Posted on: 4 April 2016
At a glance, fire extinguishers are pretty much identical in form and function, and while different extinguishing agents have different uses, they're all operated in largely the same way. However, one hidden factor can drastically affect the efficiency of an extinguisher, and its suitability for your needs -- the method in which it is powered.
Most fire extinguishers available on today's market are known as stored pressure extinguishers, but you can also find extinguishers powered by gas cartridges. Each type of extinguisher propellant has its own particular strengths and weaknesses, so it's important to know which propellant type is most suited to your needs.
Why should I choose stored pressure extinguishers?
Stored pressure extinguishers hold their extinguishing agents inside the main body of the extinguisher, where they are pressurised with the addition of compressed gases (air for foam extinguishers, nitrogen for dry powder extinguishers, etc.). As such, the extinguishing materials are expelled automatically when the hand operated valve of the extinguisher is opened.
The popularity of stored pressure extinguishers is no accident, as this method of extinguishing agent propulsion holds a number of advantages over gas cartridge propulsion:
- Simplicity -- Because a stored pressure extinguisher is constantly pressurised, it requires very few moving parts to function, only requiring a valve to regulate flow. By contrast, gas cartridge extinguishers require separate mechanisms to mix their pressured gases with their extinguishing agents. As such, stored pressure extinguishers are generally simple to use and are less to encounter mechanical malfunctions.
- Size and weight -- Stored pressure extinguishers are generally lighter and less bulky than gas cartridge extinguishers due to their single-cylinder design, making them easier to use for long periods or in tight spaces.
- Versatility -- Some specialised extinguishing agents such as carbon dioxide and vaporising liquids are incompatible with gas cartridge extinguishers, while stored pressure extinguishers can carry any agent currently in widespread use.
- Maintenance -- Simple construction means that stored pressure extinguishers generally need less maintenance. Most stored pressure models also come with a pressure readout fitted to the handle or top cap of the extinguisher, allowing you to easily check whether an extinguisher has lost pressure. Gas cartridge models must generally be weight to detect gas leakage.
Why should I choose gas cartridge fire extinguishers?
Gas cartridge fire extinguishers are larger and more robustly-built than their stored pressure brethren, and use two separate chambers. One contains the extinguishing agent, while the other is the eponymous gas cartridge and contains an appropriate compressed gas. When operated, the seal separating the two chambers is broken, allowing them to mix and forcing the extinguishing agent through the hose when the main valve is opened.
Gas cartridge fire extinguishers are specialised pieces of equipment with some specific advantages, and depending on your specific needs you may find them more suitable than common stored pressure models:
- Ease of recharging -- Once a stored pressure extinguisher is spent, it requires expensive and complicated refilling processed before it can be used again, and many users choose to pay to have their extinguishers professionally recharged. However, recharging a gas cartridge fire extinguisher is a simple case of changing cartridges, allowing a fire fighter to quickly recharge and return to a fire. This makes gas cartridge extinguishers very useful for industrial and mechanical applications where fires are larger and more likely to occur.
- Durability -- Gas cartridge extinguishers tend to be more robustly built due to their frequent industrial use. In addition, if a gas cartridge extinguisher is accidentally pierced, it will only release a stream of harmless gas, while a pierced stored pressure extinguisher will expel all of its contents (and potentially parts of the extinguisher body itself) in explosive and highly dangerous fashion.
- Ease of inspection -- Unlike a constantly pressured stored pressure extinguisher, gas cartridge extinguishers can be easily disassembled for inspection without inadvertently expelling the contents of the extinguisher.