Fire extinguisher service; how it is done

Fire extinguisher service is needful to ensure that fire extinguishers installed in our organization are in a workable state; however, the NFPA (National Fire Prevention Association) requires inspection of your extinguisher every month. Also as part of the annual maintenance, it is required by I.S. 291:2015 that at least one third of all water, foam, dry powder and carbon dioxide extinguishers will be test discharged and refilled annually.

A fire extinguisher, is an active fire protection device used to extinguish or control small fires, often in emergency situations. It is not intended for use on an out-of-control fire, such as one which has reached the ceiling, endangers the user.

Fire extinguisher service is best done by a trained and qualified engineer. It is advised that an expert be hired to get this done regularly. However, a member of staff could equally be trained to do this in order to safe cost for the organization.

How to carry out fire extinguisher service

Servicing a fire extinguisher is done depending on mode of operation of the fire extinguisher, i.e, stored pressure of cartridge operated.

Stored pressure fire extinguishers consist of a cylinder containing the extinguishing agent (water, powder, foam etc.) and are permanently pressurized with either dry air or oxygen-free nitrogen while cartridge operated extinguisher are made up out of a cylinder filled with the extinguishant (water, foam, powder etc) and a gas cartridge containing highly pressurized CO2. The cylinder itself is not pressurized while not in use and the pressure is only released from the cartridge once the handle is squeezed and pierces the cartridge.

I will list out the procedure for fire extinguisher service base on their mode of operation.

N/B: The list is not on a sequential order.

 

Stored pressure fire extinguisher (Mode of fire extinguisher service)

  1. Visually inspect the fire extinguisher for corrosion and damage.
  2. Check that the extinguisher has not been used, by checking that safety pin and tamper seal are in place.
  3. Check that the operating instructions on the extinguisher are clear and legible.
  4. Remove the discharge hose and check for blockages and corrosion, if the discharge hose has been removed, replace the “O” ring.
  5. Remove the headcap of the extinguisher (slowly in case there is any pressure in the cylinder from a leaking cartridge)
  6. In the case of powder extinguisher, visually inspect the contents to ensure that it shows no signs of caking or clumping. If there is any evidence of caking then try to agitate the content. If it is not successful, dispose of the contents and replace with new
  7. In the case of water based extinguishers, pour the contents into a calibrated bucket and inspect the inside of the cylinder with a torch, looking for any sign of corrosion or bubbling in the lining. Measure the contents using the bucket, if there is more than a 10% discrepancy then replace and investigate.
  8. Weigh the extinguisher ensuring that it meets the weight recorded on the service label (Investigation and recharge is required if a weight loss exceeds 10%).
  9. Wipe down the extinguisher exterior with a cloth.
  10. Fill in the details required on the service label (date, weight, engineer initials and next service date).
  11. Verify the pressure gauge indicator is in the green zone of the gauge. Verify that the gauge is in working order by carrying out a gauge test with a pump gauge tester or pin test. (This step is not applicable for CO2 fire extinguishers)
  12. Break the tamper seal by withdrawing the safety pin/clip. In the case of a metal pin; check that it is in good condition. Refit/replace the safety pin/clip and then secure in place with a tamper seal.
  13. Visually inspect the fire extinguisher body for external corrosion or damage that could impair the safe operation of the extinguisher, in particular check the head cap. If this is made from plastic, check for UV degradation.

 

Cartridge pressure fire extinguisher (Mode of fire extinguisher service)

  1. Visually inspect the fire extinguisher for corrosion and damage.
  2. Check that the extinguisher has not been used, by checking that safety pin and tamper seal are in place.
  3. Check that the operating instructions on the extinguisher are clear and legible.
  4. Remove the discharge hose and check for blockages and corrosion. If the discharge hose has been removed, replace the “O” ring.
  5. Visually inspect the fire extinguisher body for external corrosion or damage that could impair the safe operation of the extinguisher, in particular check the head cap. If this is made from plastic, check for UV degradation.
  6. Ensure that the manufacturer’s extinguisher labelling is in good condition, legible and printed in English.
  7. Weigh the extinguisher ensuring that it meets the weight recorded on the service label (Investigation and recharge is required if a weight loss exceeds 10%).
  8. Unscrew the head cap assembly to not more than one third of extent necessary for full disengagement – this allows any pressure remaining in the extinguisher to escape through the automatic means of venting. Then continue to open the extinguisher slowly.
  9. Remove the extinguisher head cap away from the extinguisher body.
  10. Examine the head cap and operating mechanism for damage.
  11. Examine the gas cartridge and if safe to do so, remove the cartridge from the head cap. Visually inspect the gas cartridge for corrosion or damage – in either case replace the cartridge in accordance with manufacturer’s instructions.
  12. Check if the gas cartridge is more than 10 years old – otherwise replace it.
  13. Check weigh the mass of the gas cartridge against that marked on the gas cartridge body. Although a tolerance of -10% (15% for cartridges with contents less than 30 grams) is allowed it is good practice to replace it if it has lost weight.
  14. Check that the firing pin is in place and operates correctly.
  15. Check that the discharge hose, hose nozzle, dip tube and strainer are free from obstructions and damage. Pass air through the discharge hose, dip tube and strainer,   checking for blockages and correct operation.
  16. Examine the pressure release slots in the head cap threads – clean as necessary.
  17. Fit a new head cap ‘O’ ring.
  18. Assemble the head cap, discharge hose, dip tube and gas cartridge together and put to one side so that the extinguisher body and contents can be dealt with.
  19. Refit the head cap and tighten down firmly.
  20. Weigh the extinguisher total mass.
  21. Wipe down the extinguisher exterior with a cloth.
  22. Fill in the details required on the service label (date, weight, engineer initials and next service date).

 

See videos

Part 1 Fire extinguisher service (Check here)

Part 2 Fire extinguisher service (Check here)

 

 

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