Interpretation ID: nht87-2.27

TYPE: INTERPRETATION-NHTSA

DATE: 06/29/87

FROM: JONATHAN JACKSON -- COMMERCIAL TESTING CO

TO: DOUG COLE -- NATIONAL VAN CONVERSION ASSOCIATION, INC.

TITLE: NONE

ATTACHMT: ATTACHED TO LETTER DATED 11/01/88 FROM ERIKA Z JONES TO DOUG COLE; REDBOOK A32, STANDARD 302; LETTER DATED 06/22/87 FROM ROSE M TALISMAN TO DOUG COLE; LETTER DATED 06/08/87 FROM ROSE TALISMAN TO DOUG COLE; LETTER DATED 06/23/87 FROM DOUG COLE T O STEVE KRANTZICE

TEXT: Dear Sir:

When we receive a request for the MVSS 302 test, we use the methodology printed in the Federal Register, Vol. 36, No. 5 - January 8, 1971. It is entitled Motor Vehicle Safety Standard No. 302. The test apparatus is a commercially available Horizonta l Burning Cabinet which we purchased from Custom Scientific Instruments. The burner is fueled with natural gas.

Recently, we did a test for you on a fabric. You questioned the use or non-use of wire supports on this type sample. Paragraph S5.1.3 of the Standard states that a "...specimen that softens and bends at the flaming end so as to cause erratic burning ..." may be supported with wires. The fabric that we tested for you does not fall into that category. It is supported by the tension of the U-frame and does not distort when it burns. The use of wire supports on this type material may give mis-leading results as the wires act as a heat sink.

Our further interpretation of the Standard (paragraph S5.3 (a)), is that a material which is intended for use in a size less than can be supported by the U-frame, the use of wire supports is acceptable. Further reference is made of paragraph S5.2.1 w hich states that the "...maximum available length or width of a specimen is used where either dimension is less than 14 inches or 4 inches respectively."

Our interpretation of the Standard as noted above does not allow use of wire supports on this type material unless the fabric were intended for use in maximum widths of 4 inches.

If you have any questions, please call me.

ENCLOSURE

Sincerely,

FEDERAL REGISTER VOL 36 NO 5, JANUARY 8, 1971 [OMITTED]

MOTOR VEHICLE SAFETY STANDARD NO. 302 FLAMMABILITY OF INTERIOR MATERIALS

PASSENGER CARS, MULTIPURPOSE PASSENGER VEHICLES, TRUCKS, AND BUSES

TEST METHOD

MATERIAL DEVELOPMENT & TESTING LABORATORY

FISHER BODY DIVISION

GENERAL MOTORS CORPORATION

FLAMMABILITY OF INTERIOR TRIM MATERIALS

I. GENERAL DESCRIPTION

THIS PROCEDURE IS USED TO DETERMINE THE BURNING RATES OF MATERIALS USED IN THE OCCUPANT COMPARTMENTS OF AUTOMOBILES.

II. EQUIPMENT AND/OR MATERIAL REQUIRED

A. THE TEST IS CONDUCTED IN A METAL CABINET TO PROTECT THE TEST SPECIMENS FROM DRAFTS. THE INTERIOR OF THE METAL CABINET IS 381 MM LONG, 203 MM DEEP AND 355 MM HIGH. IT HAS A GLASS OBSERVATION WINDOW IN THE FRONT AND A CLOSABLE OPENING TO PERMIT IN SERTION OF THE ALUMINUM[Illegible Word] SPECIMEN HOLDER. FOR VENTILATION, IT HAS A 13 MM CLEARANCE SPACE AROUND THE TOP OF THE CABINET, TEN 19 MM DIAMETER HOLES IN THE BASE OF THE CABINET AND LEGS TO ELEVATE THE BOTTOM OF THE CABINET BY 10 MM.

1. THE TEST SPECIMEN IS INSERTED BETWEEN TWO MATCHING U-SHAPED FRAMES OF ALUMINUM STOCK 25 MM WIDE AND 10 MM HIGH. THE INTERIOR DIMENSION OF THE U-SHAPED FRAMES ARE 51 MM WIDE BY 330 MM LONG. ALL SPECIMENS ARE KEPT HORIZONTAL WITH HEAT RESISTANT .2 5 MM CHROMEL WIRE SPANNING THE WIDTH OF THE U-SHAPED FRAME UNDER THE SPECIMEN AT 25 MM INTERVALS.

2. AN ALUMINUM STAND IS USED TO SUPPORT THE U-SHAPED FRAME WHICH LOCATES THE TEST SPECIMEN IN THE CENTER OF THE CABINET.

3. A BUNSEN BURNER WITH A TUBE OF 10 MM INSIDE DIAMETER IS USED. THE GAS ADJUSTING VALVE IS SET TO PROVIDE A FLAME WITH THE TUBE VERTICAL OF 38 MM IN HEIGHT. THE AIR INLET TO THE BURNER IS CLOSED.

NOTE: SEE FISHER DRAWING NO. EQ 199 FOR DETAILS REGARDING ALL ABOVE EQUIPMENT.

B. A CONTROLLED TEMPERATURE AND HUMIDITY CHAMBER OR EQUIVALENT.

C. CLICKER DIE 100 MM X 355 MM FOR CUTTING TEST SPECIMENS.

FLAMABILITY TEST VARIABLES THAT AFFECT THE BURN RATE WHEN PERFORMING FISHER BODY TM 32-12

1. ALWAYS CLEAN THE U-SHAPED FRAMES BEFORE STARTING EACH BURN TEST (RESIDUE OILS, CARBON, ETC., FORM ON THE U-SHAPED FRAME AFTER EACH TEST)

2. MAKE SURE THE .25 MM CHROMEL WIRES ARE PERFECTLY STRAIGHT (HORIZONTAL). SAGGING WIRES WOULD ALLOW CERTAIN TEST SPECIMENS TO SAG.

