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Fisher™ 4660 Pneumatic High-Low Pressure Pilot
The Fisher 4660 pneumatic high-low pressure pilot activates safety shutdown systems for flowlines, production vessels, and compressors.
This pilot is available with either single or dual set point capability, using switch points to maintain full output pressure when the process pressure is within the set point range. If the process pressure is outside this range, the pilot switches from full output pressure to zero output pressure. The primary switching mechanism in this pilot is a block-and-bleed relay assembly. This construction can be used in both block-and-bleed and bleed-only systems.
Fisher™ 4660 Pneumatic High-Low Pressure Pilot


Area Classification
Input Signal
Max Outlet Pressure
65 psig
Mounting Type
Remote Mount, Actuator Mount
Operating Temperature
Standard Temperature
Position Control
Process Control
Safety Certification
SIL 3 capable
Supply Media
Air, Natural Gas
Other Configurations
Contact your local Emerson business partner or sales office to learn about additional specifications or options for this product.


  • Repeatability meets the U.S. Minerals Management Service test tolerances referenced in Outer Continental Shelf (OCS) Order No. 5 and defined in the American Petroleum Institute (API) RP14C standard.
  • Simple modular construction, plus a line of pre-packaged parts kits, makes pilot maintenance fast and easy.
  • Construction materials have been selected to protect the pilot from corrosive environments.
  • The rugged Bourdon tube sensing element and shock-absorbing switch points dampen the effects of vibration.
  • Standard high-resolution set point adjustments are easy to set, non-interactive, and can be locked in place to maintain the desired set point.
  • One pilot provides either a high-low function or a single switch point, whichever the application requires.
  • A supply pressure test function is provided.
  • An N05500 nickel alloy Bourdon tube is available for those applications where the pilot must meet the requirements of NACE Standard MR0175-2002.