Ultimate Guide to Fire Extinguishers: Testing, Inspections, Maintenance

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Most fires start out small enough to be easily put out with a fire extinguisher. Like any lifesaving equipment, it's critical to ensure that portable fire extinguishers are operable at all times and have people there who are properly trained to operate the extinguishers. As such, it's of maximum importance to understand the different types of fire extinguishers and how to properly maintain them.

Types of Fire Extinguishers

Different types of fire extinguishers are suitable for different fire classes. For a fire to exist, it needs the following three elements: fuel, heat and oxygen known as the fire or combustion triangle. Fire extinguishers are designed to eliminate one or more of these elements to put out a fire. That being the case, having the right type of fire extinguisher is critical to protecting lives and assets.

Here’s a breakdown of the different types of extinguishers and the classes of fire they’re suitable for.

Class of Fire

Type of Fire Extinguisher to Use

Class A:
The fuel source involves everyday combustible materials such as wood, paper, trash, plastics, and vegetation.

  • ABC dry chemical extinguishers
  • Pressurized water

Class B:
These fires comprise flammable liquids like oil, grease, gasoline and paint.

  • ABC dry chemical
  • BC dry chemical
  • Carbon dioxide

Class C:
Appear on energized electrical equipment like electrical wiring

  • ABC dry chemical
  • BC dry chemical
  • Carbon dioxide

Class D:
Involve combustible metals like zirconium, titanium, magnesium, and potassium.

  • D extinguishers only

Class K:
Cover cooking oils and fats

  • K extinguishers (for kitchen)

Note: An ABC fire extinguisher can be used on class A, B, and C fires.

Fire Extinguisher Inspection Procedures

The NFPA 10 requires fire extinguishers to be inspected when they're first installed and visually inspected once a month after that. Any competent person, knowledgeable about extinguishers, can carry out an inspection.

At a minimum, here’s what you should look for:

  • Make sure the extinguisher is located in its designated place. It should be easily accessible and not obstructed, with clear, visible signage.
  • Ensure the pressure gauge is in the operable range or position.
  • Check for structural damages like dents, cracks, or rust.
  • Weight of the extinguisher to make sure it is full.
  • Make sure the pin and tamper seal are in place and undamaged.

If any of the above conditions are not met, contact a certified fire extinguisher maintenance company for a thorough inspection. They’ll make repairs and replacements wherever necessary. Plus, it’s advisable to inspect extinguishers more frequently if placed in locations that are more prone to rust, impact, or tampering. And have your extinguishers serviced annually by a reputable fire company.

The annual inspection which is required to be done by a licensed fire suppression contractor should also assess the relative size and suitability of the extinguisher and include a tag on each extinguisher indicating the date of inspection and servicing. 

Maintenance Procedures

Unlike the monthly visual inspection, fire extinguisher maintenance needs to be performed by a certified person familiar with the requirements of the NFPA 10. Maintenance can be conducted once a year or when indicated by an inspection discrepancy.

Fire extinguisher maintenance typically involves a thorough examination of:

  • the mechanical parts of the fire extinguisher
  • extinguishing agent
  • means of expelling
  • the physical condition of the extinguisher

The maintenance procedures are detailed in the manufacturer’s service manual and have to be performed by trained and certified professionals. Brothers Fire & Security Monitoring can assist you with testing, maintaining, and refilling any fire extinguisher. Contact us to figure out the best fire prevention system for your building.

Hydrostatic Testing Procedures

A hydrostatic test involves an internal and external examination of the extinguisher. The extinguisher will be stripped down to its shell and filled with water at a specific pressure for a predetermined time to determine if there’s any leakage or distortion. Afterward, the extinguisher will be drained, dried, and reassembled if it passes the hydrostatic test. If not, the extinguisher must be discarded.The frequency of hydrostatic testing depends on the type of extinguisher you have and can be carried out after 6 or 12 years.

Hydrostatic tests can be dangerous when performed incorrectly and therefore have to be performed by trained, certified professionals equipped with the proper testing devices and facilities.