Fire extinguishers are a quiet but critical part of any fire safety setup. You hope you’ll never need one—but if the worst happens, it absolutely must work.
That’s why fire extinguishers don’t last forever.
They have a recommended service life, and in the UK, there are clear guidelines around inspection, servicing, and replacement.
A big part of that has to do with pressure. So, let’s break down why extinguishers have a lifespan, what the pressure inside them really means, and why it’s not worth cutting corners when it comes to replacement.
Do Fire Extinguishers Expire?
They don’t come with a “use by” date like a carton of milk, but fire extinguishers in the UK are time-limited safety devices.
Under BS 5306-3, portable extinguishers must:
- Be visually inspected monthly
- Be serviced annually by a competent person
- Undergo extended servicing or replacement after 5 or 10 years, depending on the type
Even if they look perfectly fine, extinguishers can deteriorate internally or lose pressure, making them unreliable in an emergency.
Why Pressure Matters
Inside every extinguisher is a pressurised container, essentially a mini pressure vessel that’s built to withstand very high internal pressure safely.
Most extinguishers are pressurised to:
- Around 12–15 bar for stored pressure types (like water, foam, or powder)
- Up to 55–60 bar for CO₂ extinguishers, which use liquefied gas under high pressure
What is a “bar”?
One bar is roughly equal to atmospheric pressure at sea level—so 15 bar is 15 times normal air pressure.
To give that some context:
- Car tyre: about 2.2 bar
- Truck tyre: around 8–9 bar
- Fire extinguisher: 12–15 bar (standard)
- CO₂ extinguisher: up to 60 bar
So you’re talking about a lot of pressure inside that metal canister. That’s why:
- The integrity of the cylinder is crucial
- Metal fatigue, corrosion or impact damage can be dangerous
- Extinguishers are strictly regulated under pressure vessel safety standards
Can an Old Fire Extinguisher Be Dangerous?
In a word—yes. While rare, a severely corroded or damaged extinguisher could:
- Fail to discharge when needed
- Leak slowly, losing pressure unnoticed
- In extreme cases, rupture under pressure, posing an injury risk
That’s why the law doesn’t allow for a “wait and see” approach. Extinguishers must be serviced by someone competent—often BAFE or FIA trained—and replaced if found unfit for use.
How Long Does a Fire Extinguisher Last?
In general:
- Water, foam, and powder extinguishers need extended service or replacement every 5 years
- CO₂ extinguishers require hydrostatic testing or replacement after 10 years
Single-use (non-refillable) extinguishers must be replaced at 5 years regardless of appearance.
What’s Checked During Extended Servicing?
Extended servicing includes:
- Full discharge of contents
- Internal inspection for rust, wear or damage
- Valve replacement or refurbishment
- Pressure testing (CO₂ units undergo hydrostatic testing at 250–300 bar)
For comparison, that’s more pressure than most scuba tanks or compressed air cylinders. That’s why the technician handling it must be properly trained and insured.
Why Not Just Leave It?
Besides the safety risks, the Regulatory Reform (Fire Safety) Order 2005 makes it clear: you’re legally required to ensure your fire equipment is:
- Maintained
- Fit for purpose
- Ready to use
Failure to do so could mean:
- Prosecution
- Insurance invalidation
- Real harm to people in the event of a fire
How ESI Can Help
At ESI: Electrical Safety Inspections, we handle extinguisher servicing and supply for clients across Farnborough, Camberley, Reading, Guildford, and the wider Surrey, Hampshire, and Berkshire area.
We:
- Check extinguisher pressure and condition
- Carry out annual and extended servicing
- Advise when replacement is more cost-effective
- Keep detailed records to support your compliance
Don’t risk a pressurised safety device going unchecked. If you’re not sure how old your extinguishers are—or when they were last properly tested—give us a call. We’ll sort it, safely and professionally.
