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9311 Pneumatic & Electric Liquid Level Switch

The Wellmark Series 9311 is a Pneumatic Snap Acting or Electric Hi/Lo Level Switch. This switch combines the user-friendly features of our Model 2001NB with the rugged external cage of the Model 9321. Together these attributes make the 9311 a robust, reliable Level Switch for the control of liquid level in oil and gas production equipment such as Gas Compressor Scrubbers, Separators, Safety Systems, etc.

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9311 Pneumatic & Electric Liquid Level Switch


  • Pneumatic or Electric
  • Weather Proof Case
  • Left or Right Hand Mount
  • Direct or Reverse Acting
  • 304 and 316 Stainless Steel Internals
  • NACE Process, Standard
  • Electric Option Available (Consult Factory)


  • Process Connection: Screwed 1″ NPT. Butt Weld 2.00″, Socket Weld 1.00″, Flanged (Consult Factory)
  • Temperature Rating: -20˚F-400˚F
  • Max. Working Pressure: 2500 psi
  • Pilot Action: Pneumatic-Snap (On/Off)
  • Minimum Air Supply: 20 psi
  • Minimum Specific Gravity: Pneumatic-0.5
  • Supply & Output Connection Size: Pneumatic- 1/4″ NPT, Electric- 1/2″ NPT

Level Control

  • Box: Die Cast Aluminum
  • Pilot: Aluminum w/S.S. Internals
  • Gauges: Brass (S.S. Optional)

Cage/body assembly

  • Cage: Cast Steel
  • Body: 1018 Steel
  • Displacer: S.S.
  • Displacer Arm: 304 S.S.
  • Seals: Viton®

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