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6.2.5 Oil Resistance Test
Cut three tubes each approximately 150 mm long. Mix equal amounts of oil in which No.
1 lubrication oil of 1-3 types specified in JIS K2215 and the oil specified in JIS K 2209 or
equivalent are blended (See item 7). The mixed oil shall be heated to 50 +/- 3C prior to
testing. Soak the test pieces in the oil mixture for 20 hours. Remove the test pieces from
the oil mixture and lightly wipe the excess oil from the surface. Measure the tensile
strength and elongation of the tube as described in 6.2.4 1.
6.2.6 Flame Resistance Test
Cut a tube approximately 150 mm long. Insert a noncombustible rod into it and bend it
approximately 30 at a point 50mm from one of its ends. Hang it vertically by fixing the
other end so that it can be suspended over a flame of a spirit lamp or gas burner at a
point approximately 20 mm from its bottom end. When the test piece begins to burn
remove it from the flame and record the length of time the piece burns. During the test
provide a windshield to prevent the flame from being blown by a draft or breeze causing it
to flicker.
6.2.7 Heat Characteristic
1. Deformation After Heating
Prepare an arc-shaped test piece 30mm long and measure its thickness. Heat the test
piece to 120 +/- 3C for 30 minutes using a heat deformation tester specified in JIS C
3005 (Testing Methods for Rubber or Plastic Insulated Wires and Cables) item 23. Put
the test piece between the parallel plates of a measuring device shown in Figure 2 and
apply a load of 3.92N (400gf) to the test piece. Condition the assembly at 105 +/- 3C for
30 minutes, remove from heat and cool to room temperature. Remeasure the thickness.
The residual rate shall be calculated using the formula below.
Figure 2
2. Shrinkage After Heating
Cut 3 tubes approximately 300mm long as the test pieces. Put two benchmarks 200mm
apart in center of the test piece. Heat the test pieces to 120 +/- 3°C for one hour, remove
from heat and cool to room temperature. Measure the length between the two marks
using a pair of calipers specified in JIS B 7507 (Venir Calipers) or other measuring
instrument of equal or superior precision. Calculate the decrease rate by the formula
below. The test result shall be represented by an average of the decrease rate of the
three test pieces.
