Frequently Asked Questions (FAQ)
Pressure in the Ideal Gas Law (PV = nRT) is related to volume of the bottle (V), amount of gas in the bottle (n) and temperature (T). Therefore, as the temperature increases, for the volume and amount of the gas remaining constant, the pressure exerted increases. Conversely, as the temperature decreases, the pressure exerted decreases.
As working temperature of the extinguisher is normally -20◦C to 60◦C, thus the pressure in the extinguisher will vary as the temperature changes within the range, and therefore the needle is moving within the green zone of the pressure gauge.
Another method for checking the pressure within an extinguisher is by using a gas test kit.
a. Visual inspection on pressure gauge – ensure that the needle is inside the green zone.
b. Check that the pressure gauge is operating freely – using gauge test kit.
Minimum total capacity should be 45kg delivered from 1 or 2 extinguishers at the discharge rate of 1.35kg/s to 2kg/s.