Chinese pump first run report.

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Pascal Mueller
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Re: Chinese pump first run report.

Post by Pascal Mueller »

@Dennis: You said that "generally ethyl alcohol - absolute is best", what do you mean by absolut? Do you mean the brand? Like absolute wodka? If so: Why not go to your local pharmacy and just buy pure ethanol? At least in my country you can get 98% ethanol over the counter. (You could even drink it - there is also the one that you can't drink.) Just tell them you need it for tinctures.
William Pete
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Re: Chinese pump first run report.

Post by William Pete »

That's a good price on the pump, I believe I saw this one before combing through ebay and thought that it may not do the job as some of the used Edwards pumps were present in a lot of other jerry rigged builds like what I am going for.

I'm definitely going to keep this one in mind as I move forth.
george44
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Re: Chinese pump first run report.

Post by george44 »

Finn Hammer wrote: Wed May 17, 2017 10:38 am IMG_20170517_160046.jpgI received the Two-stage rotary vane pump the other day,
http://www.ebay.com/itm/2-stufig-Vakuum ... 1867425448
and was soon getting excited, since the label quoted two different values for acheivable vacuum.
either 0.004 Millibar, which corrresponds to 3 millitorr, but also 5 Pascal, which corresponds to 37 millitorr.
In the listing, it quoted 0.3 Pa which corresponds to 2.2 millitorr. What to expect?
Fortunately, the DigiVac LightBarVac meter arrived today, so at last I could start to get a feeling about the capability of the pump.

With everything in place, the pump drops down to, 5 micron, and within a minute or so, levels out at 1-2 microns, That is not so bad is it?

On the negative side, the pump does not have a ballast valve. I have no experience with vacuum whatsoever, and am unable to access whether this is going to be necessary pumping my 10" sphere, but time will tell. I want to buy here as it looks like a Death Star from Star Wars.
I will probably dismiss this pump to vacuum jar duty, though, and get a proper lab pump, because this one is quite noisy, starts to get on my nerves already.....

Cheers, Finn Hammer
Hi Finn! Thanks for sharing your experience with the Chinese pump. It sounds like it is performing well so far and you have a good vacuum level. It is understandable that the noise could be a bit too much, so it might be worth getting a proper lab pump to use instead. Have you considered any other options? Good luck with your 10" sphere!
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Richard Hull
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Re: Chinese pump first run report.

Post by Richard Hull »

Revisiting a now ancient post by George 44 who didn't read the rules regarding the use of only real names and not handles.

Since this ancient posting, Finn has become one of the finest and most successful of fusioneers to ever land here. I haven't heard much from him of late, but he really took performance and excellence to a new level.

Should you actually change your name to a real given name and stay with us, We never use block quotes. Why? We are far too smart to need them as we have read all the preceding posts in the thread and have good memories in addition to being smart.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Jerry Biehler
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Re: Chinese pump first run report.

Post by Jerry Biehler »

I have a few 1/4 NPT and a 1/8NPT on my coating system and got it down to 6.6^-7 the other day. The TC Gauge tube initially leaked when I checked it with a helium leak check with an RGA, went away when I tightened it up. So NPT is *ok* but if you have a leak it is probably the first place to look.
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Richard Hull
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Re: Chinese pump first run report.

Post by Richard Hull »

Jerry is correct, NPT points in any vacuum system are best left to the foreline, (TC gauge, typically), and shunned if possible beyond the foreline.
Many folks who can't afford a high vacuum gauge use a TC gauge on their fusor chamber. This is ,naturally, most often after the secondary pump, (diff, or turbo). This can be a real bear to seal successfully, but as Jerry notes, can be secured with effort.

To illustrate, If have seen many folks, new to vacuum, fail to even seal their foreline TC gauge correctly which is relatively easy to do.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Peter Schmelcher
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Re: Chinese pump first run report.

Post by Peter Schmelcher »

As I recall the ballast value introduces air into the pump's second stage so that water gas and other condensable gases do not compress back to a liquid or at least partially get pumped out of the oil along with the ballast air. That oil drying process should also work if you bleed ballast air into the first stage. The catch is you can't dry the oil at the same time as you pump down the chamber.
-Peter
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Richard Hull
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Re: Chinese pump first run report.

Post by Richard Hull »

True! You can't clean the oil of water and other volatiles by ballasting and pumping at the same time. To clean and clear the oil, blank off the fore pump and open the ballast all the way and run the pump for a long time. Note: you better have an oil mist filter on your pump or vent the pump to the outside world. Way back in the 90's I learned this the hard way. I ballasted and ran the pump indoors ballasted and blanked for 2 hours. I came back and found the room in a choking fog of oil vapor. Bad deal! Of course it helped taking the pump from a bottom of 13 microns to 3 microns.

You would probably be better served by just putting in fresh oil.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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