Application Note

Application Note: 030707
Kayden Instruments

Oil Water Separation Tank


Interface (Level) Detection: Oil / Water, Separator (Treater) Tank


Kayden CLASSIC 800 Series Thermal Dispersion Flow, Level, Interface & Temperature Switch & Transmitter

Classic 800 Display Panel
Display Panel
Pump Detection Oil Water

Oil is pumped from the well (or well storage) into the (“knock-out”) tank to separate the oil from the water and debris (sand, etc.). The interface (level) switch controls the (water) drain valve by energizing / de-energizing one of the internal relay contacts as the switch reacts to the material difference of the oil / water.

In oil / water interface applications the level switch must:

  • Resist failures caused by corrosion and / or “sludging” damage to the sensor.
  • Not react slowly or intermittently due to coating of the sensor.
  • Easily be configured (programmed, adjusted) by the user to achieve the optimum balance between response time and sensitivity to prevent tank overflows, oil in the drain line and unwanted cycling of the drain valve.

The Kayden CLASSIC 800 Series Thermal Dispersion Flow, Level, Interface Switch is used to provide the critical control for interface level in the tank.

Unlike float, paddle or gap switches Kayden switches feature all-welded sensors, no-moving-parts design and true digital electronics in a rugged package that is not bothered by coating of the probe and will not drift, seize or ever require calibration.

  • Easy, front panel controls and display make set up fast and easy.
  • The switch may be set to activate or deactivate the pump or feed valve using either of the independent relay contacts or the 4-20mA analog output.
  • Each relay contact may be configured with a digital time delay to pre-set tank drain cycles based on tank capacity.
  • To accommodate different mounting positions and tank configurations (screens, weirs, etc.) Kayden switches are available with several types (Threaded Insertion, Flanged, and Packing Gland & Ball Valve) and sizes (no premium charge for “custom” insertion lengths).
  • The self-diagnostic function runs automatically and continuously monitors all parts and functions of the Kayden switch. In the event of any error, the relay contacts de-energize and the FAULT alarm is activated and displayed on the front panel via the 4-20mA signal and via Modbus to the RCM software.
  • The Kayden RCM software (provided free on request) may be used (via Modbus RS-485) to continuously trend the fill / drain cycles of the tank.
Classic 800 Display Panel
Display Panel

Display Panel Indicators:

Relay 1

On steady when Relay 1 is energized

Relay 2

On steady when Relay 2 is energized


Indicates a self-test error or fault condition

Set Point 1

On steady when viewing Set Point 1

Set Point 2

On steady when viewing Set Point 2

Run Mode

Flashing when switch is operating


Flashing when the Start-up Bypass Timer is active

Thermal Signal

Displays Thermal Signal

The Thermal Signal increases as:


The flow rate increases


The sensor is submerged


The sensor is submerged by the second liquid of greater thermal conductivity

Applicable CLASSIC 800 Models

Classic 810
Classic 810
Classic 812
Classic 812
Classic 814
Classic 814
Classic 816
Classic 816
Classic 828
Classic 828
Classic 830
Classic 830
Classic 832
Classic 832

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