Update on experiment
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- Real name: Steven Whittam
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Update on experiment
Hey
Just an updated on how I’m doing with experiment
Got down to 2812 micron with just pump
Friend at work as a vacuum pump so hopen to try double up.
Pump he has is better than cheap chines one I’m usen.
But slowly getting there
Just an updated on how I’m doing with experiment
Got down to 2812 micron with just pump
Friend at work as a vacuum pump so hopen to try double up.
Pump he has is better than cheap chines one I’m usen.
But slowly getting there
- Richard Hull
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Re: Update on experiment
You do have a nice gauge, at least. You also have either the worst pump in the world or the most number of leaks, real or virtual, that I might imagine.
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
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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Re: Update on experiment
I do Probly need a new plastic rim
Cause is a bit dodgy after didn’t put lid on right and lid got sucked in and ripped plastic seal in some places
Cause is a bit dodgy after didn’t put lid on right and lid got sucked in and ripped plastic seal in some places
Re: Update on experiment
Vacuum seals must be nearly perfect.
While compressible rubber seals such as O-rings with vacuum grease can cover many ills, they are still sharply limited. It only takes a small pinhole to make a vacuum unusable. Threaded pipe fittings, hairline cracks and pinholes, and a variety of other problems can also be an issue.
While compressible rubber seals such as O-rings with vacuum grease can cover many ills, they are still sharply limited. It only takes a small pinhole to make a vacuum unusable. Threaded pipe fittings, hairline cracks and pinholes, and a variety of other problems can also be an issue.
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Re: Update on experiment
Just got a new seal for lid
Will see how it gos when get a chance to run another test
Will check fittings ect aswell
Will see how it gos when get a chance to run another test
Will check fittings ect aswell
- Rich Feldman
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Re: Update on experiment
Good luck with that, Steven.
As Richard said, your very high ultimate pressure indicates that there's at least one major vacuum leak. It's happened to me. Have you tried listening closely to locate the leak?
Another way to measure the leak is to turn off the vacuum pump and see how fast the chamber pressure returns to atmosphere.
Some pump defects can let pump oil be sucked into the evacuated chamber when motor stops.
If that happens in your case, you can valve off the pump instead of turning off the motor.
Here is an effective but messy method for gross leak detection.
Brush some oil or grease or petroleum jelly around the outside of each seal, while chamber is pumped down.
Watch through your large clear lid, to see where the oil & maybe tiny bubbles are being sucked in.
Watch the vacuum gauge in case pressure drops when the leak is momentarily plugged with oil.
Don't overlook the joints in pipe between pump and chamber.
As Richard said, your very high ultimate pressure indicates that there's at least one major vacuum leak. It's happened to me. Have you tried listening closely to locate the leak?
Another way to measure the leak is to turn off the vacuum pump and see how fast the chamber pressure returns to atmosphere.
Some pump defects can let pump oil be sucked into the evacuated chamber when motor stops.
If that happens in your case, you can valve off the pump instead of turning off the motor.
Here is an effective but messy method for gross leak detection.
Brush some oil or grease or petroleum jelly around the outside of each seal, while chamber is pumped down.
Watch through your large clear lid, to see where the oil & maybe tiny bubbles are being sucked in.
Watch the vacuum gauge in case pressure drops when the leak is momentarily plugged with oil.
Don't overlook the joints in pipe between pump and chamber.
All models are wrong; some models are useful. -- George Box
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Re: Update on experiment
Thanks for advice
I’ll give it a go next time am at work in workshop
I’ll give it a go next time am at work in workshop
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Re: Update on experiment
Hey
Update with how been going
Last few tests only been getting to around 4.9000 mbar
Guess still some leaks
Probly need to wash seal to get any dust off
Anyway attached some pics
Update with how been going
Last few tests only been getting to around 4.9000 mbar
Guess still some leaks
Probly need to wash seal to get any dust off
Anyway attached some pics
- Rich Feldman
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Re: Update on experiment
Very nice pictures, Steven.
What if your leak is not from a dirty seal, but some place completely different from the seal you are thinking of?
