Sand Blasting Help

[Joe M.]

I purchased not one, but two portable, tank type sand blasters over the weekend; used black sand (silica carbide I believe). I was hoping one of the two would work long enough to blast 5 rims, but that was not the case.

The sand plugged up in the on/off valve beneath the tank in both units. If I beat on the valve with a hammer or shook the tank, sand would flow, but stop as soon as I stopped agitating the tank.

I removed the air filter that came with the unit and purchased a $30 filter from Tractor Supply. I used an air compressor rated at 6.4 cfpm @ 90 PSI. When the blaster was working, the volume of air was sufficient. I have several questions:

1) Can these units be made to work or am I wasting my time with cheap chinese blasters?

2) If I remove the on/off valve beneath the tank and replaced with straight pipe, would that just cause a plugging at the deadman tip?

3) Would a better air filter help? Coalescing type?

4) Do I need to use a bigger air compressor to push the sand?

Your input would be greatly appreciated.

[Gene M.]

Re: Sand Blasting Help

Buy a TIP made in USA. I would not even comment on the cheap foreign crap.......

Sand or media has to be dry dry dry...

[Larry M.]

Re: Sand Blasting Help

Agree with Gene about TIP blasters. Eastwood also has a couple of nice units....some more $$$$ than others. BRUT is another USA company that comes to mind.

6-7 SCFM is low for a good sandblaster. This tells me the sandblaster may have very small nozzles. Also your compressor is probably running all the time and the air is wet, as there is no time for the air to cool and condense moisture inside the tank. Most folks I know with good quality sandblasters have 5 hp compressors with 60-80 gallon tanks. I have a 3 hp with a 30 gallon tank and it is really too small....but I don't blast very often anymore.

Also be certain to wear a good cartridge respirator and use a blasting hood. A lot of sand companies went under some years ago because of silicone health lawsuits. That is why sales of many sandblasters went down and the enclosed BLASTING CABINETS with a exhaust vacuum/filter became extremely popular.

It may be cheaper to just hire this one job out....shouldn't cost to much. But if you plan to do many jobs, then consider my advice.

Larry

EDIT: For comparison, a 3 hp compressor puts out around 10 SCFM at 90-100 psig. A 5 hp compressor is more like 15 SCFM, with even higher pressures if 2-stage.

[Jim D.]

Re: Sand Blasting Help

I think your problem is that your compressor is too small. I have an Eastwood 100 lb. pressure blaster (re-branded Chinese) and my compressor supplies 15 CFM at 125 PSI. I sanded blasted a complete frame and all associated parts last week (took several hours) and it never plugged up once.

[Joe M.]

Re: Sand Blasting Help

The compressor was running continuously and the air filter had moisture in it. It has a 5.5 HP motor, but as soon as I opened up the deadman, the pressure started dropping immediately. Hard to believe there was so much moisture inside the compressor when the outside humidity was 18%.

I probably need to test it on a bigger air compressor before I give up on it.

If I removed the sand on/off valve under the tank and replaced it with a straight piece of piece would that help or just make the blockage occur inside the deadman.

[Paul J.]

Re: Sand Blasting Help

The compressor was running continuously and the air filter had moisture in it. It has a 5.5 HP motor, but as soon as I opened up the deadman, the pressure started dropping immediately. Hard to believe there was so much moisture inside the compressor when the outside humidity was 18%.

The compressor heats the air and the moisture condenses out in the lines after it reaches dew point. I've heard of one person who ran his air line through ice in a bucket, and then caught the condensate down stream. I don't know if this will work, but you obviously need better filtration.

I probably need to test it on a bigger air compressor before I give up on it.

Yes, your compressor is too small for this, but don't give up. Try turning everyting on, including the nozzle and then slowly turning on the air valve coming into the blaster and see if this helps.

If I removed the sand on/off valve under the tank and replaced it with a straight piece of piece would that help or just make the blockage occur inside the deadman.

With what I just said, this is the same as leaving the valve open.

Don't give up, and don't spend any more money (unless you just want to help the economy). Search for this on the web and try mckennasgarage.com under the Jag restoration. I think he was the one with the same problem as you.

Paul

[Joseph T.]

Re: Sand Blasting Help

I purchased not one, but two portable, tank type sand blasters over the weekend; used black sand (silica carbide I believe). I was hoping one of the two would work long enough to blast 5 rims, but that was not the case.

The sand plugged up in the on/off valve beneath the tank in both units. If I beat on the valve with a hammer or shook the tank, sand would flow, but stop as soon as I stopped agitating the tank.

I removed the air filter that came with the unit and purchased a $30 filter from Tractor Supply. I used an air compressor rated at 6.4 cfpm @ 90 PSI. When the blaster was working, the volume of air was sufficient. I have several questions:

1) Can these units be made to work or am I wasting my time with cheap chinese blasters?

2) If I remove the on/off valve beneath the tank and replaced with straight pipe, would that just cause a plugging at the deadman tip?

3) Would a better air filter help? Coalescing type?

4) Do I need to use a bigger air compressor to push the sand?

Your input would be greatly appreciated.

Do you have an oil and water extractor mounted between the compressor and the gun? This will help trap moister before it gets to the sand.

Joe

[Bill H.]

