Designs and materials vary widely among
manufacturers and applications. Rubber, polyolefins, styrenic plastics, SAN,
PVC, ABS, and polycarbonate are all commonly used. Special applications
require flame retardant versions of materials where available. Covers will
sometimes have lead bushing inserts for specific designs.
- Splay, warping/flatness
- Color variations
- Indication of thermal degradation
- Concentricity of vent opening in
- Flame treatment.
Periodic or Vendor Checks:
- Mechanical-impact, flexural
- Chemical-acid resistance, stress