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Jordan Valve Mark 51 Series Self Operated Back Pressure Regulator

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  • A larger diaphragm than a Mark 50 gives better sensitivity and more accurate regulation.
  • Used in applications such as steam, water, oil and gas.
  • Sliding gate technology prevents build up and reduces seat wear.

The Mark 51 series is a back pressure regulator that has greater accuracy and sensitivity than the Mark 50 thanks to it having a larger diaphragm.

Quick and accurate regulation is provided by the sliding gate design which has a shorter stroke than globe or plug designs. This also helps to reduce seat wear and noise during operation as the disc and plate are constantly in contact to minimalize turbulence.

It is available in sizes between ¼" and ¾" and has Cv’s of up to 4.4. The pressure set points range from between 0.03 bar and 11.7 bar (0.5 to 170 psi). Common applications include steam, water oil and use with gases.

The larger diaphragm is made from Stainless steel, Jorlon and Buna-N as standard with Viton as an option. The body is manufactured using Ductile Iron, bronze, cast iron, carbon steel or stainless steel. Available end connections included threaded, flanged and both socket and butt welds.

Mark 50 Series - Features and benefits

Mark 50 Series - Features and benefits

Key specifications

Sizes (1/4" & 3/8" sizes use 1/2" body with reducers)
  • Mark 50: 1/4" through 4" (DN8 through DN100)
  • Mark 50QC: 1/4" through 2" (DN8 through DN50)
  • Mark 51: 1/4" through 3/4" (DN8 through DN20)
  • Mark 50HP: 1/2" through 4" (DN15 through DN100)
End connections
  • Threaded – FNPT, BSPT, BSPP (1/4” – 2” only, DN8DN50)
  • AANSI Flanges (150#, 300#, 600#)
  • DIN Flanges (PN10/16, PN25/40)
  • JIS Flanges (upon request)
Spring housing
  • Ductile Iron — 1/4" - 2" (DN8 - DN50)
  • Ductile Iron — 2-1/2" - 4" (DN65 - DN100)
Body materials
  • Ductile Iron
  • Bronze (1/2" - 2", DN15-DN50)
  • Cast Iron (2-1/2" - 4", DN65-DN100)
  • Carbon Steel (A216 WCB)
  • Stainless Steel (A351/CF8M)
Trim materials
  • 303SST — Standard on Ductile Iron, Bronze, Carbon Steel valves
  • 316SST — Standard on Stainless Steel valves
  • Monel, Hastelloy and other Alloys available
Seat materials
  • Jorcote on SST — Standard
  • Other materials available — Consult factory
Diaphragm materials
  • Stainless Steel - Standard
  • Buna-N - Standard
  • Viton - Optional
Servicesteam, water, air, oil, gas and chemicals
ShutoffANSI Class IV

Full specifications and further information can be found by downloading the spec sheet here.

Data sheets and manuals

Other features



The Jordan Valve Mark 51 Series Self Operated Back Pressure Regulator is widely used in the following industries:


Richards Industrials