Joys of glass blasting

[LoserShoes]

I think the siphon feed takes quite a bit more CFM then the pressure feed.
I have a Harbor Freight blast cabinet and a Devilbiss 6 hp 2 stage compressor, and with a large nozzle that compressor is pretty much running flat out after a couple of minutes. It will keep up at 90psi, but barely.

Steve

[RiskyBusiness]

It makes some sense that the siphon type uses more air pressure. I think the air to media mix on the pressure pot type should be lower meaning that it takes less air volume for the same amount of aggregate. I am running a MUCH smaller compressor. I got the largest compressor that I could run off of 110. I didn't want to mess with wiring up 220 in my shop.

[prometheus578]

I think you're right about the higher pressure use. I have a 30 gal compressor with a hose connecting it to the tank of a 60 gal compressor (motor fried), which gives me a large reserve. Sure, takes a little longer to fill both tanks, but with the extra reserve, compressor gets a longer rest between cycles. (At least that was my theory)

[RiskyBusiness]

Just to clarify what I typed above, I really spoke without precision. The issue is the volume of air needed for siphon vs. pressure pot. I hate when compressor makers label their machines with useless big letters that read “150 PSI.” I have a bicycle hand pump designed for high-pressure road tires that will pump a pressure of 150 PSI. What matters for blasting is the volume; typically measured in CFM.

The siphon type uses a higher volume of air for a given amount of media.

[prometheus578]

Agreed.