The UL 242 Standard is maintained by Underwriters Laboratories (UL) and focuses on equipment designed to provide pressure and vacuum relief for tanks containing flammable and combustible liquids. 1. Scope of the Standard UL 242 covers several types of venting devices, including:
The investigation revealed that the non-UL 242 thermostat had developed a film of corrosion on its bimetal disc after just 14 months in a humid basement. That film created electrical resistance, which generated heat, which fooled the thermostat into thinking the water was hotter than it was. The heater never shut off. ul 242
The result was a slow, invisible disaster. Moisture would creep into the thermostat housing. Inside, it would corrode contacts, bridge terminals, and eventually cause one of two failures: The UL 242 Standard is maintained by Underwriters
Vents must be shown to open and close consistently without sticking, even after long periods of inactivity or exposure to debris. Importance in Industrial Safety Moisture would creep into the thermostat housing