UL 2255-2021 pdf download – Receptacle Closures.
9 Mold Stress Relief Test 9.1 A receptacle closure shall not show signs of twisting, distortion or other deformation that would affect its ability to be used with a receptacle after being conditioned as described in this Section. Exception: A receptacle closure made ofthermosetting material is not required to be subjected to this test. 9.2 Nine receptacle closures are to be placed in a circulating air oven maintained at a temperature of 70 °C (158 °F) for 7 hours. The devices are to be removed from the oven and allowed to cool to room temperature before determining compliance. 10 Blade Strength Test 10.1 General 10.1.1 The blades of a receptacle closure shall withstand the application of the test forces described in 10.2, 10.3 and 10.4 without cracking or breakage. Permanent deflection of the closure blade or face upon completion of the testing meets the intent of this requirement. 10.2 Vertical blade orientation 10.2.1 Six receptacle closures are to be subjected to this test. Three closures are to be tested as received and three tested after being subjected to the Mold Stress Relief Test, Section 9. Each closure in turn is to be supported with its face fixed in a horizontal plane and its blades projecting downward in a vertical orientation as shown in Figure 10.1. A weight that exerts a force of 20 lbf (89 N) is to be suspended from each blade in succession. The pull is to be gradually applied and held for one minute.
10.3 Horizontal blade orientation, flat of blade 10.3.1 Six receptacle closures are to be subjected to this test. Three closures are to be tested as received and three tested after being subjected to the Mold Stress Relief Test, Section 9. Each closure in turn is to be supported with its face fixed in a vertical plane and its blades projecting horizontally with the flat surface of the blade parallel to the ground as shown in Figure 10.1. A force of 20 lbf (89 N) is to be exerted on the flat surface of each blade in succession, within 3/16 inch (1.9 mm) of the tip of the blade. The force is to be gradually applied and held for one minute. 10.4 Horizontal blade orientation, edge of blade 10.4.1 Six receptacle closures are to be subjected to this test. Three closures are to be tested as received and three tested after being subjected to the Mold Stress Relief Test, Section 9. Each closure in turn is to be supported with its face fixed in a vertical plane and its blades projecting horizontally with the edge of the blade parallel to the ground as shown in Figure 10.1. A force of 20 lbf (89 N) is to be exerted on the edge of each blade in succession, within 3/16 inch (1.9 mm) of the tip of the blade. The force is to be gradually applied and held for one minute.