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Fisher™ 2100 Liquid Level Switches
The Fisher 2100 on/off pneumatic switch and 2100E electric switch sense high or low liquid levels.
Typically, these switches pneumatically or electrically operate safety shutdown systems for field processing equipment in oil and gas production applications. The 2100 and 2100E switches use a displacer-style sensor located in an external cage that mounts on the outside of a vessel. Unless otherwise noted, all NACE references are to NACE MR0175-2002.
Fisher™ 2100 Liquid Level Switches


Area Classification
  • 2100: Group II Category 2 Gas and Dust
  • 2100E: Explosion Proof, Flame Proof, Dust Ignition Proof
  • 2100: PED, CUTR, ATEX
  • 2100E: CSA, FM, ATEX, IECEx, UL, CUTR, PED
Data Interface
2100E is wired
Max Outlet Pressure
  • 2100: 150 psi
  • 2100E: 11A, 1/4 horsepower at 125/250VAC, 5A resistive/3A inductive at 28VDC
Mounting Type
Process Vessel Mounted
Operating Temperature
Standard Temperature
Position Control
Power Source
125/250 VAC, 28 VDC
Process Control
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.


  • The switch is isolated and sealed from the process through a corrosion-resistant displacer and torque tube assembly for maximum reliability.
  • Materials are available for applications handling sour fluids and gases. These constructions comply with the metallurgical requirements of NACE MR0175-2002.
  • The 2100 and 2100E switch construction comes in a left-hand as well as a right-hand mounting version.
  • The explosion-proof, hermetically-sealed 2100E switch is offered as both a factory mounting and as an electric switch retrofit to the proven 2100 switch.
  • The displacer cage has two 1-inch NPT pipe plugs that can be removed and relocated for horizontal, instead of vertical, equalizing piping, or for installation of a bleed or drain valve.
  • Switching action for the 2100 and 2100E switches is field-reversible from high-level to low-level, or vice versa without additional parts.