OPL Series

  • Combination Indicating Gage and Critical Pressure Limit Switches
  • High and Low Pressure Limit Contacts Are Visible and Adjustable
  • Panel and Surface Mount Versions
  • Indicating-only Murphygage® Available
  • Latching Control Relay Versions Available
Product Overview: 


The OPL-series pressure Swichgage® instruments are combination pressure indicating gages with adjustable low and high limit switches. Limit switches can be wired directly to electric pilot circuits to operate alarms, shutdown or start/stop of engines and electric motors.

Surface mount or panel mount enclosure is available for most versions. All versions feature a 4-1/2 in. (114 mm) dial for easy viewing. Adjustable limit switches are accessible from front of the Swichgage instrument. Limit contacts have self-cleaning motion to enhance electrical continuity.

Other versions available:

  • Gage-only without contacts (Murphygage instrument)
  • Swichgage instrument with built-in latching relay for start-stop operations.


Base Models

The OPLC is a surface mount, indicating, pressure gage and switch. Adjustable high and low limit, ungrounded contacts are used to operate alarm, shutdown or start-stop circuits. Pointer closure against either of the adjustable contacts completes the pilot-duty circuit.

An SPST toggle switch is provided to override the low limit contact for equipment startup. Suitable for engines or electric motors with appropriate Murphy magnetic switch or trans- former relay assembly.

The OPLCE features a panel mount square case. It has all the features of the OPLC except the low limit contact lockout.

The OPLG is an indicating-only pressure Murphygage instrument. Same as the OPLC except without switch (limit) contacts.

The OPLFC is a panel mounting version of the OPLC. It has all of the features of the OPLC except the low limit contact lockout. The lockout must be done externally through the con- trol circuit or with the optional “SA” lockout. The OPLFC is typically used in control pan- els such as for compressors, pumps, etc. This version can be environmentally sealed with either the “ES” or “OS” options. Contact lead termination is by pigtail wires.

The OPLFG is an indicating-only pressure Murphygage instrument. Same as the OPLFC except without switch (limit) contacts.
The OPLBP is a specialized version of the OPL series designed for start-stop operation of engines and electric motors. The pilot-duty limit switches are connected to an internal latching control relay for ON/OFF automation. Available for various voltages.

The OPLBPE is the same as the OPLBP except has a panel mount square case.