|Second-Stage regulators reduce the outlet pressure from a First-Stage regulator [usually 10 psig (0,69 bar) to 11” water column (27 mbar)] in domestic installations. Vents are screened with standard orientation over the inlet, but other orientations are available. Vent adaptors, P212/P213, are available for non-threaded vents. Fisher Second-Stage regulators are painted palm green for easy identification.
Type R522 is designed for Two-Stage LP-Gas systems and listed by Underwriters Laboratories. Designed for domestic applications up to 1,375,000 BTU/HR, the R522 incorporates Fisher’s straight-through orifice flow design. Type R522 has an overall length of 6.13” (156 mm).
Type R522 contains an oversized relief valve and a large 3/4” screened vent to limit downstream protection to less than 2 psig (0,14 bar) in an overpressure situation as required by NFPA 58. Type R522 is normally adjustable from 9 1/2” to 13” water column (24 – 32 mbar), with a factory set point of 11” water column (27 mbar).
For easy system checks, the R522 has 1/8” built-in NPT gauge taps, orificed to a No. 54 drill size, on both the upstream and downstream sides. This regulator also features a large 3/4” drip-lip vent to reduce the chance of blockage by freezing rain or sleet when properly installed with the vent pointing down.
|Type R552 is designed for domestic applications up to 1,100,000 BTU/HR. This unit provides all of the same features as the R522 with a back mount design. The R552 has a 3/4” inlet and a 3/4” outlet connection.
Type R312 is designed for domestic applications up to 270,000 BTU/HR with an outlet adjustment range of 9 1/2” to 13” water column (24 – 32 mbar). It has an overall length of 4.13” (105 mm) and a flush-mounting boss. This compact design enables the R312 to be installed in convenient outdoor locations. The R312 has a 1/4” inlet and a 1/2” outlet connection.
Type R422 is designed for domestic and light commercial applications up to 2,025,000 BTU/HR. It has a large 1” NPT drip-lip vent and a 3/4” inlet and a 3/4” outlet connection.