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testing

Gasoline Test

Test Purpose:

Todetermine the effect of gasoline on the switch bodies of membrane switches construct-ed with a Bergquist HeatSeal spacer and with a pressure sensitive acrylic spacer.
SETUP RESULTS Standard 3 x 4 matrixswitches 2.6” x 3.0” with 3” tails are used for testing. All switches are constructed one month prior to any testing. Spacers tested are as follows:1) Bergquist HeatSeal spacer- .008” total thickness (.005” base polyester with .0015” of HeatSeal adhesive on each side).2) Pressure sensitive acrylicspacer - .009” total thickness (.005” base polyester with .002” of pressure sensitive acrylic adhe- sive on each side).Pre-testing of switches isperformed as in the General Purpose Cleaners Test. HeatSeal spacer - After 14days of immersion in gasoline there were no visual signs of degradation. There were no meas- urable changes, throughout the 14-day duration of the test, in the insulation resistance measure- ments.Pressure sensitive acrylicspacer - Severe dissolving of the PSAadhesive and ingression of the gasoline occurred within the first 2 hours of the test. After 2 hours the parts had failed the insu- lation resistance test. After four- teen days switches were com- pletely delaminated with only some gelatinous masses of PSA adhesive left.
FIGURE 16: PSA switch soaked in gasoline and green dye for 10 hours indicates substantial fluidingression and switch delamination. 8