It is not possible to tell how safe a portable fire extinguisher is just by doing a visual inspection. The way an extinguisher is handled and the passage of time can have an impact on its efficiency. If not properly checked or maintained it can lead the fire extinguisher to malfunction or burst causing more damage than protection. In order to prevent his from happening it is mandatory for all fire extinguishers to be checked for proper use.
Hydrostatic testing is one method through which the efficiency of a fire extinguisher can be determined. The test runs a comprehensive check on the cylinder, shell and the hose assembly by checking for leaks or any structural flaws. It makes use of a liquid to test the complete equipment for pressure.
How does hydrostatic testing work?
The extinguisher valve is removed, once the inside of the cylinder is exposed the threads and the interior of the cylinder is checked for the presence of rust or corrosion.
Once the visual inspection is complete, the cylinder is placed in a steel chamber. The chamber is then filled with water at a normal pressure and temperature. A burette attached to the side of the chamber provides a zero reading. Then the pressure of the water is increased as it touched the interior of the fire extinguisher. As a result of the pressure buildup the cylinder would begin to expand. The water would then be pushed out of a small hole into the burette which reading starts to change.
Once the pressure is released the water is pushed back into the cylinder. Based on the reading observed by the professional, the extinguisher would be labeled as safe or unsafe.
A cylinder is considered unsafe if
- The water level in the burette keeps rising even when specific amount of pressure is increased.
- The shape of the cylinder becomes distorted ad it stretches. This is an indication that the metal of the cylinder is not resistant enough.
When do extinguishers need to be tested?
Extinguishers need to be tested based on the type of extinguishers you possess. However the usual time period includes an interval of two and five years.
It is necessary that the test should only be run once the visual test proves that everything is well and good with the cylinder.
For home owners and also for workplaces where the fire extinguishers have been tested the person in charge is expected to keep certain records. The records should include
- The name of the agency which carried out the pressure test and the date of the test as well
- It should also have the signature of the person who performed the test
- The serial number of the tested fire extinguisher in Brisbane
However the fire extinguishers should not be pressure tested in any of the following circumstances:
- The cylinder has become discoloured
- If the shell threads of the cylinder appear damaged
- When the cylinder shows any signs of rust or corrosion