Fuel gas interruption: How to operate the furnace draft fans for long-term and short-term situations
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For gas-only heating furnaces, in the event of a fuel gas supply interruption, how should the blowers of the furnace be operated for long-term and short-term situations?
When stopping the fuel gas supply, for safety reasons, fire-suppression steam is usually supplied directly to the furnace; it can be kept active for a short period of time. The frequency of the forced draft fan can be reduced； If the period is long, natural ventilation can be used instead. In fact, when the fuel gas supply is stopped, as long as steam is supplied to the furnace, the other factors aren’t that important; in my opinion, it’s sufficient to maintain normal furnace pressure.
If the fuel gas supply to our plant is interrupted, the main burner and the pilot light will trigger an interlock mechanism due to low fuel gas pressure, causing the blower and exhaust fan to shut down as a protective measure
The blower should be stopped when the furnace is turned off
When turning off the heating furnace, first check whether the pilot light is burning properly. If the burning is normal, simply close the gas manual valve ； If the perpetual light goes out, the fuel must be shut off; ignition can be resumed only after the fire suppression steam system has been inspected and found to be in order