1st vacuum used pump

[mike_meridian]

I bought a refurbished 6 cfm vacuum off ebay. It claims to pull down to a 50 microns, but with no specifics. I didn't have a system to try it on so i'm just trying it out on a recovery tank. It has been about 3.5 hrs and it is down to about 378 microns, and looks like that might be as low as it goes.

Vacuum pump connected via 1/4" hose to the center of manifold, low side to recovery tank, closed the high side gauge and used hose to attach to vacuum gauge to tank liquid valve.

Does that sound like the pump is not pulling like it should?

thanks,
Mike

[Freezeking2000]

Did you change the oil?

[mike_meridian]

Yes, I put in new oil.

What I didn't do is leak check my gauges. They are pretty new, but I guess that doesn't mean there isn't a leak. I might valve it off and cut off the pump and see how many microns it looses.

Also, I didn't know how hot those pumps ran.

thanks again ,
mike

[BobbyBJr]

Also check the oil level. A little over or under does make a difference sometimes. What kind of hoses are you using? To pull a system, or a tank, down to 50 microns your hoses and fittings will have to be absolutely leak free and regular charging hoses are not. Getting down to below 400 microns is pretty good, but with leak free hoses and the proper oil, it should do better on just a tank I would think.

later,
Bobby

[dec]

what brand did you get? how long of hoses on you gauges and what kind of shape are they in? Guess I kinda cheat when I check my pump. I made a short copper line to I hook right to my vacume gauge so Im not pulling through hoses. Ok thinking of it , what type of vacume gauge are you using?

[mike_meridian]

oil level should be ok, I just filled it to the line in the window.

I have a yellow jacket digital vacuum gauge, off ebay also which I am also trying out, it seems to be doing fine. It is solid stae and works , has a calibration sticker, so i guess its ok.

I'm just using 1/4",x 36" hoses, on a little robinair manifold.

I like to copper line idea.

thanks,
mike

[BobbyBJr]

Did you fill it to the line in the window with it off? If so, it is more than likely over filled. On most of the brands I have seen, the oil level should be at the bottom of the glass when off and come up to the line when it is running. There are some other threads here about vacuum pumps if you care to do a search.

later,
Bobby

[Black Adder]

gonna have to use copper lines and not hoses to achieve that low a vacuum. No way is a hose setup and manifold going to get down that low. I can get down to about 400 with hoses no lower no matter how long you run the pump.

[travisfl]

Originally posted by Black Adder
I can get down to about 400 with hoses no lower no matter how long you run the pump. Must be leaky hoses (or more likely, the seals). If left running for a while I regularly get < 100 microns with Robinair hoses, nothing special to them.

[johnl45]

Try connecting it directly too the micron gauge.

[2hot2coolme]

Why would anyone take a chance on buying tools like that on E-bay?

[travisfl]

Price?

[beenthere]

Just see what it can do on the hoses only.

If that isn't a new recovery tank, you might not get it very low.

[Mr HVAC41]

had a vaccum pump with my old company. i dont know how old it is but it has had some running time. i got it and unbeknownst to myself, it had probably 1 year old oil in it. it was in a van that had sat @ shop probably a year. well, local dayton supply house had a luncheon and we all went. they were testing vaccum pumps. this yellow jacket pulled the micro down to 21 in about 30 seconds. they changed to oil and it did 16micros! the guy told me that this yellow jacket got 15 brand new off o da shelf. the next tech also works for this company. he put his NEW robinaire on the table. after 2 minutes, i think it did 45! the changed the oil and let the thang run 5 minutes it did 35. naturally it was his 'old pump when he ran service outta my van' type of deal. when i left the company, we swapped out the vaccum pumps and he was very happy!

[Chill]

Blank it off, and do a standing leak test. If you have a leak it will keep raising past 2000 microns or more in 5 mins. If you have moisture in the hoses it will slowly rise to 1500 microns.

[mike_meridian]

thanks again for all the replies.

Price?

I paid $160 with spipping.

Why would anyone take a chance on buying tools like that on E-bay?

Unemployed, student, hope to replace if needed when employed, I always seemed to buy used, however you still might be right I'll know next time.

I just found the instructions to the pump tonight , they were in the box under the receipt, they help out quite a bit, still i will refer to all the good info in the post also.

thanks again for your time and experience.

Mike