Vacuum pump UNSTUCK -- and question

According to Ignoramus1088 :

The gurgling sound is normal until you get far enough down in pressure so you don't get noticeable bubbles with every rotation.

What kind of oil did you use? Real high-vacuum oil is designed to prevent outgassing. Compressor oil is *not*, nor are most other oils. There is a reason for high vacuum oil costing as much as it does.

As above -- the gurgling sound is normal. With a good tight seal, and not too much volume to evacuate, the sound would be about like this:

"GLORP, Glorp, glorp, GURGLE, Gurgle, gurgle, tick, tick tick, murmur, murmur ... murmur"

The larger the volume to be evacuated, the longer the Glorps and Gurgles will go on, and if there are leaks, you may *never* get past the gurgle stage.

The sounds above are from belt driven pumps. With your direct coupling, they may differ a bit, or get masked by the motor sounds.

Enjoy, DoN.

Yeah, what he said... I have a similar mechanical pump that I take to classrooms to demo some basic vacuum science (extiguishing a candle, boiling water at room temperature, silencing a bell, etc.) Fact is, the sound of the vacuum pump just about steals the show (well that and the gigantic marshmallows).

Go ahead and measure the vacuum, but it sounds like you fixed it. A stuck vane would actually inhibit the gurgling sound.

- Bruce

snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote in news:43137$43eecfb9$48f4e632 $ snipped-for-privacy@msgid.meganewsservers.com:

I am using real vacuum pump oil from McMaster.

That's nice to know. Thanks Don.

My pump is not that loud actually.

Thanks Bruce. I will try to fit a gauge and a tank to this pump. I changed my mind and will not add a vacuum switch, instead I will run the pump continuously during periods when I need vacuum available. I think that restarting this pump and leaving it turned off against vacuum would create trouble, such as sucking oil into the vacuumed area etc.

After I am done using the pump, I would refill the vacuum tank with air.

As others have posted, the noise sounds normal for that type of pump. Actually, I am used to Kinney and Stokes pumps, and they both have this very loud knocking sound when they are at high vacuum, due to the lack of any air cushioning on the valves. Standing next to a large Stokes is frightening to someone not used to it, it sounds like an engine about to throw a rod!

I have the smallest Kinney for my home use, a KC-5 and really love it. I can have it running in the garage and tell when I am at a good vacuum from inside the house.

The gurgling will come back when you use the gas ballast valve (if your pump has one), but will quit and return to the knocking almost instantly if you are at a good vacuum.

Dennis

Thanks Dennis. It seems a though the noise is indeed fully normal. What do you think about tiny bubbles in oil? I am hoping that this id due to the "break in" period when oil penetrates areas that were occupied by air (remember, I drained the pump fully), but maybe I am wrong.

Some of the bubbling may be from water vapor in the oil/off the inside of the pump surfaces. Goes away when the pump is run long enough to throughly warm it up and clear that out. If you're not running it for long periods, may never go away, but won't be much of an issue.

Glad you fixed it. I suspect the gurgling and foaming are quite normal. My pump makes a really cool gurgling noise which is loudest when large volumes of air are being pumped. Large volumes of air passing through the pump (i.e., if you're running the pump with the inlet open) may well cause the oil to foam as the air exits through the flap valve.

If you haven't already found it, check out Sam's Vacuum FAQ. This is the bible of vacuum pumps:

Chris

Thanks. I will run it for a day or so. I think that you are right about residual moisture. I would rather get rid of it.

Gas ballast, Thats the word I was looking for through this whole thread. I worked on a lot of Sargent Welch pumps at UNM and was trying to bring up the idea that maybe his was open. Getting old is hell first your memory goes, etc. :-) ...lew...

"Lew Hartswick" wrote: (clip) Getting old is hell first your memory goes, etc. :-) ^^^^^^^^^^^^^^^^ This is a true story: I was servicing machines in a shop where most of the help was female. I made the usual wisecrack, "Two things go with age. The first is memory, and the second... I can't remember." Everyone laughed, except this one quite attractive, young blonde lady. I turned to start my work again, and she got this impatient, disgusted look on her face, and said, "Well, what *is* it?"