US3667277A

US3667277A - Apparatus for measurement of textile flammability properties

Info

Publication number: US3667277A
Application number: US106115A
Authority: US
Inventors: Bernard Miller; Harold Lambert; Charles H Meiser Jr
Original assignee: TEXTILE RESEARCH INST
Current assignee: TEXTILE RESEARCH INST
Priority date: 1971-01-13
Filing date: 1971-01-13
Publication date: 1972-06-06
Anticipated expiration: 1989-06-06

Abstract

A method and equipment for use in determining the rate of flame propagation and other burning characteristics of sheet materials wherein a test strip of material is supported adjacent its opposite edges and after being ignited is advanced toward the burning zone at a rate sufficient to maintain said zone in a predetermined location. The speed at which the strip of material is moved toward the burning zone is observed and recorded whereby the rate of flame propagation in the material under the test conditions can be determined. The equipment may be housed within an enclosure and the composition, pressure, humidity and other conditions of the atmosphere in which the burning of the material takes place can be varied and controlled so as to obtain consistent and accurate determinations as to the flammability and burning characteristics of the material under any predetermined conditions.

Description

United States Patent Miller et a1.

1 June 6, 1972 [54] APPARATUS FOR MEASUREMENT OF TEXTILE FLAMMABILITY PROPERTIES [72] Inventors: Bernard Miller, Princeton; Harold Lambert, Pennington, both of N.J.; Charles H. Meiser, Jr., Yardley, Pa.

[73] Assignee: Textile Research Institute, Princeton, NJ.

[22] Filed: Jan. 13, 1971 [21] Appl. No; 106,115

Primary Examiner-Richard C. Queisser Assistant Examiner-Herbert Goldstein AttorneySperry and Zoda [57] ABSTRACT A method and equipment for use in determining the rate of flame propagation and other burning characteristics of sheet materials wherein a test strip of material is supported adjacent its opposite edges and after being ignited is advanced toward the burning zone at a rate sufficient to maintain said zone in a predetermined location. The speed at which the strip of material is moved toward the burning zone is observed and recorded whereby the rate of flame propagation in the material under the test conditions can be determined.

The equipment may be housed within an enclosure and the composition, pressure, humidity and other conditions of the atmosphere in which the burning of the material takes place can be varied and controlled so as to obtain consistent and accurate determinations as to the flammability and burning characteristics of the material under any predetermined conditions.

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RECORDER ATTORNEYS APPARATUS FOR MEASUREMENT OF TEXTILE FLAMMABILITY PROPERTIES FIELD OF INVENTION There has been a long continued and urgent demand for the establishment of consistent and reliable tests or standards by which the flammability and burning characteristics of fabrics, films and other sheet materials can be determined. Typical of the problems presented and prior efforts to determine the fire resistance and rate of flame propagation in various sheet materials are described in articles appearing in the Journal of the American Association of Textile Chemists and Colorists at Vol. I, No. 12; (June 4, 1969) and Vol. 2, No. 3 (Feb. ll, 1970). Despite the many attempts to develop such tests and procedures, the equipment heretofore provided and the results obtained in the use thereof have been so imprecise and inconsistent that it has not been possible to establish any generally acceptable and meaningful standards for determining the rate of flame propagation in textiles, films, papers and other types of sheet material.

SUMMARY OF INVENTION In accordance with the present invention burning characteristics of sheet material are observed and evaluated by supporting a strip of the material to be tested at its opposite edges on a drum which is rotatable about a horizontal axis. The strip is ignited at a point near one end thereof and the drum is then rotated to advance the strip toward the burning zone at a speed sufficient to maintain said zone in a predetermined location. The location of the burning zone of the strip may be selected so as to cause the flame to extend either upward over an unburned portion of the strip, or upward away from an unburned portion of the strip or at a chosen angle with respect to the strip. In any event the speed at which the drum must be rotated to maintain the burning zone at the predetermined location and in the selected position with respect to the drum, will indicate the rate of propagation of flame in the material under the test conditions.

