Tools of the trade

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Whilst fire extinguishers have remained similar in design and operation over the years, there are still quite an assortment of tools and spares needed to carry out competent servicing.

Based on the order of checks in BS5306-3 let’s look at what an extinguisher technician’s toolbox should contain:

  • Cleaning cloths and solution: Prior to carrying out a detailed examination of the exterior of the extinguisher, it should be cleaned off first to help identify corrosion, dents, gouges etc.  Also check that the instructions are legible and include English.
  • Gauge testers: Pressure gauges have to be checked for function and free movement of the needle (a visual check is not enough – the user should already be doing this regularly themselves). Different types of gauge require different tools to use in their test holes;

-          Pump tester: For Mija type gauges and can be used on Wika gauges

-          Needle tester: For Wika type gauges

-          Magnetic tester: For magnetic gauges used by one manufacturer







  • Gauge dots: Pressure gauges have access holes for test equipment, which are sealed with a clear adhesive cover when new. As this has to be removed to use the tester, it needs to be re-sealed in order to prevent contamination. Small adhesive gauge dots should be used for this, usually dated with the year of test and/or colour coded for the year of service.
  •  Weighing equipment: On all extinguishers, regardless of type, the complete mass of the extinguisher should be checked to ensure there isn’t a loss of 10% or more of the contents mass (so a 2kg CO2 total weight should not drop more than 0.2kg from its commissioning total weight, a 6-litre foam should not drop more than 0.6kg, etc).

In addition, cartridge operated extinguishers should have the cartridge removed and weighed using digital scales (battery operated for field use and mains for workshop use) as these are more accurate than a spring balance and can easily be calibrated for continued use.

  • Opening up the extinguisher and removing the hose and horn: Cartridge extinguishers have to be opened annually to weigh the cartridge and inspect the media and interior of the cylinder, so the correct equipment is needed. Also, similar equipment is needed to open up stored pressure extinguishers (other than CO2) for recharging after use or Extended Service. Hoses and horns also have to be removed so they can be blown down to check for obstruction:

-          Strap wrench: Helps steady the extinguisher to exert enough force to loosen the head, normally used for field disassembly

-          Extinguisher clamp/vice: For van or workshop, a fixed clamp is quicker and easier to use

-          Spanners: Adjustable or sized in order to remove hoses and horns

-          Headcap bars: T-bars in a variety of thread types to fit different makes of extinguisher to remove the valve

-          Headcap spanners: C-spanners for specific extinguishers with an external thread and headcap nut

-          Rubber mallet: Whilst not the first tool to grab due to the risk of damage to the valve there will occasionally be the need for a tap or two on stubborn to free headcaps

  • O-rings & fibre washers: Where a hose, horn or headcap/valve has been removed its O-ring or washer should be replaced so a stock of assorted sizes of O-ring for hoses, swivel horns and valves should be held as well as fibre washers for hose and horns.
  • Thread and O-ring lubricant: Before reassembly, threads should usually be lubricated with petroleum jelly being commonly used.
  • Safety pins and tamper seals: The safety pin/clip should be fully removed, and the tamper seal broken, so as to check the operating lever for damage and free movement and that the pin can be easily removed (i.e., It is not bent or rusted). Various spares are required for this:

-          Flag type tamper tags: The most commonly used type of tamper seal, often used in different colours to indicate year of service

-          End cap type tampers: Several brands of extinguishers have a notched pin that can have a cap type tamper fitted (it is not merely a ‘transport’ seal) and some engineers prefer to use these as they are neater and less prone to being accidentally broken

-          Chubb OK pins: The Chubb Euro range (1997-2012) uses a plastic safety pin with integral tamper seal (an OK disc) that is broken in two on removal so the whole unit must be replaced. A competent engineer will have a stock of new pins and discs to replace these with, rather than not remove the pin at all or reuse a broken pin with a flag seal

-          Chubb FX discs: The Chubb FX range (2012-2017) uses a large reusable clip with a separate OK disc which is broken when the clip is removed – again a competent engineer will stock the OK discs

-          Universal OK pin: A thinner version of the Chubb OK pin that fits most standard makes of extinguisher

-          Firechief Pull Safe Pin: An alternative to standard pins this device is easy to grip and remove and won’t jam if the user is accidentally putting pressure on the top level, unlike standard pins.

-          Replacement steel pins: Sometimes an extinguisher has had the pin removed or been lost, so a stock of varied sizes should be held.

  •  Service labels: Essential to record service information (as well as advertise your business).   In addition to adhesive labels on a roll, tie on service tags are important for harsh environments and ADR compliant extinguishers on hazardous goods vehicles.
  • Other labels: A variety of other labels are worth keeping handy:

-          Corrective Action Required labels: Required by BS5306-3 for extinguishers where the required service has not been completed, e.g., an Extended Service

-          Condemned labels: Required for extinguishers deemed obsolete or unsafe for use

-          Discharge horn labels: A handy extra to indicate if a swivel horn is safe to hold or unsafe to hold

-          Low freeze labels: To indicate where an extinguisher is filled with low freeze additive which needs replacing on refilling

-          Verified alternative labels: Required by BS5306-9 where an extinguisher has been filled with a compatible, but not OEM, refill charge

  • Nitrogen regulator and charge adapters: For repressurising extinguishers after refilling, a step-down regulator is needed to safely fill to the correct pressure. A set of recharging adapters are needed to fit the different makes of extinguisher.
  • Refills: A stock of water additive, foam, wet chemical, and powder charges to refill a range of different extinguishers. The OEM charge or a verified equivalent should be used to maintain performance and fire rating.
  • Miscellaneous: Indelible pens for labels/tags, PPE, sterilisation tablets for plain water extinguishers and much more.

Fire Depot has been the UK's favourite fire safety supplier for over 50 years, we know the fire protection and prevention business inside out. Our experienced team can offer advice and guidance about any of our fire safety products. For expert help and advice, please contact the Fire Depot team on 0330 999 2233, email us at visit to see our full range of fire safety products.

The information contained within this blog is provided solely for general informational and educational purposes and is not intended as a substitute for professional advice. Before taking any actions based upon this information, we advise the reader to consult any and all relevant statutory or regulatory guidance and where felt necessary to consult a qualified fire or industry regulation professional. The use or reliance on any information contained herein is solely at the reader’s risk.

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