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50 Gasket Tests
Section 50 effective April 13, 1993
50.1 The requirements in this section apply to a gasket that is required for protection against dust and
other contaminants entering an enclosure described in Section 7, Enclosures Used for Protected
Environments.
50.2 Neoprene or rubber compounds and solid polyvinyl-chloride material, except foamed materials, shall
have physical properties as indicated in Table 50.1 before and after the conditioning indicated in Table
50.2.
50.3 Foamed neoprene or rubber compounds shall not harden or otherwise deteriorate to a degree that
affects their sealing properties after conditioning as specified in Table 50.2.
50.4 A thermoplastic gasket shall not deform or melt, or otherwise deteriorate to a degree that will affect
its sealing properties after the conditioning indicated in Table 50.2.
50.5 Gaskets of materials other than those specified in 50.2 – 50.4 shall be non-absorptive and shall
provide equivalent resistance to property changes.
Table 50.1
Physical properties for gaskets
Physical property
a
Neoprene or rubber compound Polyvinyl-chloride materials
Before
conditioning
After conditioning Before conditioning After conditioning
Tensile set - maximum set when 1
inch (25.4 mm) gauge marks are
stretched to 2- 1/2 inches (63.5
mm), held for 2 minutes and
measured 2 minutes after release
1/4 inch (6.4 mm) – Not specified Not specified
Elongation – minimum increase in
distance between 1 inch gauge
marks at break
250 percent [3-1/2
inches (88.9 mm)]
65 percent of
original
250 percent [3-1/2
inches (88.9 mm)]
75 percent of original
Tensile strength – minimum force at
breaking point
850 psi (5.86 MPa) 75 percent of
original
1200 psi (8.27 MPa) 90 percent of original
a
To be determined using the test methods and apparatus described in Standard Test Methods for Rubber Properties in
Tension, ASTM D412-80, except the method for tensile set is to be as specified in this table.
OCTOBER 15, 2004 UL 458 69
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