Video: Finding Leaks in Your Vacuum Furnace – Part I

When it comes to finding leaks in your furnace, it can be a true art form. One of our most common customer questions concerns how to find a leak using a helium mass spectrometer. Which is why, during Ipsen U, we show attendees firsthand the step-by-step process.

However, it is such valuable and useful information to have, we figured why not share a short video explaining it to all of you.  Below is a video tutorial, given by Josh from Ipsen’s Quality Control Department, which details how to perform a leak check, from calibrating the helium mass spectrometer to determining what exact part of the furnace is the source of the leak.

Also, watch out for our upcoming post, Finding Leaks in Your Furnace – Part II, where we discuss vacuum valves – a common culprit for causing leaks.

Visit Ipsen’s YouTube channel for more videos.


  1. When stating in this video that helium rises, is false. Helium in fact is in the air we breath, so if all helium rises we wouldn’t be breathing it. Helium is actually displaced everywhere. Furthermore, you do not have to start spraying helium from the top of the vacuum down. If you had a downdraft when spraying, you would want to start from the bottom up, right? Starting from the leak detector forward would be where I would start from. Mass Specs can leak themselves so if it were leaking you would find the leak very quickly.


    1. Hello Chris,

      While the Earth’s atmosphere is comprised of many different gases, the percentage of those gases change as you go up in the atmosphere and/or with temperature fluctuations. However, when we stand on the Earth’s surface, the atmosphere is primarily comprised of nitrogen (78%) and oxygen (21%), which is what we breathe and what supports life.

      Although helium is one of the most abundant elements in the universe, the majority of it exists outside of the Earth’s atmosphere. In addition, helium is considered lighter than air and nitrogen (for example, a helium balloon let go by a child floats away).

      The fundamental reason that helium is used in the leak-checking process is two-fold:

      1. It provides a non-destructive testing method.
      2. The percentage of helium in Earth’s atmosphere at ground level is nearly non-existent, thus making helium trace gas an excellent tool for leak checking your equipment.

      Thanks for checking out our blog!


  2. The leak detector (LD) will clear the leak faster after helium spray is removed, if you hook the LD in front of the booster pump.
    What is the reasoning on hooking the LD between the booster and mechanical pump?


    1. That’s a great question Nathan. We connect the leak detector (LD) between the booster and pump for a couple reasons:
      1) It’s the discharge side of the booster so the LD performs well at the pressure there
      2) It’s an easy original equipment manufacturer (OEM) inlet hookup
      3) It’s where you have maximum pumping capability furthest downstream of your pumping system

      We don’t connect upstream of the booster due to the pressure there, but there are several variables that affect how fast helium is removed. Here are a few:
      1) Was the LD calibrated correctly?
      2) How much helium was sprayed?
      3) How big is the leak?
      4) Was helium trapped in the oil of the pump on the LD?

      Thanks for checking out our blog!


  3. Covered some interesting points for a 101 start. The statement that “leak detection is an art and not a science is most true”. I suppose in a future post you will point out the final test is the furnace “rate of rise test”. The He mass spec is not the final authority.


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