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The Basics of Dry Chemical Fire Extinguisher Inspection

Posted on: November 13, 2013

A fire extinguisher that’s not well maintained is even more dangerous than no fire extinguisher at all. The valuable seconds you could waste trying to get it to work could literally be the difference between life and death. That’s why fire extinguisher inspections are so important—provided you have them done correctly.

Getting Started

The first step in a fire extinguisher inspection is a visual inspection. After making sure the pressure gauge is in the green zone, your fire extinguisher inspector will normally shine it up with a cloth, which allows him or her to simultaneously check for any dents, rust, or other forms of damage. After that, they will remove the hose and blow through it to make sure there are no obstructions, then inspect the handle, pull pin, and valve head assembly.

Next, the inspector will check to make sure the instruction-name plate is still legible. This plate will give you all the information you need to know to operate the extinguisher, including:

  • Letters and pictures of the classes of fires it can extinguish
  • The rating number to  indicate extinguishing capability
  • Information on how much dry chemical should be in the extinguisher
  • Temperatures at which the extinguisher will operate

The manufacture date, which can be located on the label, on the bottom of the cylinder, or stamped on the underside of the extinguisher, will tell you two important things about the extinguisher: when it needs to be hydrostatically tested and when it needs a “six-year tear down.”

Hydrostatic Testing

We’ve written about fire extinguisher hydrostatic tests in the past, so just to recap: the fire extinguisher cylinder is pressurized to a test pressure to make sure there are no pinhole leaks or hairline cracks and that the cylinder will be able to maintain pressure without breaking. Once the test is complete, the extinguisher will be dried out and a sticker will be placed on it, noting that it has been tested.

Six-Year Tear Down

A six-year tear down is also called an internal inspection. The extinguisher will be broken down and completely emptied of powder, all the parts will be cleaned, any defective parts will be replaced, and then the whole thing will be put back together.

The Importance of a Gross Weight Check

The final piece of a fire extinguisher inspection is actually weighing the fully charged fire extinguisher. The label will indicate how much dry chemical to add to the extinguisher and how high to set the pressure. Occasionally, the gauge will indicate a different optimal pressure than the label. If this happens, the gauge will usually have to be replaced—an incorrect gauge will affect the fire extinguisher’s discharge and rating.

Checking the gross weight of the fire extinguisher means weighing the entire unit—hose, nozzle, valve head, pin, tamper seal, and of course, dry chemical. A 5-lb ABC fire extinguisher will say something like “Fill with five pounds of ABC dry chemical…gross weight of 8 lbs. 5 oz +- 8 oz.”

This means that the lowest gross weight the fire extinguisher can have is 7 lbs, 13 oz. Any lighter means the inspector did not top off the dry chemical powder properly or did not have or use a scale. Remember—if the weight is too low, it will affect the rating of the fire extinguisher.

Proper fire extinguisher maintenance is essential for protecting life and property in your building in Maryland, Virginia, and Washington, DC. If you need a fire extinguisher inspection, call Guardian Fire Protection today.

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