Vacuum Pump

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Rockytime

Rockytime

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Arvada, CO 80003
I have blanks that need stabilizing. I can come up with a vacuum chamber but it is the pump I am wondering about. A friend gave me a Gast 1/6 HP vacuum pump. The model number is 0211. It is not oil less and I wonder if that is a problem. Also, I cannot decipher the performance charts I find on line. Most small pumps are rated in cfm. 2 cfm, 3 or 4 cfm. For this pump the specs are in psig. I don't know how to understand them. My question is, will this pump perform satisfactorily?
 

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your local air conditioning supply store will have all the pumps you want of all sizes.
The oil in the pumps seals the vanes to the pump shell and causes the vacuum to happen. With out the oil no vacuum. Good luck with it let us know how it turns out. I have never had time to give what your doing a try, but hope to one day. The day job gets in the way.
 
Rocky, just dont fire her up in a basement if you have one. I spoke to a vendor at a local wood working show in the fall last year and he told me a story about when he used his first vacuum pump and it was an oily one and he could figure out why everything in his basement had an slightly oily film. His wife happened to catch a glimpse when walking by the area when he turned the pump on from another room and low an behold there was a little puff / plume of oily smoke that came out. Now I am not certain if it was the brand or that the seals were bad or what...he just warned me to stay away from pumps that had oil.

2cents
jb
 
My understanding is all vac pumps have an issue with oil vapors. I have seen where people put an extension tube on the outlet and by doing that it gives the oil a chance to settle rather than disperse. I also have seen where people put some cloth type of material over it, not enough to block air flow, but enough to slow oil mist. I have never done either of those, so I might be wrong. :)
 
That pump is most likely not going to develop a real deep vacuum. The deeper the vacuum you can pull, the more air you can pull from the blanks and the more resin you can get back into the blanks. You have to get the air out to get the resin back in.
 
MesquiteMan said:
That pump is most likely not going to develop a real deep vacuum. The deeper the vacuum you can pull, the more air you can pull from the blanks and the more resin you can get back into the blanks. You have to get the air out to get the resin back in.[/quote

I think you may be correct. I finally found the specs on line. It is 1.1 cfm. I am assuming it is not strong enough.
Click to expand...
 
Rockytime said:
MesquiteMan said:
That pump is most likely not going to develop a real deep vacuum. The deeper the vacuum you can pull, the more air you can pull from the blanks and the more resin you can get back into the blanks. You have to get the air out to get the resin back in.[/quote

I think you may be correct. I finally found the specs on line. It is 1.1 cfm. I am assuming it is not strong enough.
Click to expand...


CFM is a volume measurement -- It tells you how much leakage you can have and pull some vacuum

inches mercury (or inches Hg) is the more common measure for how "deep" a vacuum can be pulled. I have a gage on the vacuum chamber that reads inches hg. 28 is a good number.

My bet is that you have a pump that will pull about 20 inches of vacuum or so. Will likely work well for small bowls on a vacuum chuck on the lathe.
Click to expand...
 
CFM is irrelevant as far as how deep of a vacuum the pump will pull. That just measures how fast the pump will move the air at the pump with nothing attached. Vacuum pumps have two ratings. They give the CFM rating as well as the vacuum rating. The vacuum rating is what you are interested in. Some pumps will show the vacuum in inHg (inches of mercury)and some will show it in microns. A perfect vacuum at sea level is 29.92" Hg or 0 microns. Remember, a perfect vacuum is not obtainable but we can get close. Also remember that vacuum is the measurement of the reduction of air (for our purposes) and at a perfect vacuum, you have removed all the air. The closer you can get to a perfect vacuum, the more air you can get out of your wood and thus the more resin you can get back in. For best results, a pump should be rated at 29" Hg or higher or 100 microns or lower.

Most Gast pumps I have seen are rated at 25 inHg or less. Their best one that I have seen is rated at 28" Hg which is still not as good as I would like to see and you can do much better with an oil filled rotary vane pump. Most of those are rated at 29" Hg or 75 microns or less.
 
KenV said:
I have a gage on the vacuum chamber that reads inches hg. 28 is a good number.
Click to expand...

Ken, with the utmost respect, I have to disagree with you if you are at sea level! If you are at 1,500 feet above sea level, then yes, a 28" vacuum is great. However, at sea level, a 28" vacuum is only a 93.6% vacuum. Using a rotary vane oil filled pump, at sea level you should be seeing 29.5" Hg on the gauge very easily which equates to a 98.6% vacuum. The higher the vacuum the more air you are removing from the blank. The more air you remove, the more resin you get back in when you release the vac and the more thorough your stabilizing will be.
 
Thanks guys, for the clarification on pump specs. I have a little better understanding. I think that the pump I have is perhaps lacking what I need. I will put my vacuum Vessel together and give the pump a try. Thanks again for the helpful responses.
 
