MEC&F Expert Engineers : FIRE TRIANGLE (FHO) AND EXPLOSION PENTAGON (FHO+CS)

Monday, April 6, 2015

FIRE TRIANGLE (FHO) AND EXPLOSION PENTAGON (FHO+CS)





There are three necessary elements which must occur simultaneously to cause a fire: fuel, heat, and oxygen (FHO).  These elements form the three (3) parts of the fire triangle.  By removing any one of these parts, a fire becomes impossible.  


For example, if there were very little or no oxygen present, a fire could not occur regardless of the quantities of fuel and heat that were present. Likewise, if insufficient heat were available, no concentrations of fuel and oxygen could result in a fire.

On the other hand, for an explosion to occur, there are five (5) necessary elements which must occur simultaneously: fuel, heat, oxygen, suspension, and confinement (FHO + CS or FHOCS).  These form the five parts of the explosion pentagon.  Like the fire triangle, removing any one of these parts would prevent an explosion from occurring.  


For example, if fuel, heat, oxygen, and confinement occurred together in proper quantities, an explosion would still not be possible without the suspension of the fuel.  A fire could still occur, though, as the fuel, heat and oxygen elements are there.  If the burning fuel were then placed in suspension by a sudden blast of air, and there was still confinement present, then all five parts of the explosion pentagon would be satisfied and an explosion would be imminent.

Remembering the three sides of the fire triangle (fuel, heat, oxygen) and the five sides of the explosion pentagon (fuel, heat, oxygen, suspension, confinement) is important in preventing fires and explosions at any facility. By eliminating the possibility of either suspension or confinement, an explosion cannot occur, but a fire may occur. By eliminating the fuel, the heat, or the oxygen requirements, neither a fire nor an explosion can occur.