Is it Safe to Use an LPG Cylinder that's Exposed to Fire?
Occasionally people experience a BBQ fire as the result of a faulty cylinder, regulator or hose.
This is one reason why you should always leak test your BBQ connection after replacing gas bottles.
However, fires can happen and the gas bottle may be exposed to the flames.
There may also be other circumstances where the bottle is subjected to fire, such as a building or bush fire.
If this happens, is it safe to keep using the gas bottle (propane tank)?
Possible Hidden Damage
The flames and heat can cause hidden damage, especially to the gas bottle valve. Damage to the BBQ regulator might also be hidden.
There are components within the valve that could perish as a result of the heat.
The plastic dust cap on the Pressure Relief Valve (PRV) could melt and flow back into the valve, causing it to malfunction.
A blocked PRV could contribute to an explosion in an overpressure situation.
The soft rubber or plastic seals within the valve could fail, causing leaks or preventing gas from flowing.
The spring in the pressure relief valve could be weakened by heat, causing it to release gas unexpectedly at pressures below the pressure release specification.
The rubber O-ring from the regulator could melt into the orifice of the valve preventing it from closing and/or opening.
The rubber O-ring could also melt and get onto the threads, preventing the regulator from making a gas-tight connection.
Fire Effects on Regulators
LPG (propane) gas regulators reduce the LPG pressure delivered to the gas appliances from the gas bottles.
Regulators also have components within them that can be adversely affected by heat.
Regulators have a diaphragm, which is a flexible rubber disc that responds to pressure changes and functions to regulate the flow of gas to the proper pressure.
This rubber disc could melt, causing the regulator to malfunction.
The diaphragm works in combination with springs and other parts within the regulator.
These springs could also be weakened by heat.
The regulator vent, which allows the diaphragm to move freely, could become obstructed by molten material, preventing the diaphragm from operating properly.
A damaged regulator could prevent the flow of gas.
Worse still, it could allow gas to flow at too high a pressure, resulting in a serious safety hazard
Condemnation of the Gas Bottle or Propane Tank
Fire damaged cylinders are condemned - removed from service permanently - when identified during re-inspection.
During a gas cylinder inspection, the external surface of the gas bottle is inspected for defects, as defined by the applicable Standard, AS 2337.1-2004.
The Standards can vary by country but most are very similar.
The kind of things they look for are swelling of the cylinder walls, the depth and diameter of any dents, the length and depth of any gouges, the depth and intensity of any corrosion, the presence of any cracks, or any damage from fire or heat.
Failure in any one category will see the cylinder condemned.
The gas bottle in the picture was condemned for fire damage.
If the heat intensity is great enough to affect the paint then there could easily be other hidden damage, as previously discussed.
Safety should always come first.
Preventing BBQ fires, in the first instance, should constantly be the goal.
Always do a BBQ leak test every time you change BBQ gas bottles.
However, if a gas bottle or propane tank is exposed to fire, the best course of action is to replace it.
The same applies to regulators and hoses.
In addition, always discard the gas bottle in a safe manner.
Comments, questions or feedback?
The information in this article is derived from various sources and is believed to be correct at the time of publication. However, the information may not be error free and may not be applicable in all circumstances.