Page 4 SPECIFICATION RT-218 ISSUE 4
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4.3.6 Heat Resistance
Three specimens prepared and measured in accordance with 4.3.2 shall be conditioned for 168 hours in a 225
± 3°C (437 ± 5°F) oven. After conditioning. the specimens shall be removed from the oven, cooled to 23 ±
3°C ( 73 ± 5°F) and tested for tensile and elongation in accordance with 4.3.2.
4.3.7 Dielectric Strength
The dielectric strength of the tubing shall be measured under oil in accordance with ASTM D 149. Five 6-
inch (1S0-mm) specimens of tubing shall be recovered over a metal mandrel by conditioning for 3 minutes in
a 200 + 3°C (392 ± 5°F) oven. The mandrel diameter shall be slightly larger than the fully re covered inside
diameter of the tubing being tested. The metal mandrel shall serve as one electrode, and a 1-inch (25-mm)
wide strip of lead foil wrapped around the outside of the tubing as the other electrode. The test voltage shall
be applied at a rate of rise of 500 volts per second. Thickness measurements for calculating dielectric
strength shall be made at the point of breakdown.
4.3.8 Corrosive Effect
The tubing shall be tested for copper mirror corrosion in accordance with ASTM D 2671, Method A. using
the time and temperature specified in Table III. For tubing sizes 1/8 and larger, specimens shall consist of
1/8 x l-inch (3x 2S-mm) strips cut longitudinally. Evidence of corrosion shall be the removal of copper from
a mirror, leaving an area of transparency greater than 5 percent of its total area.
4.3.9 Flammability
Flammability shall be tested by the following methods.
4.3.9.1 UL Subject 224, VW-1
Five 26-inch (660-mm) specimens shall be tested in accordance with UL Subject 224, VW-I.
4.3.9.2 ASTM D 876
Five 22-inch (660-mm) specimens shall be tested in accordance with ASTM D 876
4.3.10 Vacuum Outgassing
Three 0.5 ± .05 gram specimens shall be recovered for 3 minutes at 200°C and then tested for percent total
weight loss and percent volatile condensable materials. The conditions for testing are: exposure time, 24
hours; sample temperature 130 ± 3°C; condensing surface temperature, 18 ± 3°C; and pressure, not greater
than 1 x 10
5
torr. The vacuum shall be provided by a diffusion pump, liquid nitrogen trap vacuum system.
The apparatus shall consist of a glass sample chamber, refluxing liquid heat source and a polished stainless
steel plate in close contact with a copper cold finger cooled internally by circulating water. The axis of the
exit of the sample chamber shall be perpendicular to and approximately 15-mm from the cooled condensing
plate. A Cahn RG micro balance or equivalent shall be used for weighing. The specimen shall be weighed
before and after conditioning and total weight loss calculated and the condensing plate shall be weighed
before and after to calculate percent volatile condensable material.