Like an electrical feedthrough, or a vacuum hose connection, or you just have a defective vacuum pump?
Would be nice if you could close a valve between pump and chamber.
What if your leak is not from a dirty seal, but some place completely different from the seal you are thinking of?
Like an electrical feedthrough, or a vacuum hose connection, or you just have a defective vacuum pump?
Would be nice if you could close a valve between pump and chamber.
All models are wrong; some models are useful. -- George Box
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Re: Update on experiment
Hey
Attached picture of setup
Basically just a big pot with Perspex lid with rubber seal
Pump is rated to 3x 10-1 pa
Not sure what that means
Attached picture of setup
Basically just a big pot with Perspex lid with rubber seal
Pump is rated to 3x 10-1 pa
Not sure what that means
- Rich Feldman
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Re: Update on experiment
You can look up the conversion from pascals to whatever unit is indicated by your gauge.
One strong lesson from the first page of vacuum FAQs here:
The pressure "rating" of a rotary vacuum pump, even brand new, is generally very very optimistic. See FAQ for the reasons.
What happens when you connect gauge directly to pump with nothing else?
You must have tried that before bringing chamber into the picture!
One strong lesson from the first page of vacuum FAQs here:
The pressure "rating" of a rotary vacuum pump, even brand new, is generally very very optimistic. See FAQ for the reasons.
What happens when you connect gauge directly to pump with nothing else?
You must have tried that before bringing chamber into the picture!
All models are wrong; some models are useful. -- George Box
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Re: Update on experiment
Actually haven’t Tryed that... guess could give it a go
Will try gauge to pump in a little while
Well the fancy gauge was a recent addition
When relised the gauge that came with it couldn’t go past -30hg
Will try gauge to pump in a little while
Well the fancy gauge was a recent addition
When relised the gauge that came with it couldn’t go past -30hg
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Re: Update on experiment
Ok got to about 0.2500 mbar
- Mark Rowley
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Re: Update on experiment
We normally use mTorr or Microns for scientific vacuum work and I believe your electronic meter can toggle to those measurement units. If not, using an online conversion tool would be a good idea.
So that's around 188 mTorr which is still not good......better, but not good, especially if the measurement is taken at the pump. You should be able to attain at least 15 mTorr (0.020mBar). If your connection point to the gauge is sound, then you definitely have some pump issues.
Mark Rowley
So that's around 188 mTorr which is still not good......better, but not good, especially if the measurement is taken at the pump. You should be able to attain at least 15 mTorr (0.020mBar). If your connection point to the gauge is sound, then you definitely have some pump issues.
Mark Rowley
- Richard Hull
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Re: Update on experiment
Mark is correct, but even with a perfect pump, the connections and the chamber are usually the killers where all of the real leaks are to be found. The general rule is that with 10 microns at the pump entrance, (the head), You will never get that in any chamber unless it is tiny and connected directly to the pump. Anything in the chamber like insulated wire, plastics of any type, etc., will forever ruin the vacuum especially if there is any form of discharge taking place.
Richard Hull
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
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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- Posts: 103
- Joined: Fri Jan 24, 2014 8:45 am
- Real name: Steven Whittam
- Location: Melbourne/Australia
Re: Update on experiment
Ok thanks for advice guys
I have a bit of cash saved in joint account with mum
I’m thinking if I can talk her into letting me spend some would this pump be worth it
https://hvacdirect.com.au/vector-rd-160 ... cuum-pump/
Any advice or suggestions would be welcome
I have a bit of cash saved in joint account with mum
I’m thinking if I can talk her into letting me spend some would this pump be worth it
https://hvacdirect.com.au/vector-rd-160 ... cuum-pump/
Any advice or suggestions would be welcome
Re: Update on experiment
I am honestly a bit skeptical of that pump -- not that its a bad pump, but that there are probably better ones for a lower price.
- Rich Feldman
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Re: Update on experiment
Not so fast, Steven.
Today you get 4.9 mbar in the chamber, and 0.25 mbar with gauge on pump with nothing else. (Even in the second case you might be suffering from a connector leak or old vacuum pump oil.)
