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Author: Subject: easy way to save your vacuum pump
Rogeryermaw
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[*] posted on 18-6-2014 at 10:16
easy way to save your vacuum pump


i have been playing with this idea for a while and i think i'm going to put it into use this weekend. i'm curious if anyone has any ideas or advice to make this better, safer bla bla bla.

one can acquire empty "freon" bottles from a/c shops and salvage yards for next to nothing...absolutely nothing in many cases. my intent is to grab 2 or 3 of these...perhaps more and plumb them together with a tee fitting on the last bottle. open all valves and pull vacuum on the bottles. close the valve at the vacuum pump and then i have a fairly large space (in cu. ft.) with deep enough vacuum to run most distillation work without having to evacuate the cylinders any further and no corrosive or flammable vapors get into my pump. when my work is finished, i can wash the cylinders with water, dry, re-evacuate and good to go for the next run.
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thesmug
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[*] posted on 18-6-2014 at 10:18


Seems simple enough but are you sure the cans can withstand vacuum? Do you have pictures of the types of cans you are using? It might also be a good idea to put something like activated carbon in the cans to absorb gasses and vapors.



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Rogeryermaw
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[*] posted on 18-6-2014 at 10:30


i am certain they can withstand vacuum as vacuum is applied at the factory when these cylinders are filled. those i have are r410 and r134 refrigerant bottles. i'm not certain if the valves can be removed to allow filling with adsorbent material but that is a good idea and one i will look into when i get home this evening.
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Organikum
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[*] posted on 18-6-2014 at 12:30


Thats common practice but it commands that your vacuum setup is sealed almost to perfection, if you asked yourself for what the often encountered intricate complicated one-piece glassware is good for: Here you go.

A strong anal personality streak comes very helpful here ;)


/ORG




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WGTR
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[*] posted on 18-6-2014 at 13:21


I do the same thing. I have a 1 cubic foot vacuum chamber with two valves; one between the pump and the chamber, and
the other between the chamber and whatever else. It's a "vacuum reservoir" essentially. I use it for filtrations, and
also for some various odd applications. I vacuum distilled white phosphorous out of a test tube reaction using this setup.
The use of vacuum allowed the isolation of P at a lower temperature than would have otherwise been possible.

There's another benefit to your idea, and that is the protection of the pump against glass breakage. If you crack your nice
Fisher two-stage rotary vane pump to atmospheric pressure, it rapidly pumps its oil out the exhaust and burns up. The bits of
broken glass and reaction components don't help either.
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Rogeryermaw
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[*] posted on 18-6-2014 at 14:56


i just was fuming away... after my divorce, i stopped caring... so when i got back on the horse and got my pump out i found it had seized. after carefully disassembling, cleaning and polishing the vanes and contact surfaces, it has a noticeable loss of performance. now i have to get a new one and i will damn sure protect my investment this time.

looked around to see if i could replace the head but haven't found anything useful yet.
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WGTR
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[*] posted on 18-6-2014 at 19:39


If you are near a Napa auto parts store, I know they sell various automotive A/C vacuum pumps. They might let you try one out. I saw a single stage one for about $200.
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Dan Vizine
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[*] posted on 2-10-2014 at 11:21


Quote: Originally posted by Rogeryermaw  
i just was fuming away... after my divorce, i stopped caring... so when i got back on the horse and got my pump out i found it had seized. after carefully disassembling, cleaning and polishing the vanes and contact surfaces, it has a noticeable loss of performance. now i have to get a new one and i will damn sure protect my investment this time.

looked around to see if i could replace the head but haven't found anything useful yet.


I have had the chance to tear down dozens of rotary vane pumps over my career, and I never saw a pump get worse from cleaning. If your pump was a substantial investment, try a rebuild kit. All the manufacturers sell them. It contains all the "consumables" and metal items that wear out, like vane springs.

You didn't use abrasives I assume? If not,I wouldn't consign that pump to the scrapyard just yet. Although all bets are off if the surfaces that the vanes sweep over were degraded. It's dead.

We had a QAD way of bringing a vacuum pump back to life that is probably only something you'd do if you absolutely needed the pump right away and the cost of solvents wasn't an issue....

We'd drain the oil, fill with DMF, do whatever it took to make the shaft turn, run it for 30 sec, drain, fill with alcohol, run it for 5 sec, drain, fill with acetone, run for 2 or 3 sec, drain, fill with PE, run for 2 -3 sec, drain, fill with oil part way, run for 5 sec, drain, refill with oil and you'd be good to go. Since the last solvent was 63-75 C PE, any left in there volatilized as the pump warmed. For an emergency fix, this off-the-wall method was quite successful, not that I'm suggesting it to anyone.


[Edited on 2-10-2014 by Dan Vizine]
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Praxichys
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[*] posted on 2-10-2014 at 11:31


I have resurrected several corroded refrigerator compressors with mild phosphoric acid solutions. Use a hacksaw to crack the case all the way around. After acid rust removal, flush with water, then hose down with WD-40. Degrease the rim with acetone on a rag and reseal case with silicone and cloth tape. Standard 30-weight motor oil will replace the tainted compressor oil, followed by running for an hour to get it hot and purge the volitiles. Works like a charm. Sure it might not be like new, maybe pumping efficiency is low, but it still gets the job done, and hey, it was free.




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Dan Vizine
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[*] posted on 2-10-2014 at 11:36


It really makes you reflect on the essential truth that necessity is the mother of invention, eh?
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