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DE ( Dead End ) Why set it

WCF

Help Support WCF:

What is Calibration and why set it?

The article below covers both the older V11 and Newer V16 controllers

The controller is designed to stop the pump when it detects that the pole valve has closed. We call this dead-end detection. Calibration is important because it is used to set the sensitivity of the dead-end detection: the calibration value will affect how quickly the controller stops the pump. When the controller has detected a dead-end, it will display ‘DE’ and temporarily switch off the pump.

The higher the calibration value, the longer it will take the controller to stop the pump. If the calibration is set too high, the pump will continue working and pushing against the closed valve for a much longer time after it is closed. During this time the pump will increase pressure unnecessarily. Once the pump is finally stopped, the dead-ended pressure will not rise any further, but it will be trapped by the pole valve. If the calibration is set very high (eg. 99) the controller may not detect the dead-end at all and the pump will only stop when the pressure switch activates (PS).
  • Correctly set calibration will mean the controller stops the pump when a valve is closed well before the pump pressure switch activates.
  • The ideal is to have the lowest calibration value possible to achieve continuous water flow.
  • When calibrating, connect your reel hose and pole/lance and open the valve to allow flow.
  • Ideally the controller should dead-end the pump within a few seconds of a hose valve or lance trigger being closed.
  • It is best to use the auto calibration function. Always set flow rate first to your preferred flow.
  • As flow rate increases, the calibration value will also need to increase as it needs to be less sensitive. Setting Cal too low can result in false dead-end detection and intermittent flow.
A higher calibration value makes the controller less sensitive at higher flow settings. This is because the pump is working harder when the valve is closed and pressure will increase in the hose very quickly. However, the controller should still dead-end the pump in a few seconds.

A high very calibration and high flow settings, for example set to 90 or above, will mean the controller will not dead-end the pump. Instead, the pump pressure switch will activate due to the high pressure build up (before the controller can detect a dead end). In this instance the controller will display PS.

Note:
Changing calibration does not change the flow rate of water to the pole/lance.

The controller does not activate the pressure switch. High pressure in the system causes the pressure switch to activate and the controller then reports what it sees.

If on closing the pole valve, the controller shows PS instead of DE, the calibration value is too high and should be reduced.

When a pump pressure switch activates, it will be under a high current load. The current arcs (like lightening) between the switch contacts and eventually will burn them out. Setting calibration correctly will protect the pump pressure switch because it will also operate less often, increasing its life.

In summary::

  • When a pole valve is closed, the controller should stop the pump and display DE.
  • However, if PS shows, reduce the calibration.
  • When setting calibration, do this at your preferred flow rate.
  • Connect hoses and ensure valves are open.
  • Running Auto Cal will give the most accurate calibration value based on the flow rate.
  • Altering calibration does not impact on flow.
  • Calibration affects how fast the controller will DE the pump.
  • If the Pump flow cycles on/off or if DE displays unexpectedly please recalibrate at the current flow rate
  • Where pumps are replaced, or different ID hoses and Jets are fitted please recalibrate
Please see the following video
Thanks to Squeaky Clean Dave for the video

Ian Sheppard
 
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