Foam type fire extinguisher
[we can easily study about foam type fire extinguisher]
Introduction –
Fire extinguisher is a potable first- aid fire fighting equipment that help to extinguish the fire initial stage (short type of fire) to avoid big fire accidents. foam can play big role to extinguish the fire for that invented foam type fire extinguisher it can be also call upgraded version of water type extinguisher, that quickly deal with flammable liquid fire on oil industrial work site.
Definition of foam type fire extinguisher –
This type of extinguisher contains foam solution to extinguish the fire for that call foam extinguisher.
Color –
This type of extinguisher cream color band with red.
This type of foam type extinguisher has 2 types- Chemical foam extinguisher
Mechanical foam extinguisher
Chemical foam type fire extinguisher
This type of extinguisher was using old time but it no available in present for use. It contains chemical solution to make the foam for extinguish the fire for that it call chemical foam extinguisher.
Agents and chemicals –
Extinguishing agents is foam water with. It contain sodium bicarbonate (NaHCO3) and aluminium sulfate [AL2 (SO4)3] to make expelled gas and foam solution.
Reaction -
Sodium bicarbonate (NaHCO3) mix with fresh water to create soda water solution and aluminium sulfate[AL2(SO4)3] mix with soda water solution to create carbon dioxide (co2), aluminium hydro oxide AL(OH)3 and sodium sulfate (Na2SO4) combine produce foam solution that solution contact with air to create foam.
6 NaHO3 +AL2 (SO4)3 = 3 Na2SO4+ 2 AL (OH) 3+6 CO2
Parts of extinguisher -
Extinguisher have 2 sections
Main body
Cap assembly
Main body – steel cylinder, carrying handle, discharge nozzle, foam making branch (FMB), alkaline indicator.
Cap assembly – gun metal cap, T handle, safety pin, sealing cap, inner container,
Function of parts –
• Steel cylinder - it contain soda water solution.
• Gun metal cap – it tightly screws on the cylinder and hold other parts on it.
• T handle – it act like operating liver.
• Safety pin – it lock the T handle from unnecessary charge.
• Sealing cap – it tightly cover on hole of the inner container.
• Inner container – it contain aluminium sulfate AL2 (SO4)3.
• Discharge nozzle- it helps to throw out (6-7kg/cm2) the agents to long (20- 25 feet) distance.
• foam making branch (FMB)– it is a special and important part of the foam extinguisher that help to consume air from outside for mix with solution before exit of agent this process is call venture.
• Alkaline indicator – it help to indicated instant alkaline level.
Assemble of parts –
• It contain 1.6 mm steel cylinder that fill by soda sodium bicarbonate (8%) (NaHCO3) water solution at measurement mark of cylinder capacity.
• Gun metal cap fix on the cylinder.
• T handle attach on cap that easily movement through center of cap.
• Safety pin – attach with T handle.
• Sealing cap fix on hole of inner container that attach with T handle.
• Inner container fix container holder inside of cap fills by aluminium sulfate (12%) AL2 (SO4)3 as per capacity.
• Discharge nozzle fix on cylinder top position.
• Foam making branch (FMB) manually attach just before charge.
• Carrying handle fix on the cylinder.
• Alkaline indicator fix out wall of cylinder beside of cap assembly.
Work technique -
Case of fire first pull up the T handle to remove sealing cap of inner container then aluminium sulfate mix with soda water solution to create expelled co2 gas and foam solution , that contact by air inside of foam making branch to convert solution as foam before throw out.
Operating method -
• First take it to fire site from wall/extinguisher stand.
• Shakes it (3-4 times) for gently mix soda water solution.
• Take proper physically safe position near of fire according of wind direction.
• Remove the safety clip/pin.
• Attach the FMB with nozzle.
• Then pull up the T handle.
• Then it turned upside down for mix to all chemical solution properly.
• Then aim jet foam to fire for extinguish.
Size -
Potable –5 kg, 9 kg.
Mobile - 22 kg, 50 kg, 150 kg.
Mechanical foam fire extinguisher
This type of extinguisher upgrade version of chemical foam extinguisher. It have highly use mainly on oil industrial site in present time. It contains mechanical foam solution to extinguish the fire for that it call mechanical foam type extinguisher.
Chemical, gas and agents-
It contain aqueous film forming foam (AFFF ) chemical solution and protein stabilizer with water act like extinguishing agents. It has co2 gas cartridge for expelled.
Reaction –
Aqueous film forming foam (AFFF) is a foam compound that mix with water create foam solution and the protein stabilizer mix with foam solution that avoid puncher of the foam bubbles due to heat (stabilize the bubbles ) before extinguish.
Parts of extinguisher –
Extinguisher have 2 sections -
Main body and cap assembly
Main body – steel cylinder, siphon tube, strainer, discharge tube, foam Making branch (FMB), carrying handle.
