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Vacuum chucking Robinair 15310 set up??

R

Randy Smith

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Mar 28, 2011
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Harrisburg, PA
Hello; I am setting up a vacuum chucking system and looking at a Robinair 15310 vacuum pump. After a LOT of searching on the internet, I found a fitting to convert the 1/4" flare fitting on this pump to a standard MIP connector Flare Fittings from http://www.plumbingsupply.com/flarefittings.html near bottom.

But I still have some questions from anyone who uses this pump or ones like it.

Is an oil-less pump less hassle than a pump that takes oil? I assume so, but is it enough of a difference to make it a criteria?

Does this pump create an oil mist? Does it need a filter for this?

For vacuum chucking on the lathe is 1/4" ID tubing sufficient, or does 3/8" tubing give better results?

Is there anything I don't know that I should??

Thanks for any experience you can share....
 
Hi Randy,

Good pumps but . .

The issue is oil. I got a recon Robinair 15600 (6cfm). First time I used it it didn't take long for me to discover I was working in an oil fog. The Robinair oil bath pumps are designed to pull a constant hard vacuum with no "air" flow through the pump. Once you reduce the vacuum with a bleeder or leaky system, you allow air to be flowing through the pump. That airflow picks up and atomizes the oil lubricant. You can't prevent the atomization so you must fit the pump with an oil coalescing filter as pictured. Otherwise you'll have everything in your shop, including your respiratory track, greased. Takes a bit of plumbing as you can see from the pix. I had to actually tap the handle exhaust port to get my piping to connect.
 

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Of the three types of vacuum pumps, the rotary vane is probably the best suited for vacuum chucking because they generally offer sufficiently high flow capability and adequate vacuum level. The other two categories are diphragm pumps and piston pumps. Diaphragm pumps don't use oil in the flow path and generally have relatively lower flow and lower vacuum level, but still may be perfectly adequate for the job. Piston pumps do use oil in the flow path. Piston pumps create the highest vacuum level, but can't match the flow rate of rotary vane pumps.

Rotary vane pumps come in dry vane and lubricated vane types. Dust contaminating the oil can be a problem if not filtered adequately. That can lead to build up of crud and reduced efficiency of the pump. Because the lubrication system is open cycle they are a bit more hassle to deal with. The dry vane type pumps are more desirable for vacuum chucking, but adequate dust filtration is still important since dust is abrasive and increases wear.

If your pump is spec'ed to have an open port flow rate of 4 CFM and a blocked port vacuum of 24 in-Hg, that should be more than sufficient. In actual practice there will always be leakage at various points in the system. Having a good flow capability helps to insure that the vacuum level with leakage (and bleed) can still be set to a sufficiently high level as needed (and in accordnce with common vacuum chucking guidelines).
 
ps:

My thought is that the Robinaire is better suited for air conditioner work than it is for vacuum chucking. The Gast dry vane pump isn't generally up to pulling a hard vacuum necessary for aire conditioning work, but is excellent for vacuum chucking.
 
Vacuum volume is inversely proportional to the square of the sucking distance or smallest diameter. Translated to English: Double the distance, one fourth the volume. Half the diameter, one fourth the volume. A single 1/4" fitting in a 3/8" system will make significant changes. If you use an oiled pump, use vacuum pump oil. The vapor pressure of regular oil will compete with your pumps ability to create a vacuum.
 
Randy Smith said:
Hello; I am setting up a vacuum chucking system and looking at a Robinair 15310 vacuum pump.
Click to expand...


I decided to bite the bullet and got a used Gast vacuum pump. A friend who works on HVAC systems says they use their pumps outside, so it isn't a problem. If they have to work inside they have a special pump.

Thanks for all the suggestions and information.
 
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