the bottom of the guideway. A switch is also located at the lower end of the guideway which is operated by the weight of the loaded sample holding rack, so that as soon as the rack is slid into place where the flame can strike the sample, the first timing operation is initiated.

I find it very advantageous to hold each sample in a rack which is readily removable. A number of these sample holding racks can be provided and samples can be mounted and threaded up in advance. It is an important feature of my invention that these racks are capable of holding the sample firmly in place without the necessity of using supporting wires. I have found that supporting wires tend to transmit heat from the burning sample and give false results. To accomplish this result the removable rack is lJ-shaped with the open end insertable first so that a free edge of the sample is accessible to the ignition flame. 7 V The holding rack is made with an upper and lower'member and the sample is clamped between these two. The upper holdingmember has projecting edge portions which slide on the guideway in the cabinet and the sample to be tested is held pressed against the under surface of the upper part of the holding rack. This means that the upper surface of the material to be treated is always in the plane of the upper surface of the guideway irrespective of the thickness of the material under test. As a result, the spacing from the ignition flame to the test sample is always the same.

Each sample holding rack carries spaced-apart flat springs tensioned outwardly to operate timing mechanism located on the guideway. When the sample is assembled on the holding rack these springs are held in retracted position by spaced threads which cross the upper surface of thetest sample. The threads (ordinarily of cotton) are'readily ignited andare so positioned;

2 and thereby initiate a'timing operation. The second thread is spaced a predetermined distance from the first and when-the second thread is burned, its spring likewise is released to control a second timing operation.

In the preferred form, the holding rack has its bottom portion so shaped that a segment of the test film will be substantially vertical in the cabinet-whereas the main portion of the film will be in a slanting position. By providing this bottom vertical segment of the test film and by positioning one of the control threads near the top of this segment, s'u'ch thread will be burned by the first flash of flame resulting from the ignition of the test sample. This operates mechanism which will measure the elapsed time between the operation of the switch controlled by the insertion of the rack, and the time when the fiash burns the first thread.

It is also contemplated that the burning of the first thread will initiate a second timing operation which will be terminated by the burning of the second thread. The elapsed time between these two will measure the burning rate of the main body portion of the sample.

The actual angle of the slanting portion of the test film is not critical. Ordinarily a slope of 45 is preferred but an angle of from 25 to relative to the base of the cabinet is operable. Furthermore. while I prefer to use two threads to measure the ease of ignition and rate of burning, the greater number may be used if desired.

Ordinarily the timing mechanism will consist of electrically operated clocks but mechanically operated clocks may be employed if desired.

The two members ofthe holding rack may be clamped together in any desired fashion or if the samples to be tested are of more or less uniform thickness they can be hinged together at the upper end and clamped atthe lower end.

While I prefer to ignite the test sample with a flame I may, under some circumstances, get valuable results using an electrical igniter such as a hot wire.

In order to get a further type of measurement from my structure, I find it advisable to provide means for measuring the temperature of the fiame resulting from the test sample. This may be in the form of any well-known temperature measuring device located above the guideway but preferably a needle thermocouple is employed connected to a pyrometer. g 'In some cases the samples to be tested will not support combustion. In such case, they must be placed in a flame. For this purpose I provide a second flame, the size of which can be carefully controlled for purpose of standardization and arrange to have the sample positioned in this flame. In such case automatic timing ordinarily is not feasible and therefore I prefer to supply additional controls for the timing mechanism so that the timing mechanism can be manually operated, as by push buttons.

The cabinet may beprovided with vent holes for exit of waste gases, at the top of the side panels. An inlet vent for fresh air may be provided at the bottom of one side panel. The test flame is preferably a butane gas flame of a predetermined size and it is directed at a predetermined and fixed angle ontothe film surface. Other gases than butane are operable, for example propane, pentane, water gas. etc..but..butane is preferred. A manometer may be pro vided to measure the gas pressure of the fuel flame.

Also while my appa-ratus may be used for measuring the. ease of ignition-end rateof burning in aconsecutive manner, it mayalso be used for. individually. determining either the ease of ignition or rate of burningof-the test; sample.

My. invention-may be readilyv understood. from the example illustrated in :the accompanying drawing, in which Fig. 1 is "a-sideview-of the invention broken away inpart to'show the assembled sample holding rack in its operable position avithin the cabinet.

Fig. 2 is a'top'v-iewrshowing the electrical clock arrangement.

Fig. 3 front View broken away and showing a sectional view of the rack in operable position. Fig. 4 is a viewtalren along line4--.- l:of Fig. 3

and shows the assembled sample holding rack.

Fig. 5 is a view takenal'onglineS-S of Fig. .4

and-shows in detail themethod of supporting the test film.

Fig. 6 is a view takenfialo'ng line ii--6*of Fig.4 and shows in operablerelation-a threaded tensioned spring adjacent to an electrical switch.

Fig. 7 is a detail view 'of' the-front'electrical switch broken awayinparttoshow theoperating lever.

Fig. 8 is a rear viewof' the view shown in Fig. 7, and

Fig. 9 is a schematic wiring diagram indicating the mannerof operating the electrical clocks.

