Application Note

Application Note: 0131107A
Kayden Instruments

Pump Monitoring & Protection


Pump Monitoring and Pump (motor) Protection


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

Provide a rugged and reliable means for pump protection and monitoring.

  • Shut down the pump (motor) when the inlet line is dry / empty.
  • Automatically re-start the pump when the flow of the process material is restored.
  • Provide an alarm when blockages occur in the pipeline.
  • React to changes in the flow rate & temperature if desired.

It is difficult to find one device that can be configured for a wide variety of flow conditions and will not require frequent maintenance.

To perform well in this application the flow switch must resist failures caused by:

  • Corrosion and / or “sludging”.
  • Vibration.
  • Water contamination - feed water and cooling water often contain high mineral content and sediment.
  • Electromagnetic interference from motors (etc).
  • Difficult and/or controlled access points limit monitoring and daily maintenance.
Pump Detection Monitoring
Figure 1 - Kayden CLASSIC used in pump protection / monitoring

Every Kayden CLASSIC 800 SERIES Thermal Dispersion Flow, Level, Interface & Temperature Switch & Transmitter is configurable by the user for flow, level, interface and/or temperature with air, gases, liquids or slurries. The digital electronics are configured by the user for each application and are 100% interchangeable.

  • Unlike float, paddle or gap switches, Kayden switches are built specifically for demanding applications, remote locations and harsh conditions while providing remote user access.
    • Easy Display Panel controls and an LED display make setup fast and easy.
    • No-moving-parts design and all-welded sensors eliminate drift and sensor failures.
    • Digital electronics provide precise adjustment and optimum repeatability. No calibration is required.
    • Automatic, continuous self-diagnostics with auto-alarm function.
  • The Kayden CLASSIC 800 may be set to alarm via either of the two (2) independent relay contacts and / or a 4-20 mA analog output, on flow (increasing) or no-flow (decreasing).
  • The heater power, range limits, and relay set point(s) are independently and incrementally configured and may be quickly and easily adjusted via the Display Panel push buttons (no trim pots!). This allows the CLASSIC 800 Series switch to achieve application-specific response times and to eliminate "nuisance alarms".

The Start-Up Bypass Timer makes it possible to disable the pump on low flow and have it restart automatically after a predetermined time.

  • The Start-Up Bypass Timer allows users to set the delay from 0 to 100 seconds, in 5 second increments.
  • The Start-Up Bypass Timer is a programmable feature of Kayden’s digital electronics and as such requires no additional wiring or hardware.
  • In the event of a power interruption the Start-Up Bypass Timer will automatically re-start the pump as desired at power-on or restart.
  • During the Bypass Delay both relays are energized regardless of their mode or the value of the Thermal Signal.

Figure 1 shows the Kayden flow switch installed as a “Target Switch” on the INLET side, and as an “Indicator Switch” on the OUTLET side of the pump.

It is almost always preferable to install the flow switch on the INLET side of the pump.

  • The flow will be (much more) linear on the inlet side and the probe (flow switch) is less likely to be affected by “low flow” that is actually seeping or “chugging” on the outlet side.
  • In this position the switch may be configured to react to a specific flow range or to indicate increasing / decreasing flow.

If the flow switch has been, or must be, installed on the OUTLET side of the pump.

  • The Kayden switch will work as a flow / no-flow indicator when installed on the outlet side. However, as turbulence will affect the switch, more care must be taken to properly configure the range (0% - 100% Thermal Signal) and set point(s) (relay 1 and / or 2) to avoid false indications.
  • When installed on the outlet side, significant changes in fluid temperature or composition (oil to water for example) may require an adjustment to the programming of the switch.
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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