Fusor Forums

I managed to rig up an adapter. Unfortunately, it takes the inlet down to a 1/4" at one point, so I still plan to replace it do to how much that will bottleneck the pump. The second problem is the oil. The people who sold me the pump weren't quite the brightest and decided to leave the oil in the pump while shipping it despite what I told them. As you would expect, the box arrived on my porch covered in oil. As far as I can tell, all the oil drained out. Would it be okay to use some of my Robinair pump oil with the Edwards pump? It's fresh, but it might not be compatible. As far as it's "type" (such as hydrocarbon), it doesn't say. Here's the link to it: https://www.amazon.com/gp/product/B000X ... UTF8&psc=1.
Thanks!

-JO

you can get the right ultra grade 19 oil here
http://www.pchemlabs.com/product.asp?pid=1438

Not long ago I ran the pump for about 3 minutes and got down to 500 microns (that's with little oil and npt threads). I was shocked at how quiet it is and the pressure it reached quickly. Definitely an upgrade from my HVAC pump.

While 500 microns is terrible for a good pump, that it had little oil can explain that figure but also, an excellent way to destroy the pump. Always fill the pump to the correct level before operation.

I understand this, but I won't have any proper oil for it for at least another 10 days. I need to get some tests done, so I asked if I could use the robin air oil. I understand it's not the official oil, but it would only be temporary. Does anybody know for a fact it would be acceptable to use the robin air oil? Thanks!

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

There is one difference: Pfeiffer pumps use moderately higher viscosity oil. I doubt it matters.

I’d worry more about the vapor pressure of the cheap oil and the implications of using it in your newly purchased pump.

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.

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

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.

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!

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.

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.

Running without the gas ballast makes an awful noise. Are you sure this won't damage my pump?

I forgot to mention I did manage to get to 390 microns after running for 20 minutes.
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.

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

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.

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.

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.

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.

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.

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!

I tested it once again and only got to 430 microns with the added volume of the elbow.

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.