Separator differential pressure switch / sensor

Signals a plugged separator element by monitoring pressure drop across it.

Also called: separator dP · element restriction switch

Normally open, closes on rising dP (typical alarm wiring). Verify against the schematic.

How it works

Either a mechanical dP switch tapped before and after the element, or two transducers differenced in software. A new element runs around 2 – 4 PSI dP; change it above roughly 10 – 12 PSI.

Specifications

New element dP

2 – 4 PSI (0.15 – 0.3 bar)

Change-out dP

10 – 12 PSI (0.7 – 0.8 bar)

Contact

Pilot duty, SPDT typical

Parts you can order

• Generic industrial

  Separator differential pressure switch

  By dP set point (typically 8–12 psid)

  $70 – $260

Field test procedure

1. Ohm the contact at known dP and compare with the switch tag.
2. Confirm the tapping lines are clear — plugged taps make a good element look perfect or terrible.

Symptoms & probable causes

• Alarm with a new element
  Blocked sensing line, wrong switch setting, or an MPV stuck closed.