Varian 938-41 Porta-Test Helium Gas Leak Detector



ITEM MODEL: Agilent Varian 938-41 Helium Leak Detector with Varian SD-200 Diffusion Pump

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Agilent (formerly Varian) 938-41 Helium Leak Detector Machine


ITEM MODEL: Varian 938-41 Vacuum Leak Detector

CONDITION: This equipment was previously used by an oscillator manufacturer. This item is fully tested and in working condition.

DESCRIPTION: The Varian 938-41 Porta-Test Helium Leak Detector is based on the Contra-Flow principle - a proven technique that takes advantage of the differences in maximum pressure ratios produced by the diffusion pump for gases of different molecular weights. This principle is implemented in the 938-41 leak detector by introducing helium (and other inlet gases such as those resulting from a leak in the test piece) into the diffusion pump foreline rather than into the "normal" pump inlet as in conventional leak detectors. Helium, having a much lower pressure ratio than other gases contained in air, diffuses backwards through the diffusion pump to reach the sensing tube where it is detected as a leak in the normal manner. Although the mechanical pump is also attached to the diffusion pump foreline and removes all inlet gases, including helium, there is no appreciable loss of sensitivity in the 938-41 leak detector.


  • Varian 938-41 Helium Leak Detector
  • Cables and Connectors
  • Varian SD-200 Diffusion Pump

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Our Guarantee

We inspect and test every piece of equipment we sell, and we capture the testing process in our pictures and videos. This usually provides our clients with the assurance that they need.

If you are interested in a particular piece of equipment, and would like to see the results of additional tests that we have not performed, we offer the following services:

  • Contact us to arrange an appointment at our Toronto Canada head office, where you may inspect and test the equipment yourself.
  • If a visit to our office is inconvenient, you may provide us with step-by-step testing instructions. We will then carry out those tests and capture the process via pictures, video, or live video stream.

After your equipment purchase, if you are not completely satisfied, our Guarantee offers you a 30 day return period. During this period, you may return the equipment to us with no questions asked, we only ask that you cover return shipping costs and a 20% restocking fee on our invoice price. 

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