Parallel diffusion pumps.

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Marko Kuzmanovic
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Parallel diffusion pumps.

Post by Marko Kuzmanovic »

Would it be possible to run two diffusion pumps in parallel if properly controlled? Say each pump with a inlet valve both connected to a cold trap and then to the vacuum chamber?
This is for a large vacuum chamber and these pumps are what is available.
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Richard Hull
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Re: Parallel diffusion pumps.

Post by Richard Hull »

The key is with proper operation control and plumbing, I would imagine parallel pumping is possible. I would never try it, but it sounds like your back is against the wall.

Richard Hull
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Maciek Szymanski
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Re: Parallel diffusion pumps.

Post by Maciek Szymanski »

One of the large four beam interaction chambers at IPPLM was pumped by two 2000 l/s diffusion pumps in parallel:


83FE9BD5-B0D7-4011-81D0-54CAE5222C23.jpeg
The arrow indicates the first pump flange with the forevacuum bypass valve. The second pump is beyond the picure frame connected to the same large tube. I even still have those 500 mm manifolds in the stockroom at work. When I talked with Leybold representative he told me that they just set up a vacuum system for industrial glass plating using not less than ten 3000 l/s turbos in parallel...

So definitely possible. For other hand you must have a REALLY big chamber or an enormous leak. In the laser lab we have the optical compressor chamber of more than 1 m3 volume which is pumped by a single 300 l/s turbo backed with a small scroll. It gets down to 1e-6 mbar in 30 to 40 minutes. The most of this time is pre evacuation by the scroll pump.
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ChristofferBraestrup
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Re: Parallel diffusion pumps.

Post by ChristofferBraestrup »

There is almost no upper limit to the size of diffusion pumps, wouldn't one larger pump usually make more sense?

If one "needs" a large leak - it's common to use multiple pumps in parallel, but having small orifices between their sectors of the vacuum chamber, a so-called differentially pumped system. This is often done on mass spectrometers and beam lines.

I'm curious about your application!
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Maciek Szymanski
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Re: Parallel diffusion pumps.

Post by Maciek Szymanski »

You can build huge diff pumps, but nobody can stop you from connecting few of those monsters in parallel to even bigger chamber. Like this Goddard Space Flight Center test chamber:


15781056425_1909845d22_k.jpg
(Sorry, can't stop myself)

Sometimes it makes sense to have more than one pump in parallel. It is possible to use just one pump to just maintain the vacuum, or switch the additional pump only, when there is lagre gas load (like heavily outgassing material in the chamber, pulsed gas jet etc.) and it's not possible to use the differential pumping. Oversize pump will use adequate high power heater which will be heating up the laboratory even when the full capacity is not needed. It can be a real problem in the laser lab.
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Dennis P Brown
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Re: Parallel diffusion pumps.

Post by Dennis P Brown »

Marko, we have rules here and using your full name is our first; please fix your personal information so your full name posts both for your threads and in your bio information.
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