3. MAKE SURE THE DOOR ALWAYS FITS FLUSH TO THE TEST CABINET. (FROM TIME TO TIME, HEAT CAUSES THE DOOR NOT TO FIT SMUGLY CAUSING OR ALLOWING A DRAFT).

4. ALWAYS EXCHANGE THE AIR INSIDE THE TEST CABINET WITH FRESH AIR. (AFTER EACH TEST SMOKE WILL STAY INSIDE THE CABINET UNLESS BLOWN OUT). FISHER BODY USES AN AIR JET TO EXCHANGE AIR.

5. KEEP THE FLAMMABILITY TEST CABINET AS NEAR ROOM TEMPERATURE AS POSSIBLE BEFORE STARTING EACH TEST. (SPARE CABINET LIDS, SPARE U-SHAPED FRAMES COMPRESSED AIR ARE USEFUL OPTIONAL ITEMS).

6. LEAD FLAME (FLAME THAT FLASHES FORWARD OF THE MAIN BURNING AREA) USUALLY OCCURS ON VINYL COATED FABRICS AND MUST BE OBSERVED VERY CAREFULLY BY THE OPERATOR.

7. CORRELATION DIFFICULTY - IF PERFORMING DUPLICATE TESTS, ALWAYS CUT SPECIMENS IN THE SAME AREA CONSIDERING THICKNESS, WIDTH, RIBS IF PLASTIC PARTS, ETC.

8. FLAT BLACK INTERIOR CABINET FINISH - A SHINY INTERIOR TENDS TO RADIATE (REFLECT) HEAT INSIDE THE CABINET; ALSO, CAUSES A CLEANING PROBLEM AFTER EACH TEST.

9. VENTILATION HOLES - KEEP OPEN. BURNING MATERIALS AND BLOWN MATERIALS WILL COVER THESE HOLES AND WILL PREVENT AIR CIRCULATION WITHIN THE CABINET.

10. SPECIMEN IDENTIFICATION - BE CAREFUL WHEN MARKING SPECIMENS FOR IDENTIFICATION SINCE ENAMELS, INKS, ETC, COULD AFFECT YOUR TEST RESULTS.

THE SPECIMEN IS PRODUCED BY CUTTING THE MATERIAL IN THE DIRECTION THAT PROVIDED THE MOST ADVERSE TEST RESULTS. THE SPECIMEN IS ORIENTED SO THAT THE SURFACE CLOSEST TO THE OCCUPANT COMPARTMENT AIR SPACE FACES DOWNWARD ON THE FRAME.

MATERIAL WITH A NAPPED OR TUFTED SURFACE IS PLACED ON A FLAT SURFACE AND COMBED TWICE AGAINST THE NAP WITH A COMB HAVING SEVEN TO EIGHT SMOOTH ROUNDED TEETH PER 25 MM.

PRIOR TO TESTING, EACH SPECIMEN IS CONDITIONED FOR 24 HOURS AT A TEMPERATURE OF 21 DEGREES C + 1.5 DEGREES C AND A RELATIVE HUMIDITY OF -0.0

50% + 0.0. TO FACILITATE HANDLING, SEVERAL PIECES MAY BE TAKEN - 5%

FROM THE HUMIDITY CHAMBER AND PLACED IN A POLYETHYLENE BAG TO RETAIN MOISTURE UNTIL THEY ARE TO BE BURNED.

V. TEST PROCEDURE

A. MOUNT THE SPECIMEN SO THAT BOTH SIDES AND ONE END ARE HELD BY THE U-SHAPED FRAME AND ONE END IS EVEN WITH THE OPEN END OF THE FRAME. WHERE THE MAXIMUM AVAILABLE WIDTH OF A SPECIMEN CANNOT BE HELD IN THE U-SHAPED FRAME, PLACE THE SPECIMEN IN POSIT ION ON WIRE SUPPORTS AS DESCRIBED IN 11A.1., WITH ONE END HELD BY THE CLOSED END OF THE U-SHAPED FRAME. SPECIMENS SHORTER THAN 355 MM MAY BE POSITIONED ON THE WIRE SUPPORTS AND ALIGNED WITH THE OPEN END OF THE FRAME FOR IGNITION PURPOSES.

B. PLACE THE MOUNTED SPECIMEN IN A HORIZONTAL POSITION IN THE CENTER OF THE CABINET.

C. WITH THE FLAME ADJUSTED ACCORDING TO II A.3, POSITION THE BUNSEN BURNER AND SPECIMEN SO THAT THE CENTER OF THE BURNER TIP IS 19 MM BELOW THE CENTER OF THE BOTTOM EDGE OF THE OPEN END OF THE SPECIMEN.

D. EXPOSE THE SPECIMEN TO THE FLAME FOR 15 SECONDS.

E. BEGIN TIMING (WITHOUT REFERENCE TO THE PERIOD OF APPLICATION OF THE BURNER FLAME) WHEN THE FLAME FROM THE BURNING SPECIMEN REACHES A POINT 38 MM FROM THE OPEN END OF THE SPECIMEN.

F. MEASURE THE TIME THAT IT TAKES THE FLAME TO PROGRESS TO A POINT 38 MM FROM THE CLAMPED END OF THE SPECIMEN. IF THE FLAME DOES NOT REACH THE SPECIFIED END POINT, TIME ITS PROGRESS TO THE POINT WHERE FLAMING STOPS.