A Bunch of Failures

For posts specifically relating to fusor design, construction, and operation.
User avatar
Richard Hull
Moderator
Posts: 14976
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: A Bunch of Failures

Post by Richard Hull »

Direct drive oil is direct drive oil and as long as your Robinair oil is fresh from the jug it will suffice until your 19 oil arrives. Try it and see what pressure you hit at the inlet of the pump.

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
ian_krase
Posts: 636
Joined: Mon Nov 28, 2016 2:48 am
Real name: Ian Krase

Re: A Bunch of Failures

Post by ian_krase »

There is one difference: Pfeiffer pumps use moderately higher viscosity oil. I doubt it matters.
Bruce Meagher
Posts: 148
Joined: Thu May 12, 2011 11:25 pm
Real name: Bruce Meagher
Location: San Diego

Re: A Bunch of Failures

Post by Bruce Meagher »

I’d worry more about the vapor pressure of the cheap oil and the implications of using it in your newly purchased pump.
User avatar
Dennis P Brown
Posts: 3147
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: A Bunch of Failures

Post by Dennis P Brown »

As long as you are prepared to properly clean out the pump - remember, that is no simple task to really remove the wrong oil if its vapor pressure may be a future issue - then fine. The oil will provide the pump lubrication to enable you top test its operation. However, might be easier in the long run to just wait and use the proper oil; certainly less work.
User avatar
Richard Hull
Moderator
Posts: 14976
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: A Bunch of Failures

Post by Richard Hull »

It will pump or it will not pump regardless of oil. This is not a new pump. Remember it was bought from a guy who shipped it with oil in it. Not a real vacuum head who owned it last. No good vacuum head ships a pump full of 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
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

I've ordered the proper Ultragrade 19 oil from Amazon and it's estimated to get here Wednesday at the soonest. I currently plan to wait until it arrive, but I'll let you know if I decide to test it out with Robinair's premium oil.
Youngest person to build a fusor
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

The oil arrived today and I filled the pump up to it's max value (I added a tad bit too much at first). I then turned the pump on and gave it 10 minutes to pump down. I came back to the same results I received without oil: 500 microns. So, in preparation for another test I added more Teflon tape to my adapter and tightened it until I was confident it was sealed. I've also been letting the pump sit for a bit so the oil can flow into the gears and such. If anyone has any suggestions as to things I should do before testing again they would be much appreciated. Thanks!
Youngest person to build a fusor
Bruce Meagher
Posts: 148
Joined: Thu May 12, 2011 11:25 pm
Real name: Bruce Meagher
Location: San Diego

Re: A Bunch of Failures

Post by Bruce Meagher »

Try running with gas ballast open for 15 mins and then closed for an hour. Then repeat once and report for findings. Also include a pic of your test setup. Make sure you’re in a well ventilated area to protect your little lungs.
User avatar
Dennis P Brown
Posts: 3147
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: A Bunch of Failures

Post by Dennis P Brown »

Are you just pumping on the vacuum gauge? A decent pump will never pull just 500 microns; either you have a massive leak - i.e. a bad o-ring or non-vacuum tight connection between the gauge and pump body (Also, have you tried listening for a leak?) or water in the pump (so Bruce's advice will help there.)

It would help if you provided a photo of your setup with the gauge/pump connection system in detail. Also, is your pump oil now discolored? Maybe a photo of the oil level site glass.
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

Running without the gas ballast makes an awful noise. Are you sure this won't damage my pump?
Youngest person to build a fusor
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

I forgot to mention I did manage to get to 390 microns after running for 20 minutes.
Oil level
Oil level
Setup
Setup
Note: I had filled the pump up to the max marking. I lost this much oil after 1hr 10mins of combined run time (two 20 minute runs and one 30 minute run). Is this normal?

