The choice between a permanent pressure extinguisher and an auxiliary pressure extinguisher depends on a number of factors, including the type of fire you're likely to encounter, the environment in which the extinguisher will be used, and specific maintenance and handling preferences.
What are the 2 pressure modes of an extinguisher?
1. Permanent pressure extinguisher
How it works :
- Principle: In a permanently pressurized extinguisher, the extinguishing agent (water, foam, powder, etc.) is kept under pressure in the tank by a propellant gas (usually nitrogen or compressed air) contained in the same tank.
- How to use: Pressing the release handle immediately releases the extinguishing agent.
Advantages :
- Simplicity: easy to use, with just one action to perform (press the handle).
- Cost: Generally less expensive than auxiliary pressure extinguishers.
- Maintenance: Easier to check, as pressure is visible on the pressure gauge.
Disadvantages :
- Service life: Pressure may decrease over time, requiring more frequent checks.
- Leak hazard: If the pressure gauge indicates low pressure, the extinguisher may not be effective.
2. Auxiliary pressure extinguisher
How it works :
- Principle: In an auxiliary pressure extinguisher, the extinguishing agent and the propellant gas are in separate compartments. When the extinguisher is activated, the propellant gas (stored in an internal or external cartridge) is released to pressurize the tank containing the extinguishing agent.
- How to use: First pressurize the device by striking the gas cartridge, then activate the handle to propel the extinguishing agent.
Advantages :
- Reliability: Less risk of pressure loss over time, as propellant is only released at the moment of use.
- Long service life: The extinguisher remains under pressure only when in use, reducing the risk of leakage.
Disadvantages :
- Complexity: May require training for correct use, as there is an extra step compared to the permanent pressure extinguisher.
- Cost: More expensive to purchase and maintain.
Typical uses :
- Industrial environments: Particularly suited to industrial or commercial environments where reliability and longevity are crucial.
- Specific applications: Used in situations where storage conditions may vary, such as outdoors or in vehicles.
CO2 extinguishers: permanent or auxiliary pressure?
Technically, a CO2 extinguisher is a permanently pressurized device. In fact, the device is constantly under pressure and has a pressure gauge to control it.
However, it differs from a conventional permanent-pressure device in that the CO2 contained in its body serves as both propellant and extinguishing agent.
It is effective on Class B and electrical fires.
