Tips & tricks

Detecting a leaking in-line solenoid valve

Regain power over your vacuum control

How to detect and clean a leaking suction in-line solenoid valve on your vacuum pump

Are you familiar with the problem that your pump creates a vacuum even though the stop button is activated? A simple solution may be to clean the electromagnetic in-line solenoid valve. This is because porous hose material or dirt from the application can sometimes build up on the valve seal. You can regain control of your vacuum control with minimal effort. Find out how easy it is in our blog post!


Which pumps does the tip apply to?

All vacuum diaphragm pumps with two-point control are equipped with an electromagnetic in-line solenoid valve on the vacuum connection. These include, for example, the PC 510 select or PC 520 select pumping units. These pumps start up immediately after being switched on. For this reason, an integrated digital vacuum controller controls the suction line valve and thus enables vacuum control. When vacuum is required, the valve opens accordingly; conversely, it closes. With the help of a graphical user interface, the user can easily press "Start" or "Stop" on the controller and set various parameters such as pressure and duration.

However, what if the vacuum pump draws vacuum even though the stop button is activated and the valve should remain closed towards the application? Then we recommend checking the in-line solenoid valve first. It is possible that dirt on the valve seat is preventing the valve seal from closing properly. Another possibility is that the sealing lip is defective.

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Watch practical tip in video

Checking + cleaning the in-line solenoid valve


  • Activated stop button on the vacuum controller
  • Hold the vacuum connection closed with your finger
  • Fluctuating pressure display on the vacuum controller → In-line solenoid valve possibly leaking


  • Switch off the pump
  • Unscrew the suction line valve
  • Clean the valve seat with a cloth to remove dirt
  • Reconnect and tighten the valve


  • Switch the pump on again
  • Hold the vacuum connection closed
  • Pressure display on vacuum controller unchanged → Error successfully resolved

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