Bell and whistles diffusion pump based vacuum system.

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Richard Hull
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

Varying odd ball OEM flanges and multiple "in country standards" will forever seem to force a lot of less well equipped amateur scientists with limited funds to adapt pieces of vacuum gear to mate with other surplus vacuum items. There are many good deals to be had surplus on the market. However, with no machining or welding skills, the average amateur is forced to pay machine shops to do what they cannot. This can sour a good deal bought for a great price to the point that it is no longer such a good deal. The two type flange adapters of more or less different, yet, "standard flanges", can solve some issues, but the adapters can cost a good bit of cash, themselves. This is most unfortunate for the more impoverished and unskilled young vacuum system assembler.

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
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Dennis P Brown
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Dennis P Brown »

As a physics major in college (again, long ago), I was expected to go to the main machine shop and get guidence on machining the base plate and adapters for experimential equipment I needed.
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Maciek Szymanski
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Wiring the control panel

Post by Maciek Szymanski »

I’d like to have a fully manual control panel for the system. The panel will serve also as the switchboard for other equipment. All the component come or either from a dumpster or are bought cheaply from the army surplus. The most expensive part was the textolite board on which the whole thing is assembled.

Artem Artemow I think you should like the style ;-)

AC9C75EB-8A5B-43F2-85E7-036A9B0B2F0F.jpeg
The control panel installed on the trolley. The big rotary switch is the main isolation switch. Below are the fuses and main pilot lamp. The row of small rocker switches controls all the solenoid valves valves and the water circulation pump. Pilot lamps below the switches indicate the operation of valves equipped with position contacts. The big 3 phase switch with removed housing is for rotary vane pump and the rotary switch right to it is for the diffusion pump. The four mains sockets are for vacuum gauges and other experiment related equipment. The four pole socket is for rotary dump. Still not installed are multi pole sockets for valves.

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Wiring the panel on the backside.

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The 3 phase motor switch with electromagnetic overload protection.

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Machining of the capacitor bracket. For the solenoid valves there must be a supply of 220V pulste to activate the valve. This will be done by a bank of electrolytic capacitors charged to 220V when the valves are closed. This small textilste bridge will hold them on the backside of the panel.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Dennis P Brown
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Dennis P Brown »

Talk about 'classic' controls! Right out of a 1930's Sci-Fi movie. Nice. While I used relays and push buttons in my orginal, there is something both 'classic build' and pleasent aspect to a control pannel with those manual controls (and just like in in Star Treck, going to "manual override" which their last effort against the computers, you can too ... ;) )
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Artem Artemov
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Artem Artemov »

A lot of retro. Haven't seen these things in a while.

The three-phase switch is very similar to the Soviet АП50Б. It was given to me when I was a child. All these parts have a huge margin of reliability. The Chinese switches I want to use can't boast of this. Not enough big arrow meters! )
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Maciek Szymanski
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

The switch is indeed Soviet production АП50. As for the needle meters - they will come with the vacuum metering system and the HV supplies.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

The panel wiring is finished. Today I’ve tested some valves.


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“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Dennis P Brown »

Proffesional wiring work; pictures appear very circa 1950's! Especially that type of wiring in your earlier color pic of a panel. The black and white pic's really adds to that sense. Today seems like through back Friday on posts.
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Richard Hull
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

The cable lacing is a very military WWII touch. Today, coiled plastic tube seathing is used or nylon zip ties. Nice work.

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
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

I’ve finally come back to my vacuum system.

I’ve installed the rotary vacuum pump:

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Unitra BL8 rotary vane pump. This is two stage oil rotary vane pump with the gas ballast valve. It is belt driven by 3 phase motor. On the vacuum port of the pump there is installed the oil trap ant the manual isolation/vent valve. According to the catalogue the pumping speed is 6,7 m3/s at 1 Torr and the ultimate pressure 5e-4 Torr

The control panel is finished, with sockets for the control valves and the 24V transformer:
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The water cooling hoses and the coolant tank for the diffusion pump:
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As the low vacuum metering system I’m using Unitra PN21 double channel analogue pirani gauge. The unit was overhauled and calibrated with a good Leybold metering system at my work. Here is the control unit, the pirani head and connecting cable. The small cover on the right side of the instrument covers the calibration potentiometers.
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Today I’ve pumped the system with the rotary pump only. There was no chamber - the system was closed at the gate valve CF100 port with a reduction ring and a viewport. So the pumped volume included the diff pump, the cooled baffle, the gate valve body, , the vacuum canister, control valves, and the rubber vacuum hose. I was able to get it down below 25 microns in about 15 minutes:
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I’m quite happy with it, especially that I’ve not changed the vacuum pump oil - I want to run it some time with the old oil before I replace it, as the pump was quite long in the storage. I hope for better figures with new oil. The control system need some minor improvements, like adding an extra pulse capacitor for the gate valve - the current one is on the limit, an sometimes the valve fails to open.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Richard Hull
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

I have always recommended running with old oil in a pump, (provided a small drained cup full is not just dark gummy soup). The old oil, if it has covered things up well should be run for over an hour until the pump is hot. In this manner all the seals and walls will have a chance to circulate and get any crud and glop off the walls and partially polish the vanes and their springs. If what comes out is nasty then you have done good and will not totally waste a first run of clean oil. If what comes out is relatively dark but clean then so much the better.

Your first run with old oil from storage was really quite good! Fresh oil may win you a clean and nice running pump. Great work on the foreline pump setup.

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
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Maciek Szymanski
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

Today I’ve made some minor improvements to the system - I’m hoping to test the diffusion pump tomorrow. But for today I’ve celebrated by making a little bit of plasma:


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“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Richard Hull
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

Please run the plasma again. Report the voltage, the pressure and the current and you will be the first human being to make the new plasma club!! The rules say to must report those three variables. You have already supplied the required images. Fabulous images!

