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2nd-stage regulators

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.