To be honest you aren't going to pull much more than about 27" in Denver anyway. That's all we get here in Reno with the 'best' pumps. It should still work anyway. I had one that would easily read 29 1/2" on the gauge at sea level and when I moved to Reno I've never gotten more than about 27 ish out of it. Reno is 4000' above sea level.
 
MesquiteMan said:
KenV said:
I have a gage on the vacuum chamber that reads inches hg. 28 is a good number.
Click to expand...

Ken, with the utmost respect, I have to disagree with you if you are at sea level! If you are at 1,500 feet above sea level, then yes, a 28" vacuum is great. However, at sea level, a 28" vacuum is only a 93.6% vacuum. Using a rotary vane oil filled pump, at sea level you should be seeing 29.5" Hg on the gauge very easily which equates to a 98.6% vacuum. The higher the vacuum the more air you are removing from the blank. The more air you remove, the more resin you get back in when you release the vac and the more thorough your stabilizing will be.
Click to expand...

28 is the good WORKING number at the GAGE at the chamber-- I do not know how much further than that my pump will go nor do I really care -- There are few that will reach that without extra margin of capacity, but it is possible I am getting all there is to get --
 
OK, here's a question for the vacuum experts. I have several diaphragm pumps I use for pulling sap during sugaring season. None of them give a vacuum rating. They're all rated for "X GPM at Y PSI." Can I derive a vacuum rating for these pumps?

Gary
 
The easy and inexpensive way to see if any vac pump sucks hard enough is to attach a vacuum gauge to it and see how much hg or mb it pulls.

Gast does make some awesome pumps that enjoy a solid reputation in the composites world but the 0211 isn't one of them. It's a fine pump but it wasn't made to pull more than 20"
 
Since the 0211 isn't enough to pull more than about 20 I have ordered a vacuum gauge on ebay. Should get it by the end of this coming week . I'll hook it directly onto the input and see what happens. If I have to buy another pump...oh well.
 
79spitfire said:
To be honest you aren't going to pull much more than about 27" in Denver anyway. That's all we get here in Reno with the 'best' pumps. It should still work anyway. I had one that would easily read 29 1/2" on the gauge at sea level and when I moved to Reno I've never gotten more than about 27 ish out of it. Reno is 4000' above sea level.
Click to expand...

You will never get 27" Hg in Denver if you are at 5,000' ASL. The maximum theoretical vacuum for 5,000' ASL on a standard atmospheric day is 24.98" Hg. I have a calculate on my site that you can input your elevation (and even your barometric pressure for the day if you choose) and it will compute your max vac. TurnTex Woodworks - Maximum Theoretical Vacuum Calculator
 
Vacuum tips

My trade for most of my adult life was Air Conditioning. The purpose of pulling a vacuum is not only to "remove air", but also to remove any moisture. Water boils under a vacuum. The "smoke" you are seeing is more then likely steam. It is very important to change the oil in a vacuum pump very regularly, as the oil absorbs some of that water also, and can give you that vapor/steam. Always use vacuum pump oil, as ordinary oil products for other purposes aren't designed for vacuum pumps. Also, I would recommend checking the seal on your pots to make sure they are not drying out, and sealing improperly. When it's not sealed it will be drawing air in, which, of course, is full of moisture (especially here in the South-east). If I remember there is a special silicone grease to keep seals pliable. Ordinary oil degrades rubber seals. Most quality Vacuum pumps I have used have a viewing window on the side to look at the oil. If it is the least bit cloudy it is starting to get moisture in it, and needs to be changed.
 
MesquiteMan said:
79spitfire said:
To be honest you aren't going to pull much more than about 27" in Denver anyway. That's all we get here in Reno with the 'best' pumps. It should still work anyway. I had one that would easily read 29 1/2" on the gauge at sea level and when I moved to Reno I've never gotten more than about 27 ish out of it. Reno is 4000' above sea level.
Click to expand...

You will never get 27" Hg in Denver if you are at 5,000' ASL. The maximum theoretical vacuum for 5,000' ASL on a standard atmospheric day is 24.98" Hg. I have a calculate on my site that you can input your elevation (and even your barometric pressure for the day if you choose) and it will compute your max vac. TurnTex Woodworks - Maximum Theoretical Vacuum Calculator
Click to expand...

Neat calculator!

It showed me two things,
1) My old vacuum pump had a bad gauge
2) My current pump is working just fine, I consistently read just over 25" (we're at 4200')
My current pump is a Robinare, that is only rated at 1.6 cfm, but because I have a small chamber has always seemed to do a good job. It always worked good on A/C systems so I didn't worry about it.
 
Rockytime said:
Since the 0211 isn't enough to pull more than about 20 I have ordered a vacuum gauge on ebay. Should get it by the end of this coming week . I'll hook it directly onto the input and see what happens. If I have to buy another pump...oh well.
Click to expand...

Jusr got my cheapie vacuum gauge to day. Hooked it up directly to the pump and it pulled 22.5 inches. I think I'll try it. Hoping it will be satisfactory. Have to make my vac chamber. Probably experiment w/a quart jar. If it works I'll perhaps get a commercial one. I'll keep posted.
 
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