Fire Extinguishers Close-up

Firing Mechanism
All extinguishers have pins or pull tabs that have to be removed to activate the unit. This feature prevents false activations. Some of our testers had difficulty removing the pin because it was held in by a thin sacrificial plastic tie. We found most extinguishers had two levers that are squeezed together to activate. This is in contrast to the smaller 5-BC units designed for personal watercraft, which use a more simplified firing mechanism. Kidde uses a plunger mechanism and First Alert uses a trigger to activate their unit. Both are designed so that the firing mechanism does not extend past the width of the cylinder.

Gauges
There is a gauge on most extinguishers to measure the pressure of its contents. A fire extinguisher can be "overcharged" meaning the contents are under too much pressure, "discharged" meaning that there is not enough pressure to work correctly or "in the green" which means that the unit is properly charged. The standard round gauge was found on all but the personal watercraft units. Over time, or after it has been used, a fire extinguisher will loose pressure and will cease to work properly.

Most of our test extinguishers were not rechargeable. A rechargeable extinguisher can be taken to a service station for maintenance. If it is not rechargeable then it should be discarded when the gauge reads ‘discharged’ or it has been in service for 12 years from manufacture.

Mounting
The time it takes to find a fire extinguisher in a cluttered locker could mean the difference between saving your boat or having to jump overboard. A properly mounted fire extinguisher should be at every exit and near the engine compartment. This keeps your back to your escape route and an extinguisher ready near the likely sources of fire aboard. In the galley, an extinguisher should be mounted so you do not have to reach over the stove.

On open motorboats, fire extinguishers should be mounted in an easily accessible location. A non-marine-rated fire extinguisher could have parts that corrode or do not secure it firmly to a moving boat. Be sure to purchase a marine-rated fire extinguisher that has a noncorrosive metal or plastic bracket that can secure it firmly to a vertical surface.

Partial Discharge
Fire extinguishers are designed to rapidly release fire retardant onto their target. When activated, the firing mechanism pierces a gas cylinder exerting additional pressure in the cylinder propelling the retardant out of the open nozzle. During our test we found that a partially discharged dry chemical extinguisher was inoperable after a few minutes. If you have a flare up after several minutes, a partially discharged unit might not work. It is important to replace or service the extinguisher as soon as possible.

The First Alert shown here has a plastic tie to secure the pin, the plastic tie must be broken in order to remove the pin.

An operable extinguisher will have a pressure gauge reading "in the green".

The Kidde PWC model's yellow clip must be remove before depressing the green/white plunger. To test the unit's pressure, push the plunger down with the yellow clip in place. If it doesn’t return to its original position then the unit should be discarded

The First Alert PWC model has a pull pin that must be removed before the trigger can be pressed. The green button on top is used to test the pressure. If it does not pop back after it has been depressed then the extinguisher should be discarded.