Patent ID: 8720591

Claim:
A method of reducing corrosion in a dry pipe fire sprinkler system, the dry pipe fire sprinkler system having a piping network, at least one sprinkler connected with the piping network, a source of pressurized water and a dry pipe valve coupling the source of pressurized water to the piping network, said method comprising: pressurizing the piping network to a first pressure level with pressurized nitrogen from a nitrogen generator or a nitrogen gas storage vessel, said first pressure level greater than a trip pressure or supervisory pressure of said dry pipe valve; increasing the pressure with the pressurized nitrogen to a second pressure level, the second pressure level being greater than the first pressure level; and venting gas from the piping network with a gas vent when the pressure reaches the second pressure level, wherein oxygen in said piping network is at least partially replaced with nitrogen; and wherein the gas vent comprises a float valve or an electric liquid sensing control unit that allows gas discharge but not liquid discharge from the gas vent.