Cap assembly – gun metal cap, plunger/ operating leaver, nick ring, spring pin system, safety pin, vent hole, inner hole, and co2 cartridge.
Function of parts -
• Steel cylinder – it contain foam water solution
Inside of cylinder.
• Siphon tube – it help to pump up the solution to discharge tube.
• Strainer – it help to filter the solution.
• Discharge tube – it help to throw out the agent.
• Foam making branch(FMB)– it is a special and important part of the foam extinguisher that help to consume air from outside for mix with solution before exit of agent this process is call venture.
• Handle – it help to carry and hang on stand of extinguisher.
• Gunmetal cap – it tightly screws on cylinder and hold other parts for that it calls cap assembly.
• Plunger / operating lever – it help to trigger the extinguisher case of fire.
• Nick ring – it help to properly settle of cap on cylinder.
• Spring pin system – it help to puncher to seal of co2 cartridge.
• Cartridge – the inner cartridge contain co2 as capacity.
• Safety pin – it help to lock the plunger /operating lever from unnecessary charge.
• Vent hole – it help to release extra pressure from cylinder.
• Inner hole – it help to spread the co2 inside cylinder after break the seal of cartridge.
Assembly of parts -
• This type of extinguisher contain 1.6 mm steel cylinder that fill by water, Aqueous film forming foam (AFFF) compound(3%-5% according of capacity) & protein stabilizer solution according measurement mark.
• Gunmetal cap fix on cylinder that tightly screw by nick ring.
• Plunger / operating lever attach on cap that easily move through center of cap.
• Spring pin system just fix under the plungers /operating leaver.
• Co2 cartridge hold in side of the cap that screw anti clock wise. (Capacity depends on cylinder size).
• Plunger types have cylinder contains discharge tube on main body but operating leaver types have discharge tube on cap assembly.
• Foam making branch (FMB) attach end position of discharge tube.
• Siphon tube fix from bottom cylinder to connect with discharge tube, and a strainer attach with it inside of cylinder.
• Vent hole present on cap nick and inner hole present inside of cap.
Size -
Potable –5 kg, 9 kg.
Mobile - 22 kg, 50 kg, 150 kg.
Work technique –
Case of fire first hard press on plunger / operating lever to break the seal of co2 cartridge , co2 spread through inner hole to inside of cylinder , co2 create pressure(6-7 kg/cm2) over the solution for that pressurized solution pump up by siphon tube to discharge tube, then FMB consume air from outside to mix with solution for make foam before exit.( Jet foam range 20 – 25 feet)
Operating methods –
• First take it to fire site from wall/extinguisher stand
• Shake the cylinder 3 to 4 times for properly mix all solution before charge.
• Take proper physically safe position near of fire according of wind direction.
• Remove the safety clip/pin.
• Strongly punch on the plunger/operating lever to break the seal of co2 cartridge.
• Hold the discharge tube not to aim direct on the fire , the jet aim to any wall around of fire for that the foam snidely cover the whole fire & extinguish.
Maintains of extinguisher –
Every extinguisher have need proper maintains for it always ready for extinguish fire in emergency.
• This type of extinguisher is one time use by one time refilling.
• Daily/ weekly clean up the whole body
• Check it properly every parts interval every 3 month
• Must be check the weight of co2 cartridge, if it loss of 10% of weight so it not for use.
• All movable parts must be check for to maintain proper movement
• Properly clean up inside of cylinder and check about rust of metal cylinder due to water.
• Check the siphon tube and discharge tube to maintain proper working condition.
• Every 1 year it must be refilling even it not charge.
• Every 4 year it must be hydraulic test by 26 kg/cm2 for 5 minute.
This type of extinguisher refilling easy process
o Open the cylinder and remove used cartridge and fix the new co2 cartridge in holder.
o Fulfil the fresh water, aqueous film forming foam (AFFF) compound (3%-5% according of capacity) & protein stabilizer solution according particular measurements mark of cylinder.
[Foam type fire extinguisher also available as stored pressure type]
Extinguishing method -
foam type fire extinguisher extinguish the fire by 2 method. Smothering and cooling
Smothering – This type of extinguisher use 90% smothering method, foam cover the whole fire to stop flow of o2.
Cooling - This type of extinguisher use 10% cooling method due to water.
Application –
This type of extinguisher specially use for flammable liquid fire/B class fire (diesel, petrol, kerosene). It also use for ordinary fire/a class fire.
Extinguisher Safety-
• Do not place the extinguisher any hot area.
• During use of cartridge type extinguisher be Aware because it can be blast due to fault.
• Extinguisher should be proper maintaining.
• During charge of Foam type fire extinguisher should be tightly hold discharge tube, because it can hit due to pressure.
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