Electric process heaters that interface with flammable materials in explosive environments need to be properly evaluated to protect the equipment against catastrophic failures. There are several possible protection methods that may be employed to protect from a potential explosion. A temperature class requirement will be provided by the user based on the explosive gases that may be present in the installation area. The maximum surface temperature of the process heater must then be evaluated to assure compliance.
Temperature classes that are based on the maximum operating temperature for heaters prescribe the level of safeguards. Determining the temperature class for a specific electric process heater is unique compared to other electrical components installed in classified locations. The temperature code, or T-code, is highly dependent on the process conditions of the heating application. Global Temperature Classes/Codes are broken down into the following various levels.