Emerson Fisher N100 Series 2 in. FNPT Bypass Valve, 25 - 75 PSID Spring

Emerson Fisher
Pump Size:
4 in.
Body Size:
2 in. FNPT
PSID Setting:
50 psig
PSID Range:
25 to 75 psig
33.00 LBS
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Emerson Fisher's N100 Series is designed for bypass on 2 to 4 in. size pumps, the N100 Series is widely used on both LPG and Anhydrous Ammonia (NH₃) applications. The throttling action of the N100 series allows only surplus pump discharge to be returned to the tank. A venturi flow passage gives a boost effect, permitting a greater valve opening for increased flow at the lower pressure build-ups when bypassing full pump output. These features help to give rapid, stable liquid transfer and reduce dangerous pressure pulsations. The valves contain only one moving part- the piston style inner valve.

An external sensing line is not required because tank pressure registers through a hole in the inner valve. Complete field servicing can be made without removing the valve from the piping.

Note: All N100 Series bodies have 1/4 in. FNPT tapped and plugged boss on the side inlet for either a pressure gauge or a hydrostatic relief valve and have a temperature rating of -20 to 160°F (-29 to 71°C)


  • Closing Cap
  • Pressure Sensing Orifice
  • Piston Inner Valve
  • Exclusive Venturi Passage


  • Pump Size: 4 in.
  • Body Size: 2 in. FNPT
  • PSID Setting: 50 psig (3.4 bar)
  • PSID Range: 25 to 75 psig (1.7 to 5.2 bar)
  • Maximum Inlet Pressure: 400 psig (27.6 bar)
  • Temperature Capabilities: -20 to 160°F (-29 to 71°C)


Instruction Manual (PDF Download)

Replacement Parts Sheet (PDF Download)

N100 Series Bypass Valve Schematic (PDF Download)