So I must be stupid - air compressor


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Old 08-31-08, 01:06 AM
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So I must be stupid - air compressor

I bought a used .7 cfu compressor that is rated at 100 psi and supposedly is 3 gallon.
I was going to do some light sandblasting on glass. However, I go to use it and it will work for a few minutes and then the pressure just zeros out on me. I keep checking the regulator to make sure it is on high. The machine gets really hot, doesn't hold pressure and I am constantly adjusting the regulator to see if it will fix the pressure sometimes the machine runs and nothing happens.
So did I buy a dud? Is there anyway to fix it. I tried shortening the hose to see if I could get a little more pressure but no way. I can't even get a tiny air brush blaster to work with it.
It may be leaking but I am not sure how to fix the leak, plumbers tape maybe?
Or maybe its clogged. There is no brand name on it so I am sure it is a harbor freight type compressor, double tank.
Ideas? Help is appreciated.
 
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Old 08-31-08, 05:20 AM
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Welcome to the forums!

It doesn't matter what brand it is - it is too small for sand blasting. Sand blasting like painting requires a lot of cfm which you will only find in a bigger unit. A small air compressor like that is best for airing up tires and maybe nail guns.

The best you can do with that unit is to blast for a short time, then quit/rest until the compressor has recovered before pulling the trigger again.
 
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Old 08-31-08, 08:14 AM
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As Marksr said, the key word is "volume". And you don't have it on the 3 gallon tank. For sandblasting and painting, where you have the end of the hose basically "deadended", your volume drops almost immediately. I use double hotdogs for my nail guns, but a 26 gallon for painting and sandblasting in the shop.
 
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Old 08-31-08, 03:16 PM
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.7 cfm

here is a spec from one sandblaster (a small one)

Can be operated at 7 CFM with 3/32" nozzle; 25-30 CFM recommended for optimal performance
a quick cruise around the internet tells me that 7 cfm is about the minimum for sandblasters with many needing twice that, or more.

Does you blaster have any info with it? It should tell you the reqirements for air pressure and volume supply.
 
 

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