Only CO2 needs to be tested every year--and that is to be weighed because CO2 has no gauge. Halon and others need to be checked VISUALLY yearly and pressure tested every 6 years. Halon does not displace oxygen, it interrupts the chemical reaction of the fire. Halon is expensive because it is no longer manufactured in the US and is intended for aviation use only as of the late 90's. Newer Halon extinguishers use nitrogen with Halon 1211 and aren't as effective as the original Halon 1211 and 1301 blend. You are correct that they are more prone to leakage with the nitrogen blend. I run and school complex and we use the Halon 1211/Nitrogen blend in all of our computer labs, dry chem and water everywhere else.
20:30:36 04/18/07
