Trouble with new Trivac D2A Leybold-Heraeus

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Alex Kahn
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Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Hello all,


After I decided not to pursue the restoration of my heavily corroded Edwards E2 just yesterday I found a very nice looking and beautiful running Trivac D2 from Leybold-Heraeus.

The only problem is that it will not establish a vacuum.
Running since one hour. Pump is getting warm. New oil filled up according to manual. 200 micron max is what I read with or without gasballast…

Any advice where I should look first?
I think a couple of members here have a Trivac as well.
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Rich Feldman
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Rich Feldman »

Nice looking pump you got there. (bit surprised that forum accepts 3.7 MiB images these days)
Are you sure the micron gauge is accurate?
Can you adapt gauge directly to the pump port? I recall reading something, long ago, about gas permeation in thin hoses made for convenient HVAC service rigs.
All models are wrong; some models are useful. -- George Box
Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Yes I’m sure the gauge is correct. Tested with another pump. Works ok.

And the HVAC rig is solid as well. New sealings, new hoses and high quality from Refco. Cheap Chinese ones are sometime leaking.

Well pump is running and degassing now since a couple of hours. 70 degrees C now and achieved slowly slowly 130 microns.

I suspect some valve stuck or blocked or something….. 😃
Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Here some more pictures. I achieved 90 microns today and then I switched off my the pump. No chance to get below…

A bit of oil is coming out of the ballast valve which seem to have no effect when I turn the knob. That’s all with my observation so far….




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Richard Hull
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Richard Hull »

Oil is filled with bubbles and looks discolored through sight glass. You have a leak in the connections or lines. The only way to determine a pump's worth is to have the gauge attached at the head, no hoses and their connections allowed. This assumes you want to know about the pump and not how good or leaky your hose and adapter connections are.

Did you flush the oil with a flushing oil. Sometimes it takes a minimum of three changes of oil to get the bulk of the last owner's neglect and abuse out of a pump. Discolored oil is defective oil and bubbles in the sight class after a long run is a sure sign of leaks in a line or bad seals in 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
Aleksa Djokic
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Aleksa Djokic »

These pumps are know to have a really crude mechanism of retaining the vacuum when the pump is off. When the pump is running, on the back side, where the motor coupler is, there is a centrifugal switch that closes a plunger when the motor spins, that plunger tends to stiffen a lot with age and heat, replacing it or lubricating it can and will improve the vacuum. When the pump turns off, this plunger opens the hole and lets air in, there is another plunger that closes of the intake flange and prevents leaks and oil to start leaking in to the system. Newer models have a electric solenoid valve for this feature.
Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Thank you very much for the assessment, much appreciated.


In this case I will focus first at these plungers or valves. I read about them and could hear a plucking sound in the moment I switch off the pump.

Especially these bubbles in the new oil could be explained with a probable leak somewhere here at the mechanism. Pump was oilchanged before btw but not flushed.

Before I order the maintenance kit for the pump I will go this way. I hope I can reach the centrifugal switch from outside with detached motor. The intake assembly looks like attached with two bolts only.

It’s a beautiful pump and cost just 70€ so I’m ok with a 200€ bill for the maintenance kit.
Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Ankriegt! Disassembled.

Found some suspicious details already.
Wonder if the away corroded tongues of this valve like mechanism could be the cause…
The nozzle from this pressure relief mechanism will receive some polishing as well. To be continued.


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Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

After washing and cleaning a quick inspection revealed damages on some surfaces. Also black high temperature signs close to the rotor casing. Scratches in the casings and on the rotor. Corrosion on several internal parts.

Also one single vane seem to have a damaged to edge.

I think the way forward is some polishing and egalisation.
Also the rotor could be slightly polished.
Then hope the best and assemble with new parts.

Any thoughts here?


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Richard Hull
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Richard Hull »

This pump was not cared for at all! The corrosion is pure water damage. It has had a hard life in the hands of a person who didn't care for his pump.
I have no hints beyond if it were my pump, I would toss it. You may wish to fight it, and you may win with enough money.

The pump I use with fusor V was free at a hamfest in 1999. It was seized up. ( A 5 CFM Precision, belt drive pump).
I have told the story of just how I used a hammer on the large belt pulley to free it up. I used flushing fluid for three fillings and then a good pump oil rated for belt drives to get 5 microns. I have never and will never take it apart. It has been in my fully assembled fusor vacuum system since 2000. It has not seen air as I have it valved off at both the exhaust and intake. It has served fusor II, III, IV and now fusor V for 23 years. My oil log shows I changed the oil only 3 times since 2000. Last change was 2015. I guess I ought to get to changing it again. Still pulls well below 10 microns in under 3 minutes through 6 inches of India gum rubber hose to the foreline valve which isolates it from the turbo.. I think the secret is never moving, touching or allowing the pump to breath outside air. It only has a path to air when I change oil. It has spent most of its life doing nothing! It might run 25-30 hours each year.

By any standard, I should have changed the oil much more frequently. The secret is it is sealed against all air since 2000. It is effectively stored in my sealed system which suffers temperature gradients, (extremes) of about 6 deg F. to about 100 deg F in my unheated lab.

The upshot is, one need not fawn over their pump just as they should not abuse it. Constantly opening the pump to air, even at the exhaust, allows moisture into the pump. Serious vacuum techs, do not move, disconnect or toy with their mechanical pumps but leave them in a sealed system, valved against air when not running.

Once you have a good, verified, mechanical pump, lock it into a system if you are serious about not having to constantly fawn over it. Whoever owned your pump used it to pump God knows what, often against an outside air load with associated moisture and when done threw it into some corner of a workshop open to air. Sad...

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
Aleksa Djokic
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Aleksa Djokic »

Definitely polish the walls and be careful when sanding the rotor plates, make sure not to lose the factory curve. Also, be very careful when assembling it back, use a torque wrench. The gap between the rotor drum and the stator walls has a very tight tolerance, this is the oil seal that separates the intake and exhaust. The stator cylinders have surface ground sealing faces, be careful not to damage them. As soon as I saw the centrifugal plunger my skin crawled...What a terrible design from leybold.
Alex Kahn
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Alex Kahn »

Toss it? Was too late. Ordered the maintenance kit beforehand. Next time I wait until I checked what I got. This pump was in really bad shape. Wouldn’t expect it but pretty outside is not enough.

I cleaned and finished some surfaces and also tried to remove defect and scratches as good as I can.

23 microns was the best I could achieve. Pump had to run in a couple of hours first. But after a while it was getting better.

Would have hoped to see 2.3 microns but 23 is ok at least for my new ac unit… 😃


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Richard Hull
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Richard Hull »

A bit of effort and money for a slight improvement.
Some pumps, especially mistreated ones are just shot if you plan or pray for single digit micron vacuums at the head. 23 microns at a diff pump or a turbo pump will play fusion. It is just we like to go as low as such a pump might promise when well kept by its previous owner. On a used pump, 10 microns at the head is a big win. Any lower on a used pump is gravy and dressing on the meat.

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
Aleksa Djokic
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Re: Trouble with new Trivac D2A Leybold-Heraeus

Post by Aleksa Djokic »

Its looking promising! I would suggest not touching it anymore until it shows sines that it needs a repair kit. The vacuum of 23 microns is very good, you do not need better then that. After some time, it will probably get even better, use the gas ballast to degas/dry the new oil. From my experience, with that exact model, 23 microns is more then good.
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