In these drawings I have illustrated one embodiment of my invention and have sliown'thesame assembled with the sample-holdingrack in operable position. I

A cabinet Zllf has afirst'electrical'clockfl, a second electrical clock 22,an-electiicalswitch 23, and a glass door 24 for viewing "the manner of combustion of the film. It also has a'manometer 25 open to the atmosphere and connected to the gas fuel line at 25.

A sample-holding rack '21 having a top U- shaped element'tlil and-a bottom U-shaped'element 29, is adapted to slide on awg'uideway with the lower face'of element 28 resting on the upper surface of guideway iiil, which. latter is'set at an angle of about to the horizontal by means of short supporting pillars 3 band tall supporting pillars '32. The rack is introducedinto the cabinet through side opening 33 andslides into operable positionat the bottom of the guideway. The combustion gas is introduced through conduit 34 and conducted to.- aneedlenozzle "or jet '35 supported -in. a. movable ball 7 36 in .ball block 31.

The top U-shaped element 28 carries on leg 28a lower flat spring 38 and upper flat spring 39, each having a thread holding notch 40 near its movable end. These springs are fixed to blocks ii and the limit of travel of the springs may be arrested by stops 42. The leg 28 has also two C-shaped slots 53 to allow for slipping thethreads M to the underside of the legs of the U-shaped element 23 andinto grooves 45 across the face of film 45. Threads M are led to the upper side of the leg 28b of element 28 and secured to bindingposts 47. An insulated handle 58 is attached to element 28. A flat spring 59 in conjunction with spring 56 secures the film 46 between the top U-shaped element 23 and the bottom U- shaped element 29, each element having 3, turned- :down-segment 5! located at the forward end of their respective prongs. These turned-down segmentsfil are preferably at an angle of about 45 so that the film held by them will be approximately vertical when the rack is positioned in the cabinet.

.A lower front. microswitch -52 attached-.- to. the front runway of guidewayfiil hasaleverdii located over push button M. .The leverfislisactuatediby the lower front leading edge 55:0f the top U- shaped element 28. A lower rear microswitchbii and an upper rear microswitch-E'l are attached to the rear runway ofguideway 36. -Microswitch 55 has a push buttontt actuated .by spring *38 whereas microswitch 5'! has a. push button 559 actuated by spring '39.

In operating my invention I attach -cotton threads 51 through the slots 49sof springs 38 and 39 and conduct the threadsito the lower Sidfi'fOf U-shaped top element 28 byslippingxthe threads through the'C-shaped-.slot 43. .Therthreads are then pulled across the open spacebetweenthe two legs or" this elementand led into the grooves d5 of the leg 28b and finally pulled-tight and afiixed to bindin posts 41- so that the-

springs

38 and 39 will not contact microswitch'push buttons 58 and 59 when the'rack 21 is slid into place on guideway 30. The threadconnected to spring 38 is designated as' ida andthethread connected to spring 3%? as Mb. A shell of combustible'material 45 (such for example as aplastic' filml is placed in between the top U-shaped element 23 and bottom U-shaped element 29 and is held in fixed position by spring clamps' l and '50.

After the sample holding rack "21 is assembled, it is inserted into cabinet 20 through opening 33' and slides downonguideway 38. When itreaches the bottom of the slide the sample-enters the flame directed from nozzle 35'and at the same time lever 53 is tripped to operate push button 54 of switch Eithereby starting electrical clock 2|. The sample (if of combustiblermaterial) will immediately ignite andthe first flash of flame will burn thread 44a. This willrelease spring 38 which will operate buttoniil and switch 56, simultaneously stopping clock :2I and .starting clock 22. It is important that the devicebe so constructed that thread 4411 will-notbe-burned bythe ignition flamebut will be burned by the first burst of flame from theignitionof thetest sample, in order that the first clock-may record the ignition or flash time.

After the initial flash the film burns until thread Mb attached to spring39 is ignited whereupon this spring Will operate button.59 of microswitch 51 to stop clock 22. The .time.- interval recorded on'clock 22 records the time of-combustionof the .film from thelflrst flashmntil combustion has reached the point where the second thread 44b is burned.

In order to measure the heat of the combus- On some occasions it is desired to test the combustion rate of a material which will not itself support combustion. This demands that the material be kept in a flame. For this purpose I supply a burner 64 which can be carefully, ad-

justed to give a standard flame size. This is connected with a pipe 66. which in turn is connected to a source of gas. The sample may be hung at any convenient point within the casing as for example from the hooks 68 (See Fig. 1).

For measuring this type of combustion, manual control is advisable and accordingly I supply a push button 10 for manually operating .clock 2|, a center post switch 12 for changing the circuit from automatic to manual operation and push button 14 for operating clock 22. The operator can by some practice standardize-on the degree of combustion to be measured in any given sample.