The equipment preferably is housed within an enclosure so that the conditions of the atmosphere in which the burning of the material takes place can be controlled to maintain a desired oxygen content, pressure, humidity or the like.

The equipment may further be provided with means for protecting unburned portions of the material from products of combustion or fusion which may fall from the burning zone of the material. I

THE DRAWING FIG. 1 is a side elevation of a typical form of equipment embodying the present invention; and

FIG. 2 is vertical sectional view of the equipment illustrated in FIG. I.

PREFERRED EMBODIMENT OF THE INVENTION In that form of the invention chosen for purposes of illustration in the drawing the equipment embodies a drum 2 mounted for rotation about a horizontal axis 4 and provided with two horizontally spaced spoked wheels or members 6 and 8 through which air and gases may circulate freely. The wheels 6 and 8 have radially extending pins 10 projecting from the periphery thereof to engage the edges of a strip of material 12 to be tested. The strip may be held in engagement with the pins 10 by suitable means such as the flexible retaining bands 14 which extend about the periphery of the wheel and overlie the edges of the strip. The opposite ends of the retaining bands 14 are turned inwardly so as to enter and engage the opposition sides of a retaining notch 16 or the like on the periphery of the wheel. The retaining bands 14 thus hold the strip of material in engagement with the pins 10 and in a position wherein the strip 12 extends transversely of the drum with the central portion of the strip unsupported. The size of the drum may be chosen as desired but in a typical construction the wheels 6 and 8 are 8 inches in diameter and spaced at least 1% inches apart. However, the spacing between the wheels is preferably adjustable to receive strips of any desired width. The strip of material used in carrying out any test may then be from 20 to 25 inches in length and at least 2 inches in width. When thus dimensioned the duration of the burning and testing operation will generally be long enough to assure stabilization of the flame and accurate observation thereof. At the same time the spacing of the wheels 6 and 8 is such that they will not influence or interfere with the propagation of flame in the test material by the removal of heat, confining of the flame, or interference with the circulation of gases into and out of contact with the material. I

The material to be tested may be ignited by any suitable means such as a gas flame projected downwardly from a jet 18 located at a point near the top of the drum 2 and mid-way between the spaced wheels 6 and 8. The flame may be produced and controlled by any suitable means (not shown).

The drum 2 with the strip of material 12 mounted on the periphery thereof may be rotated by any preferred driving mechanism, such as a variable speed motor 20, speed reducer 22, shaft 24 and bevelled gears 26; The speed of rotation of the drum 2 and the rate of linear travel of the material 12 under test are preferably recorded by a tachometer 28 or the like, while the speed of rotation of the drum may be varied as desired by a control device 30.

For most purposes the equipment is housed within an enclosure 32 to which gases, such as a mixture of nitrogen and oxygen, are admitted under control of a pressure regulating valve 34. A gas distributing head 36 and a body of glass beads 38 or the like in the lower portion of the enclosure, serve to assure uniform flow of the gases upward through the enclosure 32 to a vent or outlet 40. If desired a unit 42, such as a calorimeter, gas analyzer, smoke detector or the like may be arranged to receive the gases and products of combustion issuing from the outlet 40. Further, if desired pressure relief means may be incorporated in the unit 42 or elsewhere to permit the atmosphere within the enclosure 32 to be maintained above or below atmospheric pressure or to establish a desired humidity, temperature or other condition in the atmosphere in which the material under test is to be burned.

The enclosure 32 may be formed of glass or other transparent material or may be provided with a sight glass permitting observation of the material under test. If preferred, or in addition to any sight glass provided, a thermocouple or radiation sensing device 44 may be positioned to be actuated by the flame produced by the burning of the material under test. Such a sensing device may be located at any suitable or preferred point about the periphery of the drum 2 and two or more sensors may be provided and positioned at selected points with respect to the test material if desired.