So as Richard said a couple posts up,
the vast majority of your unwanted pressure in chamber comes from leaks, in combination with vacuum hose too long and too narrow.
If you put God's own vacuum pump in place of yours, the reduction in chamber pressure would be inconsequential.
You and your mum's money would be much better spent dealing with the leaks, and getting a fatter hose for the pump you got.
Plenty of hints have been given in this very thread, not to mention all the FAQ's.
Call back when you can demonstrate chamber pressure less than 0.5 mbar.
Today you get 4.9 mbar in the chamber, and 0.25 mbar with gauge on pump with nothing else. (Even in the second case you might be suffering from a connector leak or old vacuum pump oil.)
So as Richard said a couple posts up,
the vast majority of your unwanted pressure in chamber comes from leaks, in combination with vacuum hose too long and too narrow.
If you put God's own vacuum pump in place of yours, the reduction in chamber pressure would be inconsequential.
You and your mum's money would be much better spent dealing with the leaks, and getting a fatter hose for the pump you got.
Plenty of hints have been given in this very thread, not to mention all the FAQ's.
Call back when you can demonstrate chamber pressure less than 0.5 mbar.
All models are wrong; some models are useful. -- George Box
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Re: Update on experiment
Did best I can to sort any leaks
Left pump running for 2 and half hours and made it down to 661 - 665 micron
Seems to be hovering between
It is a relatively cheap pump that came with chamber.
Did some looking and is rated to 25 micron apparently.
But I doubt that’s taking into account the 15 gallon chamber I’m using could be part of issue having to move so much volume.
Left pump running for 2 and half hours and made it down to 661 - 665 micron
Seems to be hovering between
It is a relatively cheap pump that came with chamber.
Did some looking and is rated to 25 micron apparently.
But I doubt that’s taking into account the 15 gallon chamber I’m using could be part of issue having to move so much volume.
- Dennis P Brown
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Re: Update on experiment
Glad your still working towards your goal. That shows commitment; however, with vacuum systems and leaks, one must also accept that there is a reason people use professional chambers, connections and vacuum pumps - saves vast amounts of time and efforts while finally allowing one to reach their desired vacuum conditions.
I have obtained very professional equipment via ebay and secondary sellers - these can very inexpensive if one waits and watches what is available - I obtained two multi-thousand dollar pumps for a few bucks - shipping was the real expense ($30 each.) Ditto on good (i.e. working) micron gauges and vacuum piping/connectors. I obtained a large vacuum shell that needed a 8 inch window - I simply bought a telescope glass blank, inexpensive glass drills and made a high voltage feed thru that was vacuum tight. Work arounds exist and can be done cheaply if one is clever.
Hope you succeed and obtain your end goals but creating micron grade vacuum systems is not easy to do without proper equipment - just no easy work-arounds.
I have obtained very professional equipment via ebay and secondary sellers - these can very inexpensive if one waits and watches what is available - I obtained two multi-thousand dollar pumps for a few bucks - shipping was the real expense ($30 each.) Ditto on good (i.e. working) micron gauges and vacuum piping/connectors. I obtained a large vacuum shell that needed a 8 inch window - I simply bought a telescope glass blank, inexpensive glass drills and made a high voltage feed thru that was vacuum tight. Work arounds exist and can be done cheaply if one is clever.
Hope you succeed and obtain your end goals but creating micron grade vacuum systems is not easy to do without proper equipment - just no easy work-arounds.
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- Real name: Steven Whittam
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Re: Update on experiment
Well some good news
I was talking to my twin bro
And he was like oh I have a big vacuum pump for auto clarv at work and it can do 0.086 mpa
If I done conversions right it will do pressure needed and a heap more. Lol
He said it’s getting wired up next week.
So hopefully has connections that will work on my chamber and he will let me take experiment into his business to run test.
I was talking to my twin bro
And he was like oh I have a big vacuum pump for auto clarv at work and it can do 0.086 mpa
If I done conversions right it will do pressure needed and a heap more. Lol
He said it’s getting wired up next week.
So hopefully has connections that will work on my chamber and he will let me take experiment into his business to run test.