Re: Sand Blasting Help

The compressor was running continuously and the air filter had moisture in it. It has a 5.5 HP motor, but as soon as I opened up the deadman, the pressure started dropping immediately. Hard to believe there was so much moisture inside the compressor when the outside humidity was 18%.

I probably need to test it on a bigger air compressor before I give up on it.

If I removed the sand on/off valve under the tank and replaced it with a straight piece of piece would that help or just make the blockage occur inside the deadman.

I get moisture in my compressor even here at 7 - 12% humidity. I can get a 1/4 cup of water out of the tank in an hour and a half.

Do you drain the water out of the tank before blasting?

And any hose that's coiled up for storage will have moisture at the bottom of each coil.


Sizewise, the CFM dose sound a bit low for a pressure blaster. I'm running 10.2 on a glassbead cabinet (which has a smaller nozzle) and the compressor runs constantly (@ 100psi).

[Stephen L.]

Re: Sand Blasting Help

I have a tank style sandblaster connected to an 80 gal 5hp compressor. The compressor cycles on/off as it should indicating the compressor is adequate. After some use my blaster will plug due to moisture. I could use a better water separator.

To unplug the blaster all you need to do is shut the valve that is located between the main valve and the orifice valve at the bottom of the tank. This forces all the pressure into the tank and reduces the pressure in the nozzle resulting in the blockage to dislodge. After doing this turn that valve back on and you should be good to go until it plugs again.

[Joe M.]

Re: Sand Blasting Help

I removed the air filter that came with the larger unit and purchased a $29 air filter, but not a filter that traps oil and water. I think that is called a coalescing filter?

If I purchased a compressor, how large would I need for successful sand blasting? My neighbor's a/c stated 6.4 cfpm at 90 psi, but it could not sustain 90 psi. What do I look for to be certain that the a/c will sustain a high scfpm level? Is tank size and hp equally important?

I need to connect my blaster to a larger a/c and see if the a/c is the limiting factor. Of design is the limiting factor.

I know that the type of air filter is important, but I don't know little about how much to spend on an air filtration system. Time to google!

[Jim D.]

Re: Sand Blasting Help

If I removed the sand on/off valve under the tank and replaced it with a straight piece of piece would that help or just make the blockage occur inside the deadman.

I think you need to re-read your instructions in order to understand how your blaster works. The air flow is supposed to be WIDE OPEN AT ALL TIMES. The only adjustment you are to make is to the media valve under the tank. In order to eliminate clogging, the deadman should be open with air flowing and then you open the media valve the required amount for media to flow (this is usually less than 1/4 of the way open). Do your blasting and while the deadman is still open, close the media valve and let the media empty out of the hoses. DO NOT close the deadman at any time with media flowing or clogging will result.
Like I posted above, I just blasted for over 4 hours without a single clogging episode.

[George W.]

Re: Sand Blasting Help

I tried the sand blasting, but found the following method worked best for my wheels. I purchased from a building supplier,(Lowes) 2 gallons of brick cleaning acid. Not sure how to spell muratic. Put it in a large rubber garbage can, added enough water to cover the wheel and left for 24 hrs. One of the wheels needed an extra day in the solution, but all came out with paint and rust removed. I used a high pressure washer to remove the solution from the wheel.

I will be painting the wheels in the next couple of weeks and will post if there are any issues.

[Joe M.]

Re: Sand Blasting Help

I purchased a better air filter, read and followed the directions each time and it still plugged off. I will try again at some point in time; with a larger a/c as a test.

[Jeff P.]

Re: Sand Blasting Help

Hey joe i think a wise idea would be go rent a compresser from a rent a center. The material flow valve on the bottom of the blaster tank releases material and mixes that with air. so u want to balance the flow, i always used a ball valve on my blaster. WET AIR WILL PLUG THE SANDBLASTER. i always leave the petcock that drains the tank of the air compresser loose to just hear slight air escapement. Make sure u dont get a coarse grit sand and pitt those rims. My 7.5 H.P. two stage compresser w/80 gal. tank is one noisey machine but its all what U WANT that counts.

[Norris W.]

Re: Sand Blasting Help

Since there are several different configurations of sand blasters, when you say "on off valve below the unit" are you referring to the supply side, straight from the air compressor or a valve that shuts down the output. If it's on the air supply side it's hard to figure how it's getting plugged with media. I'm also assuming you're using a pressure pot and not a siphon feed. If it's siphon they're basically hobby toys and not satisfactory for doing anything requiring extended time blasting. If you've ever drained a compressor tank through a small opening you may have noticed that ice began to form on the opening. Depending on sizes, etc is it possible you're getting some freezing? (outside temp is irrelevant, I've seen ice on the drain fitting on a 100 degree day)

As far as the moisture/humidity issue, the moisture in your compressor has little to do with the humidity, but rather condensation resulting from differences in temperature. It's the same principle as a cold liquid in a glass that is at room temp............... it's gonna' condense moisture on the outside of the glass. In the compressor tank the condensation is internal. You're injecting hot air in a colder tank. I suspect that if you get rid of the moisture before it gets to the blaster your problem will go away.

It's also important to compare apples with apples in rating air compressors. The units that places like Sears call 5 horspepower that are on small tanks with wheels may have only a third the CFM output of REAL 5 horse compressors like the commercial types. CFM is all that really matters. High horsepower ratings on small home units are nothing more than marketing gimmicks.