Also, I don't have access to any 1bsp parts, so I used a 3/4" X 1/2" npt adapter with plenty of Teflon tape. It seems rigged up, but O assure it's very secure. I then have a 1/2" by 1/4" npt adapter so I can attach my kf25 flange. Connecting the gauge to the kf25 flange is a 1/4" X 1/8" adapter and an 1/8" nipple because the gauge has an 1/8" female port.
Last edited by Jackson Oswalt on Sat Jan 13, 2018 1:28 pm, edited 1 time in total.
Youngest person to build a fusor
John Futter
Posts: 1848
Joined: Wed Apr 21, 2004 10:29 pm
Real name: John Futter
Contact:

Re: A Bunch of Failures

Post by John Futter »

With gas ballast closed the pump should be very quiet
openeing gas ballast will give a gurgling sound that gets louder as you open the ballast further.

put a nw25 blank directly on the pump does it go quiet without gas ballas??t.

one should not leave these pumps on gas ballast as they will loose alot of oil as mist normally half an hour is enough to clean up the oil from water ingress
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

When you say "put a nw25 blank directly on the pump" you mean on the inlet? Also, the gas ballast should or shouldn't be left on the pump? I don't know how water could be in the oil. It's fresh oil, I filled the pump up with the oil Thursday.
Youngest person to build a fusor
Tom McCarthy
Posts: 405
Joined: Wed May 08, 2013 3:36 pm
Real name: Tom McCarthy
Location: Ireland
Contact:

Re: A Bunch of Failures

Post by Tom McCarthy »

Yes, I’m pretty sure John means to put a blank directly on the inlet and see how much sound it makes.

Check out this post, fizz’s posts gives some good information on the role of the gas ballast.

viewtopic.php?f=10&t=11196&hilit=Gas+ballast

I appreciate that you’ve got new oil, but there might be something helpful there.
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

So far I've done one cycle. Afterwards I reached 370 microns and am currently doing another cycle. However, I'm not sure if that 20 micron difference is do to the gas Ballanting or the fact that the pump ran for an hour. Having a blank directly on the inlet vs my gauge being directly on the inlet has made no difference in noise.
Youngest person to build a fusor
Bruce Meagher
Posts: 148
Joined: Thu May 12, 2011 11:25 pm
Real name: Bruce Meagher
Location: San Diego

Re: A Bunch of Failures

Post by Bruce Meagher »

When you ballast the pump you only crack open the cap a turn or so. You don’t actually physically remove the cap. You appear the have 7 connections between the pump and your gauge that are possible leak sources. Is the male 1/4” NTP just above your KF-25 adapter wrapped with teflon tape (it doesn’t look it from the pic)?

To blank off the pump remove your gauge and put a KF-25 blank on your KF-25 fitting. Then there is only 3 possible leak sources. The pump should be relatively quiet when the ballast is closed and the inlet is blanked off. Does it sound different when blanked off? If so, that's a sure sign of a leak above. Post a short video with the ballast open and closed and what you think is a weird noise.

Also, it's not great to have the gauge directly line of sight to the inlet port. You should at least have a 90 degree elbow.
Tom McCarthy
Posts: 405
Joined: Wed May 08, 2013 3:36 pm
Real name: Tom McCarthy
Location: Ireland
Contact:

Re: A Bunch of Failures

Post by Tom McCarthy »

Keep it running for an hour or so, should be hot to the touch, not just warm.

My pump kept improving noticeably after each such run for the first 3 I remember, note that I was starting off at about 40 microns and got to 10, somewhat different to your situation.
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

All npt threads have Teflon tape on them. Also, I ballasted my pump with the cap completely off for 15 minutes. I then ran it for an hour and was borderline painful to touch. I have an extra 90" elbow that I plan to use, but I fear that will increase the volume of air that heads to be pumped out by quite a bit. When the ballast is closed, the pump is quite as can be. Just a light humming noise. With the ballast completely open it makes a loud gurgling noise as described by John. Currently I'm letting the pump cool off before I run it for an hour with the ballast closed. I will do this with a 90 degree elbow. Thanks for all the help so far!
Youngest person to build a fusor
Jackson Oswalt
Posts: 97
Joined: Thu Jul 13, 2017 9:10 am
Real name: Jackson Oswalt

