FED-STD-791D
6.2 Test specimen preparation
6.2.1 Test specimens are to be cut using ASTM die A or equivalent.
6.2.2 Straight specimens may be prepared where it is not practical to cut ASTM
dumbbell specimens. The minimum length must be 10.2 cm (4 in). The width should be 1.27
cm (1/2 in) between the jaws which are 2.54 cm (1 in) apart.
6.3 Test procedure
6.3.1 Volume swell, change in hardness and change in tensile strength are all determined
relative to original properties, from the post-test condition of the same specimens. The original
tensile strength and hardness shall be determined, using duplicate specimens cut from the same
sheet from which the test specimens were obtained. The duplicate specimens should be cut from
an area of the sheet which is immediately adjacent to the area from which the test specimens
were cut. The original rubber specimen volume is determined from the test specimen prior to
immersion in the oil sample.
6.4 Preparation
6.4.1 Clean all glassware.
6.4.1.1 Rinse in solvent, rinse with acetone and air dry.
6.4.1.2 Soak in glass cleaning solution for 2 h (minimum).
6.4.1.3 Rinse thoroughly with tap water, and then with distilled water.
6.4.1.4 Dry in oven at 100C (212F) and store in dust-free location.
6.4.2 Preheat and adjust oven to maintain a temperature of 121 1C (250 2F).
6.4.3 Prepare standard test silicone rubber specimens.
6.4.3.1 Do not buff.
6.4.3.2 Cut three pieces (per 6.2) from the sheet. Pieces must be cut with the grain of the
rubber as indicated by two grain marks at the top of the slab.
6.4.3.3 Punch a 0.3175-cm (1/8-in) diameter hole at the center of the 10.16-cm (4-in)
side, about 1.905 cm (3/4 in) from the top edge.
6.4.3.4 Mark each piece for identification by cutting small pieces from one or more
corners.
6.4.3.5 Attach the wire suspension device to each piece.
162
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business