Identify this valve?

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David Kunkle
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Identify this valve?

Post by David Kunkle »

Hi all,
d002.JPG
d001.JPG
Bought this valve some time ago hoping to use it as a leak valve. Wondering if anyone knows anything about it or if it would be good for anything. No info on a search and not even a # stamped on it anywhere. Edwards is all I know for sure. It has a range of 18 turns on the knob. It seems to be functioning OK, but when it was connected to my chamber from maybe E-4 torr and higher pressure, it didn't seem to affect the vacuum gauge at all, even open all 18 turns. Wondering if the flow could be that low that it didn't show up or if my leaky chamber would mask the valve's flow. I suppose I could do the clear tube in water method to try and measure its flow.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
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Richard Hull
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Re: Identify this valve?

Post by Richard Hull »

This is, of course exactly what it looks like.....A needle valve. Pretty cool actually, but perhaps rather coarse in its action. The gear box and needle assembly allow some degree of fine control. The bottom piece is the key assembly. Is it clogged or dirty? That is your question to be answered.

Richard Hull
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Tom McCarthy
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Re: Identify this valve?

Post by Tom McCarthy »

Have one almost exactly like that, bought on Ebay and described as "Edwards Speedivac Needle Valve."

Tom
David Kunkle
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Re: Identify this valve?

Post by David Kunkle »

Do you have any idea what the flow range is for this valve? Thanks.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
Tom McCarthy
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Re: Identify this valve?

Post by Tom McCarthy »

Not sure. It's currently lying in my box of "to-be-used" equipment as I'm currently organising how I'm going to get my hands on deuterium. I can only assume that the meter reads from 0-100% flow rate and even then it seems to be free to rotate in any direction for any number of turns. I can't find any information online about it either, so it's going to take some intelligent experimentation to calculate its specs.

Tom
David Kunkle
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Re: Identify this valve?

Post by David Kunkle »

Don't know how close yours is to mine. But, if you look at the second pic, there is a small counter window just above 78 on the dial. It goes from 0 to 18 counting full turns of the large dial. My valve bottoms out solidly at 0 and tops out solidly at 18 turns plus 80. From 0 to 1880, the needle withdraws 1.5 mm. One number on the dial then should equal .0008 mm of movement of the needle. I was hoping this might flow low enough and be sensitive enough to meter gas into my chamber. Far as I can tell, it does not leak when I had it attached to my chamber, and it seems to be functioning properly when I had it apart- not clogged, etc. Yet, when I blow thru it full open, (yeah, I know- real scientific- best I could come up with without going to a lot more trouble) I cannot detect any flow. I'm wondering if it's malfunctioning somehow I don't understand, or if it's designed to flow extremely small quantities I can't detect without it being hooked to the chamber and gauges.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
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Rich Feldman
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Re: Identify this valve?

Post by Rich Feldman »

David:
At the leak rates you care about, do you really think blowing into the valve would tell you anything? Maybe with a hose on the other end, leading to a hollow needle, you could blow bubbles.
How about putting the valve back on your evacuated chamber, then connect the inlet to a bourdon-tube vacuum gauge and see if the needle eventually moves? (similar to manometer test, without the wetness).
All models are wrong; some models are useful. -- George Box
Tom McCarthy
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Re: Identify this valve?

Post by Tom McCarthy »

Well, Robin Whyte (fizz is his username) sent me the attached sheet. He tried to post it in PDF, but couldn't get it working so I said I'd try screenshotting it and posting that. Has most of the information we're looking for.

Hope it helps and thanks to Robin,
Tom
Attachments
Screen Shot 2015-02-02 at 18.27.14.png
David Kunkle
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Re: Identify this valve?

Post by David Kunkle »

WOW! Thanks for the info sheet. Google turned up recalvac.co.uk. It appears that Recal might have replacement parts for these. Turns out I have the LB2B extra fine control model.

"for gas bleeds into a vacuum chamber or a regulated leak to control pressure in a vacuum system." Just maybe we lucked out and have something good here.

Not sure what I was doing before, but I can in fact detect flow by blowing thru it wide open from 18 turns down to about 4 turns-which explains the .09 l/s max flow. (And now I also have to clean the valve again.) Below that is hopefully where it will come in handy for fusor work. Plus, there's always regulating the pressure on the tank side.

As Rich suggested, I'll have to measure the flow sometime soon- my chamber *might* be back from the weld shop tomorrow and *if* my rebuilt turbo (for the 2nd time) holds together.
If your experiment needs statistics, you ought to have done a better experiment.

Ernest Rutherford
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