Re: A Bunch of Failures

Post by Jackson Oswalt »

I tested it once again and only got to 430 microns with the added volume of the elbow.
Youngest person to build a fusor
Bruce Meagher
Posts: 148
Joined: Thu May 12, 2011 11:25 pm
Real name: Bruce Meagher
Location: San Diego

Re: A Bunch of Failures

Post by Bruce Meagher »

The small added volume doesn’t matter. In fact, an excellent exercise is to calculate approximately how long it should take to pump down to 100 mtorr (assuming no leaks and no outgassing). (hint: for your test system with the E2M5 the number should be less than 15 second).

You’re not reaching this level of vacuum, and you've run the pump for an extended period of time with the ballast open and closed. Therefore, imo, the most probable causes are (in what I think is the most probable order):

1) a leak.
2) contaminated vacuum gauge (e.g. oil inside)
3) contamination in the parts you installed from the inlet to the gauge
4) broken or uncalibrated gauge
5) contamination in the pump
6) pump needs rebuilding

Assuming you cleaned the parts before you assembled everything here’s a quick test to run.

Fully close the ballast port. Start the pump and record how long it takes to reach 500 mtorr. Then turn off the pump and record the pressure every 20 seconds for 10 minutes. Plot the results and report your findings.
User avatar
Dennis P Brown
Posts: 3147
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: A Bunch of Failures

Post by Dennis P Brown »

In a previous post you said:
Note: I had filled the pump up to the max marking. I lost this much oil after 1hr 10mins of combined run time (two 20 minute runs and one 30 minute run). Is this normal?
No, that is not normal! No way that much oil should be lost even if the ballast is open. I have used my pumps over five years and the oil level is about the same as when I started five years ago - also, I have purged via the ballast twice in the period. Again, no significant oil lost. Unless a seal is leaking (and oil is on the table) the only other method to lose oil is via vapor out the exhaust port or minor inflow into your vacuum system. If this was a one time only, maybe a mistake. If it has continued, that issue will cause major problems and indicate something is very, very wrong.

I am suspicious of the connection you are using for the vacuum gauge detector. Those are really for refrigerator service and may or may not be useful for low micron range. Also, you have a lot of couplings any/all could have leaks.

A major air leak will cause large oil loss from the pump out the exhaust port via a oil mist - is that occurring out your exhaust port when the pump is running?
User avatar
Richard Hull
Moderator
Posts: 14976
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: A Bunch of Failures

Post by Richard Hull »

I feel that a general comment is due here. You have had more problems than one might imagine related to just arriving at even a very crude and worthless vacuum level. This is virtually unheard of in these forums. Can you trust your gauge? We do not know. Do you have a good pump, at last? We do not know. If you have a leak, it is one of the most gross one might imagine in the world of vacuum. This, we also do not know.

Do you have a friend, a teacher, a professor or anyone with a vacuum system in your area that might be able to determine what component you have that is either working or defective? If you can't think of any, search them out.

This thread is one of the best and most completely documented abject failures to obtain even a gross technical vacuum level via repeated failures of gear or technique. I commend the effort by yourself to obtain good gear in good faith and all here who have assisted you in your effort.

It is time to take the bull by the horns and either get someone on site with you or have you take your gauge and pump to someone competent and capable of testing your pump and your gauge, separately. Treat each item as a separate entity. A good , helpful refrigeration shop might be an option. Yes, their stuff is crap by our standards, but is far better at hitting a known vacuum level than you seem to be able to achieve. If they find your pump is terrible, make sure to get them to test you gauge on their gear. No one will ever get anything done in vacuum technology without a reliable and accurate gauge.

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
Post Reply

Return to “Fusor Construction & Operation (& FAQs)”