Air Compressor Max PSI

[MK1_Oz]

Been trying to sand blast a few small items but after 20 or so minutes I start to get lots of water out of the nozzle that blocks up the sand. Having thought about it I believe it is because I am running the blast tool at the max PSI the compressor can put out (about 105psi from memory). I bought a new water trap but I have thought about it and for the trap to work there needs to be a pressure reduction through the regulator/water trap (lower pressure air holds less water?)

I cannot really sand blast at a lower pressure as it becomes ineffective so can the storage pressure of a compressor be upped in any way? I have not looked but assume the compressor will have a max pressure stated on the tank.

[Danny M]

how big is the compressor

[MK1_Oz]

15.54 cfm or 440 lpm. now that you made me go look at it I saw it says max operating pressure of 140psi. I dont think I have ever seen the gauge past about 110psi.

[Danny M]

Sounds like better water trap time

[MK1_Oz]

if the compressor is putting out 110psi and the regulator is set at 110psi then the water trap wont work anyway?????

[ozstang65]

Is the water trap filling up or is it just letting water through? You can get autodrain filters that automatically empty when they are full. Another thing to try, if it is possible, is to locate the water trap some distance away from the compressor. As the air cools more moisture will drop out of it.

In our batch plants we run an air manifold usually about 10+ metres away from the compressor with an autodrain on it. Seems to work quite well.

I don't think your problem has to do with psi, but with air temp.

[MK1_Oz]

the new water trap is an auto drain jobbie and it is not filling up. It has crossed my mind to move the trap closer to the work. I have also thought about putting in a T piece with a drop line to assist water in the airline to fall via gravity out of the main line.

Only issue is that this is a bit of work to setup for only a few hours blasting. Maybe the warmer weather will help.

[maxrs]

Why not remove the bung at the bottom of the compressor and drain the main tank.
I bet it's full of water, especially if your working in humid conditions.

Let all the air out before you undo the bolt. it will drain water under pressure with very little psi in the tank.

[jpayne]

Yes, as Maxrs states empty the tank...should be done at the end of every session, mine usually had enough in it to leave a significant wet patch pool under it every use.

cheers,

JP

[MK1_Oz]

Will do. I bought it second hand so really I should have changed the oil and drained it before I started using it.....but I am not a patient man!!!!

[Steven F]

Do you run any metal pipe at all between the compressor and the blaster? If the air coming out of the system hasn't had a chance to cool then the first place the water will condense is as it comes out of the hose nossel. Won't matter how many times you drain the tank or how many traps you have. That's why your problem gets worse as the compressor heats up after 20 minutes of running continuously as the only place the air can cool is in the tank.

If you run a decent length of copper pipe around the garage that'll give the air a chance to cool and the water within condense. If you don't have space, bend the pipe so it looks like the coil on the back of a refridgerator and fix it to the wall next to the compressor. Fit your water trap and reg at the end of the copper section and fit your T piece with drop section below the trap.

[MK1_Oz]

so does the water trap work by just letting the water that is already in the lines drip into it OR as I previously assumed, does it capture the water that condenses in the regulator due to the sudden drop in pressure?

[Steven F]

A little of both but when your taxing the compressor to the max, like using a sandblaster, it doesn't really have time to either very well if its right next to the compressor.

Have a read of this link. Shows how someone else reduced the water in their air system
http://www.mig-welding.co.uk/air-system.htm

[MK1_Oz]

Thanks Steven. Interesting reading.

Now that I have 2 regulator/water traps (the old one leaks air but still works I guess), could I install one reasonably close to the compressor that reduces the pressure and the second close to my work? I could even step the pressure down between the two to maybe assist with getting the water out.

Anyway, one of my initial questions of this therad was can I increase the storage pressure of my compressor?? It says it is rated at 140psi but the gauge never shows more than about 110psi. Are the pressure switches adjustable?

[ozstang65]

Stop thinking pressure drop, start thinking temperature drop.

[MK1_Oz]

gotcha

[chris pfeiffer]

Hi , your pressure is too high and you probably need to replace the media

Using high pressure takes the sharp corners of the garnet very quickly and it looses its effectiveness

Try new garnet and drop the pressure to 70 ish, it will work just as well as at 110 and give your compresser a fighting chance of keeping up and supplying dryer air

Chris

[MK1_Oz]

Will give it a try Chris