Tutorial: How to Find the Vacuum Leak in Your Freeze Dryer Manifold Valve

Having issues with your freeze dryer? Our troubleshooting guide may be a help! 


Finding a pinhole leak in one of your manifold valves is a serious pain. Even a single leak can send your lab's productivity into a tailspin if your freeze dryer can't hold a vacuum sufficient for your needs.


While tools like helium leak detectors make it much easier to locate leaks, such tools are quite expensive. This workaround sidesteps the need for a detector and costs virtually nothing. By covering each valve with foaming hand soap, microscopic leaks will be temporarily plugged, thus allowing you to easily narrow down which valve

needs to be replaced by monitoring the vacuum pull.

Check out our Troubleshooting Guide 

Materials Needed

  • Foaming hand soap
  • Cup
  • Manifold valve stopper
  • Clean rags



    1. Power on your freeze dryer and vacuum pump. Take note of how low the vacuum can pull.
    2. Plug the first manifold valve with the stopper to prevent soap from getting inside it.
    3. Wrap clean rags around the bottom of the manifold to soak up soap
    4. Fill the cup all the way up with foaming hand soap.
    5. Cover the plugged valve with the cup of soap, making sure to engulf the entire valve with foam.
    6. Monitor the vacuum pull on the freeze dryer. If it suddenly starts dropping rapidly, then you've found the valve that needs to be replaced.
    7. Repeat steps 2 through 6 on each valve until you've found the faulty one.


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