Dual 2 Stage 4CFM 1/3HP Rotary Vane Deep Vacuum Pump - any good

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VotTak

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Jan 4, 2015
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214
Location
Staten Island, NY, USA
Hi,
I'm looking for vacuum pump for stabilization process. Never had one before. Found bunch of these on ebay: "Dual 2 Stage 4CFM 1/3HP Rotary Vane Deep Vacuum Pump".
In specification:
Weight: 17.6 LBS
Pumping Rate: 4 CFM
Ultimate Pressure: 5 Pa
Oil Capacity: 330ml
Rating Speed: 3520
Power: 1/3 HP
Material: Aluminum Casing
Package Size: 14.6" X 11.8" X 7.1"
Package Included: 1x 4CFM 2 Stage Vacuum Pump, 2x Free Bottle Of Vacuum Oil, 1x Instruction.
On similar model I also found this:
Ultimate Vacuum 0.3Pa (10-6 BAR)

Does it make sense to buy it? it is for about $90. Single stage is about $50-55
Thanks
 
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Without a link but based on the description, this is just a cheap Chinese pump. Caveat Emptor! The issue is if you have a problem, you may or may not be able to get help and get warranty service. I would stick with a brand name of some kind. Myself, I would be looking at a used US made pump for similar money.
 
You are right. That is probably Chinese pump. A lot of them are on ebay. And I'm sure that if it goes down than I might not have a chance to restore it to working order.
My idea was that at least for some time it will work. On another hand buying used JB is possible(probably from ebay) but in this case I will most definitely end up with necessity to restore it to normal condition, and having no experience in that field might be costly...
Oh... well... choices....
 
It is ABSOLUTELY a Chinese pump. No doubt about it. There are only a couple of US manufacturers of vacuum pumps. You will not have any need to restore a JB pump. They either work or they don't. If they state it is working, then nothing needs to be done. If they state it is not working and you can get it cheap enough, it is easy to repair. I just had a customer who bought one from an estate auction. He got it for $10 or so. It would not pull vac. He called me and did not know how to fix it so I had him send it to me. For $50 in parts, I got it back to perfect condition and shipped it back to him. If you did get one and needed help, I would be happy to do the same for you.

Then again, if you are looking for new on a budget, I would steer you towards a Robinair 15310. You can get one on Amazon.com right now for $113 delivered. It is still a Chinese pump but is backed by a reputable US company. It is a 3 cfm single stage. Don't get caught up in the two stage vs. single stage issue. A single stage will pull a deeper vacuum than any chamber out there can give you and you will not get any advantages with 2 stage. The Robinair 15310 is rated at 75 microns. A 2 stage pump will be rated at around 25 microns. Most chambers, unless you spend a LOT of money for scientific equipment, will not go below 100 microns. Most will not even go below 500 microns. Sounds like a big difference but considering atmospheric pressure at sea level is 760,000 microns, it is not much difference. Here is the breakdown in % of vacuum:

500 microns 99.9342% vac
100 microns 99.9868% vac
75 microns 99.9901% vac
25 microns 99.9967% vac

In other words, a good single stage pump is capable of a 99.9901% vacuum while a good 2 stage pump is capable of a 99.9967% vacuum. A very well built chamber is only capable of 99.9342% vacuum due to air passage through the chamber walls and hoses themselves at deep vac!

Moral of the story, buy a decent quality single stage with a good warranty behind it before dumping money into a no name 2 stage that you will not get any extra benefit out of!
 
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