Over the last couple of years, it’s become apparent that storing dry chemical fire extinguishers in a vertical position on boats may be a mistake. This is because the motion of a boat can compact the chemicals in vertically stored fire extinguishers into a solid block. This means that when you attempt to activate the extinguisher, it’s possible that it will not discharge.
The solution is to store them in a horizontal position where the motion of the boat shakes the chemicals back and forth in the cylinder and does not compact the chemicals. To check on whether your extinguisher is in working order, make sure the pressure gauge needle is in the green, and when shaking the cylinder you can hear the contents moving inside. You may also invert the extinguisher and hit it on the bottom with a rubber mallet. In some cases that will loosen the contents enough to insure the unit will work. If there is any doubt, dispose of the extinguisher in a proper manner and replace it with a new one(s).
To be on the safe side, it is also advisable to replace your fire extinguishers every seven years if they are not refillable.
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