Abstract: A pressure maintenance device is connected to a fire protection sprinkler system having downstream piping that is exposed to freezing temperatures, and supplies a pressurized fluid to the downstream piping when the sprinkler system is in an inactivated state. When an outlet pressure sensor near an outlet of the pressure maintenance device detects that a pressure of the pressurized fluid downstream of an outlet regulator falls below a first predetermined pressure, the pressure maintenance device supplies the pressurized fluid in a primary supply mode or a secondary supply mode. The pressure maintenance device automatically switches from the primary supply mode to the secondary supply mode if a supply pressure sensor detects that a pressure of the pressurized fluid downstream of a first pressurized fluid valve, and upstream of the outlet pressure regulator, falls below a second predetermined pressure.

Abstract: A pressure maintenance device is connected to a fire protection sprinkler system having downstream piping that is exposed to freezing temperatures, and supplies a pressurized fluid to the downstream piping when the sprinkler system is in an inactivated state. When an outlet pressure sensor near an outlet of the pressure maintenance device detects that a pressure of the pressurized fluid downstream of an outlet regulator falls below a first predetermined pressure, the pressure maintenance device supplies the pressurized fluid in a primary supply mode or a secondary supply mode. The pressure maintenance device automatically switches from the primary supply mode to the secondary supply mode if a supply pressure sensor detects that a pressure of the pressurized fluid downstream of a first pressurized fluid valve, and upstream of the outlet pressure regulator, falls below a second predetermined pressure.