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Considering buying a pressure pot to use with my 3 1/2 HP compressor until I have the $$ to buy a new compressor.
Called Sanblast and asked if the Model 70-S would work with my compressor and they told me it wouldn't. He said the c.f.m. was too low. He didn't explain to me how to convert the s.c.f.m to c.f.m #'s, just stated that industrial blasters have c.f.m stated on them.
So, does anyone know how I figure out how many c.f.m. this will convert to? This is on my compressor:
8.5 scfm at 40 psi 6.8 scfm at 90 psi
Thanks!
-------------------- Amy Brown Life Skills 101 Private Address
Posts: 3502 | From: Lake Helen, FL, USA | Registered: Feb 2001
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Frankly, I don't know the difference between scfm and cfm. I think what you are looking for is a high number of cfm and delivered at high pressure. e.g. 10cfm@90 psi. High numbers on both sides means, in effect, that your compressor can keep up with the demand for air that you place upon it.
A compressor like that would most likely be a two-stage type. All that means is that the first stage compresses the air, delivers it to the second stage where it is compressed further, and then to a storage tank. A single stage type only compresses the air once, and this type in most cases can't keep up with a high volume at high demand requirement.
Hope this helps, and maybe somebody else can explain it better.
A couple of other things came to mind after my original post-- Concerning your electrical setup in your shop. Most compressors-single or multi-stage, have motors that are considered fairly high-draw items. They don't need much excuse to pop a circuit breaker or blow a fuse. You might give some thought to a separate cicuit for the compressor to run on. Also, the 2-stage types may allow for wiring for either 110 volt or 220 volt. If 220 is already available in your shop, that would probably be the way to go.
The last item concerns portability. Bigger compressors don't lend themselves to being moved around very much, unless they are on wheels. Even then, they tend to be top-heavy, and tip over easily.
I have two in my shop. The smaller one is light enough to be picked up and carried to a job site, but it is for airbrushing only. The other is a single stage unit more than adequate for my needs, but still not big enough to say spray a car.
[ October 09, 2001: Message edited by: Bill Preston ]
-------------------- Bill Preston Fly Creek, N.Y. USA Posts: 943 | From: Fly Creek, N.Y. USA | Registered: Jan 2000
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The cfm and scfm is a temperature related conversion. Scfm is measured at 60 degs F. Used for the purposes standardizing the measurement of gases to be sold commercially. The numbers you have are the delivery rates at those particular pressures. Your compressor will keep giving you those rates with the tank that you have on it now. If you change the size of your compressor pot or add an additional air receiver you will not change the delivery rate of the compressor. You will deliver them to a larger volume tank that will take longer to fill to capacity at the working pressures. When you release the pressure faster then it is made up by the compress, you are going to have some problems. Don't worry about the difference between scfm and cfm, listen to what Bill said. The higher the number gets on each side the more air you have to use. You probabaly won't be using a compressor to give you much more than 150 psi in most cases, more likely 120-130 psi is more common. Many have pressure limit switches that are set at 90 psi, yours may be set there or a little higher since you are give 90 psi as a reference. What about increasing the size of your compressor instead of the tank.
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Amy...I have done a lot of sandblasting over the years, although most of it has been using a sansblaster on vehicles and steel tanks.
I have done it successfully with a 3.5 hp single stage and a 5 hp dual stage and always had to take a rest and let the compressor catch up.
For a short period of time I was working in a shop that had two individual 5 hp dual stage compressors piped together. when blasting we would throw on the breaker for the secondary compressor and then do the blasting...No need to take a break with that setup...However...It usually ended up that we took breaks just because WE needed the break, not the compressors!
-------------------- Dave Grundy retired in Chelem,Yucatan,Mexico/Hensall,Ontario,Canada 1-519-262-3651 Canada 011-52-1-999-102-2923 Mexico cell 1-226-785-8957 Canada/Mexico home
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Amy, I bought a 6 horse single stage compressor with an 80 gallon storage tank at Sam's Club for about $400. I can run a small pressurized sandblast pot with a 1/8" nozzle with it... but you wouldn't want to do any big signs with that setup. It's fine for doing smaller signfoam blasting. I have a 1 horse compressor with a small tank that is very portable when I need to take a compressor with me for airbrushing. There was a 2 stage 6 horse compressor at Sam's club for $800 last time I looked. LE
-------------------- LazyEdna in RL known as Sara Straw from southern Utah 5 National Parks within 3 hours drive Red Rock Heaven Posts: 776 | From: Aurora, Utah, USA | Registered: Nov 1998
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Amy, last spring I bought a new shop compressor.. it's 3.5 horsepower dual stage compressor and delivers 10cfm @90 PSI. It has a 30 gallon tank but even when I use alot of air (spraying with an HVLP gun or using airsaws and sanders) it doesnt run very long at all. It's also very quiet, it's in the garage on the wall adjacent to the living space in my house and you cant even hear it at all. I paid $485 for it at a local tool shop, brand name Ciason's. It's built very solid, not a single plastic part on it.
-------------------- "If I share all my wisdom I won't have any left for myself."
Mike Pipes stickerpimp.com Lake Havasu, AZ mike@stickerpimp.com Posts: 8746 | From: Lake Havasu, AZ USA | Registered: Jun 2000
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amy my friend in sarasota did a lot of sandblasted signs....he would get the signs all made up and masked then on fri he would go rent a diesel air compressor...the kind they use for jackhammers and such....and spend all weekend blasting the signs...and return compressor mon....this way he was only charged for a 1 day use...of it...and he had his own pressure pot and nozzel. was never outa proper air pressure...hehehehehe
-------------------- joe pribish-A SIGN MINT 2811 longleaf Dr. pensacola, fl 32526 850-637-1519 BEWARE THE TRUTH.....YOU MAY NOT LIKE WHAT YOU FIND Posts: 11582 | From: pensacola, fl. usa | Registered: Nov 1998
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