Oil Water Detector

Written by Jerry Ratzlaff on . Posted in Instrumentation & Controls

Oil water detector, abbreviated as OWD, or cut probe is an instrument that measures the percentage of oil or water in a process stream.  When they are specified, the continuous phase needs to be determined.  For LACT applications, oil is the continuous phase.  

On a Piping and Instrumentation Diagram, a cut probe is characterized as an analyzer and contains an element (AE) and a transmitter (AT).  The cut probe sends an analog signal to the PLC which is used to for surveillance or process control.

Cut Probes can be used in:

  • Well test applications
  • Group test facilities
  • Custody Transfer
  • LACT Units
  • Pipeline
  • Drainage and urban runoff processing


Oil Water Detector Types



Capacitance level detectors are also referred to as radio frequency (RF) or admittance level sensors.



Microwave probes detect the amount of hydrocarbons in water.  This style of probe operate on the same principal as putting a Styrofoam cup filled with water in the microwave.  The water reacts differently than the petroleum based Styrofoam.  By sensing the way the microwaves react as the oil and water passes through it the amount of hydrocarbons can be measured with a very high accuracy.  The strength of a microwave probe comes from its ability to measure 0 to 100 percent water.  


instrument abbreviations