In operating the equipment described, the strip of material 12 to be tested is applied to the wheels 6 and 8 of the drum 2 and held in place on the periphery of the drum by the clamping members 14. One end of the strip is preferably located near the retaining notch 16 in the l l oclock" position near the top of the drum and beneath the gas jet or other ignition device 18. The gas jet is ignited and used to initiate burning of the strip 12 near the leading end thereof and then is removed while the motor 20 is energized to rotate the drum 2 with the test material thereon, say in a clockwise direction as seen in FIG. 1. The drum is rotated at whatever rate necessary to move the flame quickly to the predetermined test position.

When the test point chosen is in the 3 o'clock" position of FIG. 1, for example, the flame from the burning material will extend upward from the burning zone about or over the unburned material surrounding the upper portion of the drum. The motor control device 30 is then actuated to adjust the clockwise speed of rotation of the drum and test material so as to maintain the burning zone of material at the 3 oclock" location and this speed can be maintained as the drum continues to rotate and until the end of the test strip is reached. Adjustment in the speed of rotation of the drum may be controlled manually if desired. However, by locating the thermocouple 44 or other flame sensing means above the "3 o'clock" position or in some other suitable position to respond to the presence of a flame in the 3 oclock" position the speed of rotation of the driving motor 20 may be automatically confound to be about revolution per minute-allowing nearly 2 minutes for observation of the burning strip being evaluated. Such prolonged and detailed study and observation of the burning characteristics of materials has not been possible heretofore and renders it possible to attain the high degree of accuracy and consistency in test results to establish uniform standards as to the flammability of materials.

While the operation of the equipment as described above presumes that thebuming zone will be maintained in the 3 o'clock" position wherein the flame from the burning material extends upward over the advancing unburned portion of the test strip, it is also of practical interest to conduct tests and evaluation of materials when the burning zone is at 12 oclock, 9 oclock, or any location in between. For some purposes and for a complete evaluation of the burning characteristics of materials it may be desirable to run successive tests on strips of the same material with the burning zone held in several different positions about the drum.

The equipment of the present invention may be used in determining the burning characteristics of practically any type of sheet material including textile materials formed from any of the naturally'occurring and man-made fibers such as cotton, wool, silk, nylon, polyester and the like, as well as mixtures or blends of such fibers. Plastic films, paper, felts, floor coverings, rubber sheeting, and laminated materials as well as the properties of metal foils, screen, and wall board or flexible plywood may be evaluated in the same way by means of the present invention.

In testing sheet material formed of fibers or plastic compositions which may fuse or melt or develop sparks or charred products which tend to drip or fall from the burning zone onto unburned portions of the material on the lower part of the drum, it is generally desirable to provide the drum with a wire mesh screen or-the like which is located within the drum as shown at 50. Such a screen or shield should be spaced from the periphery of the drum and the test material a sufficient distance to avoid any interference or adverse influence on the burning characteristics of the material and the free flow of gases into and out of contact therewith.

in order to obtain a more extended evaluation of the buming characteristics of materials, the gases introduced into the enclosure to maintain the desired atmosphere adjacent the material being tested may be varied in composition, pressure and other properties. For most purposes it is desired to introduce a mixture of nitrogen and oxygen into the enclosure 32. The percent of oxygen can be varied over an extended range and it has been found in general that there is a linear relationship between the burning rate and the volume fraction of the oxygen. The slope of the relationship representing the sensitivity of the burning rate to oxygen appears to increase as the fabric weight decreases. Other significant relationships can also be determined, as for example, the fact that fabrics containing a mixture of fibers such as 50/50 polyester and cotton, exhibit quite different burning characteristics when the cotton yarns extend in the direction of the flame rather than transverse to the flame-the latter being substantially less sensitiveto the oxygen content of the atmosphere in which buming takes place.

in a like manner the pressure of the atmosphere in which the tests are carried out may be at, above, or below atmospheric pressure. The humidity may be controlled or varied and other properties of the atmosphere within the enclosure 32 may be selected to obtain an extended and varied series of data on the burning properties of sheet material. Moreover, analysis of the products of combustion and determinations with respect to the heat developed in burning materials under varying conditions can be obtained in the practice of the present invention. It should therefore be understood that the particular construction and methods of utilizing the .equipment of the present invention as shown in the drawing and described above, are intended to be illustrative only and are not intended to limit the scope of the invention.

