The Basics – what we do

#What is a portable extinguisher?

A hand-held (or wheeled) container of extinguishing agent (water, foam, powder, CO₂, wet chemical or clean agent), with a means of pushing it out under pressure. It's for tackling a fire in its early stages, by someone trained, while it's still small.

#The types and how to recognise them

#In the UK BS

Since BS EN 3, UK extinguishers have red bodies with a coloured band or panel (BS 7863) to show the agent:

Specialist: Class D powder (often blue, labelled for metal fires, e.g. L2 or M28 powders) and lithium-ion battery extinguishers.

#In the US NFPA

US extinguishers are normally all red with no colour code. You identify them by the label, which shows:

• the agent (e.g. "ABC dry chemical", "Purple K", "CO₂"),
• the UL rating, e.g. 4-A:80-B:C (the numbers show how big a fire it's rated for; the "C" just means it's safe on electrical),
• pictograms for each class.

#Anatomy of an extinguisher

#Two ways of making the pressure

• Stored pressure: the body is permanently pressurised (usually with nitrogen or dry air). It has a gauge. This is the most common type.
• Cartridge-operated: a small gas cartridge pierces when operated and pressurises the body at that moment. There is no gauge on the body. These are common in wheeled units, harsh industrial environments and some powder units.
• CO₂ is a special case: the CO₂ is its own pressure source (about 55–60 bar at room temperature). There's no gauge, so it's checked by weighing.

#The jobs you'll do

#Monthly inspection: step by step

flowchart TD
  A["Go to extinguisher location"] --> B{"Is it there and<br/>easy to get to?"}
  B -- No --> X["Report: missing or obstructed"]
  B -- Yes --> C{"Pin in and<br/>tamper seal intact?"}
  C -- No --> Y["Report: may have been used"]
  C -- Yes --> D{"Gauge in the green?<br/>(stored pressure only)"}
  D -- No --> Z["Report: needs service"]
  D -- Yes --> E{"Any visible damage, corrosion,<br/>leaks or blocked nozzle?"}
  E -- Yes --> Z
  E -- No --> F{"Instructions legible<br/>and facing out?"}
  F -- No --> W["Turn round / report label"]
  F -- Yes --> G["✔ Record: date + initials"]
  W --> G

#Annual service: step by step

This is the core job. The general routine below applies to both BS and NFPA. The Whys & the Standards page covers the details and differences.

flowchart TD
  S["Start: at the extinguisher<br/>with spare replacement available"] --> A["Identify: type, serial, manufacture date,<br/>last service, last discharge/hydro test"]
  A --> B{"Is a deeper test due?<br/>(discharge / 6-year / hydro / overhaul)"}
  B -- Yes --> B1["Swap with spare & take to workshop<br/>or replace – see 'What's due' chart"]
  B -- No --> C["External check: body, dents,<br/>corrosion, label legible"]
  C --> D["Check pin, seal, lever, handle"]
  D --> E{"Stored pressure?"}
  E -- Yes --> E1["Check gauge in green<br/>and gauge not stuck"]
  E -- "No – cartridge" --> E2["Open: check powder free-flowing,<br/>weigh cartridge, check seals & vent"]
  E -- "No – CO₂" --> E3["Check horn & hose<br/>(non-conductive horn)"]
  E1 --> F["Weigh & compare with<br/>label/last recorded weight"]
  E2 --> F
  E3 --> F
  F --> G["Check hose, nozzle/horn:<br/>cracks, blockage, perishing"]
  G --> H["Check bracket/stand, signage,<br/>right type for the risk?"]
  H --> I{"Everything OK?"}
  I -- Yes --> J["Fit new tamper seal<br/>Update label/tag<br/>Record on service report"]
  I -- No --> K{"Can it be fixed on site?"}
  K -- Yes --> K1["Repair/recharge, then re-check"] --> J
  K -- No --> L["Replace with spare<br/>Label as defective or condemned<br/>Report to client"]

#Key takeaways

• UK = colour band, US = read the label.
• Stored pressure has a gauge. Cartridge and CO₂ don't. CO₂ is checked by weighing.
• Monthly = look; annual = service; every few years = deeper test.
• Always leave a spare in place of any extinguisher you take away.