The electrical connections are indicated in'Fig. 9, in which 16 are the usual prongs for attaching an electrical extension cord, 18 is a transformer and 80 is a pilot light. For automatic operation,

center post switch 12 is left in the position shown in Fig. 9 and switch 56 is also initially in the position shown in Fig. 9. Switch 23 is open, switch 5! is closed and both push button switches 10 and 14 are closed. When switch 52 is closed a circuit will be closed through clock 2| starting it in operation. When switch 56 is operated to its other position, the circuit through clock 2| is broken and the circuit closed through clock 22. When switch 51 is operated, this circuit is broken.

For manual operation switch 56 is left in the position shown in Fig. 9 but switch 12 is moved to its other position (its upper position in the figure) and switch 51 is left closed. Switches 10 and 14 are manually opened and toggle switch 23 closed. Clock 2| can be operated by manually closing switch 10 and clock 22 can be operated by closing switch 14. For test purposes, with switch 12 in its upper position and switches 10 and 14 closed, the toggle switch 23 can be used to be sure that both clocks are operating correctly.

With this device we can test a vast number of types of materials and can measure the relative infiammability of them. Thus we have made comparisons between such materials as paper, rubber, various types of plastics including thin gauge unsupported films, heavy-gauge unsupported films, supported films and rigid sheeting and textile fabrics of all sorts. For example, we have tested broadcloth, medium-weight rayon fabric, rayon chiffon, rayon marquisette, cotton marquisette, corduroy, glazed chintz, single and double-coated rubber fabric, unsupported rubber film, oil-coated cloth, pyroxylin-coated fabric, ethyl cellulose rigid sheeting, vinyl acetate rigid sheeting, unsupported thin and heavy gauge vinyl sheeting, supported vinyl sheeting, poly-- ethylene and chlorinated polyethylene films, paper and cellophane and have found the tester to perform very satisfactorily.

In addition to measuring the rate of ignition and rate of intensity of combustion we have found that the removability of the film holder permits us to withdraw the holder as soon as the second thread has been burned and test the sample for difficulty of extinguishmentby block ing out the fire under standardized conditions. It is understood that the example given in the specification is intended only by way of illustration and that it may be modified in many details without departing from the spirit of my invention.

What I claim is:

1. An apparatus for determining the flammability characteristics of sheeted material comprising a pair of U-shaped members for holdin a sheet to be tested while stretched across the legs of the apparatus with the central portion and one edge of the sheeted material unsupported, means for igniting the sheet at the unsupported edge, means for holding combustible threads across the face of the sheet at predetermined intervals and means controlled by the successive combustion of such threads for measuring the time interval between their combustion.

2. An apparatus as specified in claim 1 which further includes means for holding said members in a sloping position.

3. An apparatus as specified in claim 1, in which the sheet to be tested is held against an under face of the upper one of said pair of U- shaped members and said U-shaped members are supported by the under face of such upper member so that the upper face of the sheeted material is at a predetermined level relative to such support.

4. An apparatus as specified in claim 1 which includes means for measuring th intensity of the heat generated.

5. In an apparatus for determining the flammability characteristics of sheeted material, the combination of a pair of time clocks, means for holding a sample to be tested, a flame for initiat ing combustion of such sample, means for simultaneously starting one clock and exposing the sample to the flame, automatic means for stopping such clock and starting the second clock when the sample is ignited and burned a predetermined distance and means for stopping the second clock when the sample has burned a second predetermined distance.

6. In a device of the type described, a cabinet, means movable within said cabinet for holding a sample of material with a portion arranged substantially vertical, means adapted to ignite a lower part of said vertical portion of such sample when said holding means is moved into operative position relative to the igniting means, a timing mechanism, means for starting said timing mechanism .when the sample holding means is moved into operative posit on relative to the igniting means, a separate inflammable member positioned adjacent an upper partof the said vertical portion-of such sample in position to be ignited by the burning of such sample and said timing mechanism being controlled by the burning of such inflammable member so that when said vertical portion of the sample is ignited at a lower point, a measurement may be taken of the time elapsed before said inflammable member is ignited by a flame from the sample.

7. A combination as specified in claim 6 in which the means for holding the sample comprises a frame and the cabinet is provided with guideways within which'said frame is adapted to slide to bring a sample within the frame into operative position relative to the igniting means and which further includes means adapted to be operated by the sliding of'said'frame to initiate the operation of said timing mechanism-as: the

includes a second inflammable member located:

adjacent 'a portionof such sample snaced lat erally from the first inflammable'member'and which also includes a second timing mechanism and means responsive to the burning of said first inflammable member tor simultaneously stopping theffi'rsttimingmechanism and starting the secondtimingjmechanism, said second timing mechanism. being controlled by the burning. of'such second inflammable "member to measure the elapsed'time io'r'flaineftofmdve laterally from. the'first. inflammable m'emher'to the second in flammable member. I

9. A structure'as'specified 'in claim 6. which the means for holding a. sample. of material can.

prises 1a U-shapedframe andthe means for ig niting a sample held in such frame is adapted to ignite the sample at the open end of the U.

10. A structure as specified in-claim 6 in. which said infiammable'member consists of an inflammable thread holding a spring under tension so v Narne Date Hubert Dec. 18,1945

FOREIGN PATENTS Country Number Number Date 80,275 1 Austria Mar. 10,1920