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
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

Richard! I don’t think it’s worth the plasma club - I’ve done it mainly to test the micrometric valve I’ve rebuilt some time ago. Ad as I had In hand a random feed through and a power supply from an ancient photocopier (5kV and very current limited due to selenium rectifier stack based voltage doubler) I just put a soft soldered “grid” inside to make nice plasma photos.
I’m building much more serious power supply based on the breakdown tester transformer. Then I’m going to do some experiments with electron current measurements.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Those damn switches

Post by Maciek Szymanski »

For controlling the solenoid valves I’ve used old Russian ТП1-2 rocker switches. They are rated 2 amps. But apparently the transient currents of those big electromagnets overloaded them, and two has failed. Today I’ve replaced the three switches with standard Chinese ones - 10 amps rated. Two failed immediately. Third failed after one successful switching.
I hope that the 5A rated Russian switches will be reliable enough...
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

Whatever you think is right for you Maciek. I am still looking for a first in the Plasma club. I am glad we strengthened the requirement to exclude DIY mason jar demon system, "quick dabbles". Strong wins here means a stronger cadre of contributors.

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
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

I’ve finally replaced the faulty switches with the 5A old stock Russian ones. And today I’ve started the diffusion pump for the first time. It worked seamlessly pumping the chamber (the gate valve body blanked with a 100mm flange and a viewport) down below 1 micron in less than minute. But I was surprised how quickly the coolant heats up. I have a 20 liter plastic tank filled with the -35°C rated car antifreeze diluted 1:1 with water. After 40 minutes of operation the tank was significantly warmer. I’ve to put a thermometer into the tank and monitor the temperature.
The ionization gauge has measured 1.5e-7 Torr, but I do not trust this figure. The calibration potentiometers seems to be dirty, making the adjustments a bit sloppy and I’ve to recheck the base voltage and current of the gauge. For other hand I trust my pirani gauge, so the it was surely below 1 micron.


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The pump system with the diffusion pump working. The dark liquid in the tank is the diluted car antifreeze. For circulation I’m using a sunkable 24V camper faucet pump.


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The glass Bayard–Alpert ionization sensor with KF25 flange.


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The diffusion pump illuminated by the Bayard–Alpert glowing filament.


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The low and high vacuum gauges. The top unit is PN21 double pirani showing clearly pressure below 1e-3 Torr. The lower unit is PW11 ionization gauge set in the logarithmic range, showing suspectable 1.5e-7 Torr.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Nikodem Czechowski »

Nice results, although indeed the 1.5e-7 seems to be suspiciously low. Do you have fresh oil the diff pump?
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Maciek Szymanski
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

The oil is fresh DC704 and the whole system is cleaned and overhauled. I don’t believe this ultimate pressure, it seem to me as gauge fault. I’m using very similar system at work (same pumps and valves) and it routinely pumps down to 1e-6 mBar (7.5e-7 Torr) but it takes a bit longer.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Finn Hammer »

Maciek,

This is a good thread, which I have just read from start to finish.
Very usefull for me.
During the testing of my vacuum station, I had already noticed that a turbo takes forever to come to a halt at E-3 Torr, and bringing it down faster by increasing the pressure is, although possible, inelegant.
Your design with the many valves, and in particular the vacuum holding vessel in the foreline is better, I will copy it.
Back to the drawing board.
Thanks!

Cheers, Finn Hammer
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

This is, indeed and wonderful system. Unfortunately many folks can't afford all the valves. Back in 2004 I bought 4 Varian fully rebuilt 2.75 conflat bellows valves from Duniway for $1000. While expensive, they have worked and still work well in my system. Money well spent. Good multiple valving allows for a very versatile vacuum system.

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
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Dennis P Brown »

Good you change the oil. While the vacuum gauge might be off under very low pressure, a good diffusion pump and clean system can bottom-out 10-6 torr.
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Maciek Szymanski »

It's gerat that you found this thread useful Finn! The problem with long spinning turbos is really annoying but at last they start up immediately - the diff pumps need both start up and shutdown time. At my work in the laser laboratory we have two chambers - one is the interaction chamber and the other is te optical compressor. The interaction chamber needs to be vented and opened regularly, so the turbo is equipped with the the gate valve and large forevacuum volume so there is no problem to keep it spinning while doing work at the chamber. For other hand the compressor needs the attention rarely so there is only a very simple pump system. Bu sometimes in the alignment work we need to vent and pump the compressor quickly. Then only way to spinn down the turbo in a reasonable time is careful operation of the manual vent valve (with a restrictor) while listening to the whizz of the rotor. Quite terrifying experience.
“Begin at the beginning," the King said, very gravely, "and go on till you come to the end: then stop.” ― Lewis Carroll, Alice in Wonderland
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Richard Hull »

I have tried slowing down the turbo by venting and even with gentle slowing was also horrified and worried for the pump. I will never attempt it again. At 75 years of age I figure I have the time to be off doing something else useful and constructive as the device slows naturally to a stop.

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
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Joe Gayo
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Re: Bell and whistles diffusion pump based vacuum system.

Post by Joe Gayo »

Slow spin down can actually create more wear on turbos. As they pass through resonances the bearings see more stress and if they dwell in these conditions it can shorten life. Most high-quality turbos have a vent port and recommend use with an orifice. I vent using dry nitrogen and a 10sccm orifice (in sonic flow) and it quickly spins down the turbo and then once the rotation is essentially stopped, I bypass the orifice and directly vent dry nitrogen into the chamber.
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