We claim:

1. Equipment for determining a burning characteristic of sheet material comprising a rotatable drum, means for supporting the sheet material to be evaluated on the periphery of said drum, means for igniting said sheet material, means for rotating said drum with the ignited material thereon about a horizontal axis, means for varying the speed of rotation of said drum to maintain the ignited portion of the sheet material in a predetermined location, and means for determining the speed of rotation of said drum.

2. Equipment as defined in claim 1 wherein said drum includes parallel members between which the material to be evaluated is suspended.

3. Equipment as defined in claim 1 wherein said drum and material are enclosed within a housing and means are provided for controlling the atmosphere within the housing.

4. Equipment as defined in claim 3 wherein said drum and material are enclosed within a housing and means are provided for controlling the oxygen content of the atmosphere within the housing.

5. Equipment as defined in claim 3 wherein said drum and material are enclosed within a housing and means for controlling the pressure of the atmosphere within the housing.

6. Equipment as defined in claim 1 wherein temperature sensing means are positioned to respond to the temperature of flame produced on burning of the material.

7. Equipment as defined in claim 1 wherein a thermocouple is positioned adjacent said predetermined location.

8. Equipment as defined in claim 1 wherein the means for determining the speed of rotation of said drum includes a recording device.

9. Equipment as defined in claim 1 wherein means are provided for protecting the material being evaluated from the ignited material and products resulting from ignition thereof.

10. Equipment as defined in claim 1 wherein a screen is mounted within the drum and positioned to catch molten material and products falling from the ignited sheet material.

11. Equipment as defined in claim 1 wherein said drum embodies two similar spaced parallel members having circular peripheral edges and means on said edges for holding sheet material in a position extending transversely between said members.

12. Equipment for determining a burningcharacteristic of sheet material comprising two horizontally spaced supports engagable with opposite edges of a sheet of material to be evaluated, means located adjacent said sheet for initiating burning of said sheet material, means for maintaining a burning zone of said sheet material in a predetermined location in eluding means for advancing an unignited portion of said material toward said burning zone so as to maintain the buming zone of the material in said location, and means for determining the rate at which said material is advanced toward said location.

13. The method of determining a burning characteristic of sheet material which comprises the steps of holding an elongated strip of the material suspended between parallel supports, initiating burning of said strip at a point spaced from one end of the strip, moving the strip toward the portion of the strip which is burning at a speed which will serve to keep the content of the atmosphere within said enclosure is maintained substantially constant.

17. The method as defined in claim 15 wherein the pressure of the atmosphere within said enclosure is maintained substantially constant at a value above atmospheric pressure.

18. The method as defined in claim 15 wherein the position of the unburned portion of said strip of material with respect to the burning portion of the material is maintained substantially constant.

Claims

12. Equipment for determining a burning characteristic of sheet material comprising two horizontally spaced supports engagable with opposite edges of a sheet of material to be evaluated, means located adjacent said sheet for initiating burning of said sheet material, means for maintaining a burning zone of said sheet material in a predetermined location including means for advancing an unignited portion of said material toward said burning zone so as to maintain the burning zone of the material in said location, and means for determining the rate at which said material is advanced toward said location.

13. The method of determining a burning characteristic of sheet material which comprises the steps of holding an elongated strip of the material suspended between parallel supports, initiating burning of said strip at a point spaced from one end of the strip, moving the strip toward the portion of the strip which is burning at a speed which will serve to keep the burning portion of said strip in a predetermined location, and determining the speed at which said strip is moved toward the burning portion thereof.

14. The method as defined in claim 13 wherein the supports for said material are rotated about a horizontal axis while the material is burning.

15. The method as defined in claim 13 wherein the material and its supports are located within an enclosure and a condition of the atmosphere within said enclosure is maintained substantially constant while said material is burning.

16. The method as defined in claim 15 wherein the oxygen content of the atmosphere within said enclosure is maintained substantially constant.