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Background

I have a beginner question concerning rotary vane vacuum pumps like this one: VIVOHOME 110V 1/3 HP 4CFM Single Stage Rotary Vane Air Vacuum Pump

Here are the pump specifications:

  • Voltage: 110V
  • Free Air Displacement: 4CFM
  • Ultimate Vacuum: 5 Pa
  • Intake Fitting: 1/4 &1/2 Flare
  • Oil Capacity: 350ml

The intended commercial use of this particular pump is for HVAC systems, although I'm not totally sure what the vacuum pump accomplishes in that scenario.

Question

I want to use a pump like this to hold a vacuum in a sealed chamber. Is this possible? Or is a rotary vane pump used exclusively to move fluid/gas?

In particular, I want to build a home cathode ray tube. A vacuum is required so that the electrons don't bump into air molecules as they travel down the tube. I'm not sure if 5 Pa is strong enough vacuum for this application, but the pump is so cost effective that I wanted to look into its operation.

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  • $\begingroup$ According to Wikipedia, the cathode tube vacuum is typically around 0.01 Pa (about two orders of magnitude less). $\endgroup$
    – NMech
    Dec 26, 2021 at 14:43
  • $\begingroup$ @NMech Yes, but it's not clear if this is the necessary pressure or just industry standard. I'm just making something for fun, it's ok if it's not optimal. I'm still curious if the pump listed above can maintain a 5 Pa vacuum for a sealed container $\endgroup$
    – nwsteg
    Dec 26, 2021 at 14:45
  • $\begingroup$ This is just a guess, however since its not its intended use, I doubt that it will be able to even reach the 5 Pa. $\endgroup$
    – NMech
    Dec 26, 2021 at 15:07
  • $\begingroup$ Perhaps it won’t be the pump but what you use to connect to the chamber… $\endgroup$
    – Solar Mike
    Dec 26, 2021 at 16:00
  • $\begingroup$ Sorry, could you elaborate on that? $\endgroup$
    – nwsteg
    Dec 26, 2021 at 17:51

1 Answer 1

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I have the same pump and I use it to hold (no flow) vacuum without any problems (my use case is to hold vacuum while in epoxy mixture so that all bubbles can be extracted before pouring it into the mold, which usually takes 30min). But don't expect to get 5 Pa from this pump, I'd say 50 Pa is more realistic.

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  • $\begingroup$ Thanks! Can I ask how long it takes to achieve 50 Pa? And what do you use for a vacuum chamber/vessel? $\endgroup$
    – nwsteg
    Dec 27, 2021 at 19:41
  • $\begingroup$ It takes about 5-10 minutes to empty a 5L stainless steel chamber to below 100Pa, after that it's hard to read. Chamber has a acrylic top covered with rubber seal and a hole on top with fitting to attach the pump. $\endgroup$ Dec 27, 2021 at 20:24

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