Vacuum problems

Hey guys! I love this site. I am coming here for some help. I’ve been stuck at this all day.

I am running a China made thin film distillation that has been going really well until today.

For some reason my vacuum won’t pull low enough to distill. I’m usually at 1.5e1-5.6e1 pa but for some reason today I can only get to 2.2e2 pa. I already flushed the vacuum oil and that made it go a little

lower I was originally at 5.5e2 pa. any tips on how to fix my vacuum?

I am pretty positive that I don’t have any leaks anywhere. I took it apart and put it back together and made sure that it was sealed.

I was able to briefly go to 8.1e1 but then it went back up.

I also uploaded a picture of the vacuum.

Thanks for any tips in advance.

I’m not familiar with this pump, but maybe a rebuild kit. The old seals and gaskets could just be bad.

Compair your vaccum pump + sensor reading against your wfe+pump+ sensor. Verify that you have no leaks. If you have leaks helium leak test to find them. If you have no leaks you could try flushing your pump /rebuilding it. If that fails to reduce your vaccum level I’m stumped. If rebuild is no go, time for another pump?

what he ^^^ said.

restated: remove everything but the pump and the gauge. check vacuum. if it looks good, then it’s a leak somewhere else. use helium to figure out where.

@plant2pipe posted on the subject.

Progress on vacuum chamber build - helium leak detection, custom flanges

if it’s your pump, repair or replace it.


The first thing I do that generally clears a vacuum problem for my rig like that is to disconnect the rig from the vacuum and open the valves wide open and run the pump like that wide open for several minutes. This for me means that fresh air is flushing the system all the way from the barb fitting down the stainless bellows and such to the pump. In fact doing this is so effective at maintaining deep vacuum in my Edwards EM 28 that I only rarely now ever need to change the oil. I do change it because rate of pull down changes as the oil slowly gets contaminated but before learning this technique I could not get the pump to pull down to blank off value repeatably and reliably.

Now I routinely hit the vent valve during process and flush the system with fresh air for thirty seconds or so during the run. Probably three or four times especially on first pass crude. A gas ballast does not do the same thing at all though its function is also to help keep gas out of the oil. I do not use the ballast at all. Too damn noisy and not meant for terpenes really but more for like water vapor in a freeze dryer application. My pump needs copious amounts of fresh air once in a while to blow all that stuff through.

Assuming all seals are intact your problem points to contamination really. If you take that vac pump apart you may find a lot of sludge has built up. In fact, I would put money on it if you have never opened it up and cleaned it out before. As a suggestion consider if you do not already do it incorporating as many fresh air flushes into your own process as possible. A gas ballast on the pump can help pass the gas through but a high volumn fresh air flush will evap condensed vapor in the lines and flush them into the pump oil which is simple to change on my pump. I do not use my gas ballast open because those are really meant for high vapor loads like water in a freeze drying operation and not trace terpenes in a distillation.


Turns out I def had a leak. Working on fixing that now.

Thanks for the input fellas.

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Sweet, glad you got it figured!

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anyone seen a ‘chipped’ rotor on a vac pump? its not on the edges near the retainer ring or near the vanes but in the center literally against the back end plate. almost looks like a contaminate or something got between the rotor and the wall and something rubbed away at it causing a tiny hole about the size of a needle head. and i can see light ware in the rotor itself from spinning around… not something that comes with repair kits…specifically talking about a welch 1400

Is it the vane that has the hole or the rotor?

This is called a major rebuild, not the common seal replacement kit.
Give these folks a call if you have any persistent problems, they can get what you want specifically for your welch 1400.

I have started a new topic as you have seen,

@xsh0rty did you notice @Soxhlet linked you to exploded diagrams of many if not all relevant welch pumps, not just the seal kit?

Edit: and now there is a link to @xsh0rty’s other thread

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If you have a chipped vane (it happens but not frequently) that can be repaired/replaced by qualified people. If you haven’t resolved your pump issues, you can send it to us for credit against a new pump packaged for Oil extraction.

How about a chipped scroll?

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