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Fire tube boilers can be equipped with explosion relief doors. These doors function like a pressure relief valve calibrated to a very low pressure (approximately 30 inches water column) and protect the boiler against major damages caused by combustion gas explosions.

The explosion relief doors should be installed between the second and third passes of the combustion gas and should have a peripheral relief design, thus guaranteeing their effective operation.  Although they are often not given the importance they warrant, explosion relief doors are a vital safety component of the boiler.

When are the Explosion Relief Doors Activated?

The primary job of these doors is to mitigate explosions within the boiler furnace.

Explosions may occur when the fuel valve (solenoid) fails to seal, allowing fuel to pass towards the boiler furnace.  This may happen at the time of closing if a piece of material other than the fuel (a chip of wood, cork, stone, tow, dirt, sand, etc) gets between the seat of the valve; or when, because of some malfunction, the seal of the solenoid valve seat ceases to be air tight.

Another type of explosion can occur because of liquid or gas fuel residues in the boiler furnace which can result due to a crack in the nozzle.

When the boiler does not have explosion relief doors, or when the doors are installed at the exit of the third or fourth pass, the shock wave of the explosion will cause damage.  Normally, the back lid of the boiler will come off, pushing through walls with the consequences of such an event being potentially fatal.

Additionally, the pressure vessel of the boiler will have to absorb periodic large-scale stresses caused by explosions that exceed the design parameter, which sooner or later will cause fractures in the furnace and/or tube sheets.

All Calderas Powermaster horizontal boilers come equipped with properly installed explosion relief doors that provide for the safe and reliable operation of your boiler.