# Sand blasting PSI setting



## Airluke (Sep 25, 2021)

I’ve been searching this site for information on setting PSI for blasting a car but can’t find much. I know how much pressure my blaster needs, about 70 to 90 psi continuously, and I can regulate the pressure between the tank and the deadman to whatever I want. Here’s my question; what size piloted unloader valve should I order for my compressor, Conrader has two ranges, 95 to 125, and 145 to 175 psi. I’ve got a 13 HP Honda motor on a IR 253 pump which puts out 20 CFM with a low speed pulley (550 rpm). The two ranges can adjust up or down by 30 to 40 psi according to the manufacturer Conrader. So either range will work but which would offer the most efficiency? I haven’t used a real blaster yet, just the little manually operated ones. But I have a commercial one now that pressurizes automatically (Clemco 300 lb). It seems to me if the compressor is able to supply the required air, then the lower range would be sufficient, and the higher pressure would be overkill. But if it can’t keep up with the nozzle output then it might help to start the blasting with higher pressure. Any experienced opinion much appreciated.


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## stevon (Mar 5, 2019)

Airluke,

I found this chart published for a Clemco SG-300. the size of the nozzle and type of blasting media and "your mileage may vary". Basically you have what you need to test and fine tune the blasting for your project. Please let us know your results.










Stephen




Airluke said:


> I’ve been searching this site for information on setting PSI for blasting a car but can’t find much. I know how much pressure my blaster needs, about 70 to 90 psi continuously, and I can regulate the pressure between the tank and the deadman to whatever I want. Here’s my question; what size piloted unloader valve should I order for my compressor, Conrader has two ranges, 95 to 125, and 145 to 175 psi. I’ve got a 13 HP Honda motor on a IR 253 pump which puts out 20 CFM with a low speed pulley (550 rpm). The two ranges can adjust up or down by 30 to 40 psi according to the manufacturer Conrader. So either range will work but which would offer the most efficiency? I haven’t used a real blaster yet, just the little manually operated ones. But I have a commercial one now that pressurizes automatically (Clemco 300 lb). It seems to me if the compressor is able to supply the required air, then the lower range would be sufficient, and the higher pressure would be overkill. But if it can’t keep up with the nozzle output then it might help to start the blasting with higher pressure. Any experienced opinion much appreciated.


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## iowagold (Jan 22, 2020)

we use an atlas copco 125 cfm for blasting.
BIG unit on a trailer.

media or soda blasting works better for cars.
just an heads up,

the other sand stuff eats up way too much good metal.

also look in to laser blasters.
they are the new way of dealing with rust, paint etc.
*click here for the laser rust removal search on you tube*


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## Airluke (Sep 25, 2021)

Thank you. Yes, I call it sandblasting sometimes but I’ve been media blasting. I use glass beads. Haven’t tried soda because I heard it doesn’t work for rust, but maybe it does with your pressure? Laser sounds great interesting, I’ll sure check that out, thanks. Probably too expensive up front for me but media isn’t real cheap either. 

Stephen thanks for that chart. I don’t understand it though. It seems to be saying that two sizes of nozzles, say 3/16 and 3/8 both use the same cfm (28) when supplied with 40 psi, for example. Am I missing something?

Im a little behind schedule but an ready to try out my bigger (IR 253) compressor when I measure the rings I put in which are way too tight in the cylinders. I didn’t check the ring gap. The wall to piston is fine in both cylinders, in fact the cylinders are just like new. ( could BE new, as someone rebuilt it just before a rod seized on it). The rings I got are from an aftermarket company and may be too big. Too big on outside or perhaps too small on I.D. Their crank, rods and bearings all fit perfectly. Anyway I’ll let you know how the blasting goes. I got the bigger (145-175) pilot valve which I’ll adjust down as far as it goes (105-145 about). Then between the tank and the blasting pot I’ll regulate down to 80 or whatever works best


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## iowagold (Jan 22, 2020)

you might look in to the power washer adapter for sand blasting.
kinda a cool concept and low dust that way.

the laser setups are cool.


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## Airluke (Sep 25, 2021)

iowagold said:


> you might look in to the power washer adapter for sand blasting.
> kinda a cool concept and low dust that way.
> 
> the laser setups are cool.


Thanks, I’ll look into those options. I’ve seen video of wet blasting but it looks to me like it ought to be done on a concrete floor that can collect the water and crud so the crud can be filtered out or evaporated dry. That’s down the road. 
As for my psi question, I just put a regulator on the tank outlet and leave the unloader valve at the high factory setting, 145- 175. I’m just waiting for new belts now so I can try the 253 out on the blaster.


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