Sand blasting problem

[mhorowit]

Bob sold me his pressure pot and I picked up 50# of Al Oxide abrasive. No instructions with the pot.

I'm finding that the abrasive is clogging up the exit port at the bottom of the pot, and I have to stop and shake the pot every 5 seconds. Is this a moisture problem and how is it solved?

I've got the abrasive in the oven heating at about 150 degrees, thinking if there is moisture in the abrasive, that will drive it out. - Mike

[Robert Lees]

Re: Sand blasting problem

Yes, Mike, it's a moisture problem. Compressed air generates moisture. Get a dehumidifier in the circuit. Don't forget oil issues.

Not a Taylorcraft issue really...have you tried posting on groups.sandblasting ?

Rob

[mhorowit]

Re: Sand blasting problem

groups.sandblasting ?Rob

Rob - that's not a newsgroup. At least not one whose feed my ISP captures.
Is it possibly a sub-set of something like Yahoo? In the meanwhile I'll go look - Mike

[Gary Snell]

Re: Sand blasting problem

Mike

I would also check the exit valve for the blast media to make sure it's not open to much. Clogging can persist if the air to media ratio isn't set right. You might try throttling the media back a little bit. Works with my unit.

Gary

[mulwyk]

Re: Sand blasting problem

Mike:

I start the air going first and then open the media valve slowly until I get just the right flow that blasts but doesn't clog.

I was using this horrid black sand stuff for awhile that seemed to like to clog the nozzle, so I ended up removing the nozzle ceramic tip and blasting without it ...worked fine then!

Bob

[mhorowit]

Re: Sand blasting problem

Gary/Bob - that's just the info I needed. Thank you both.
This pressure pot didn't come with instructions, so I"ve pressurized it, then opened the sand valve wide open. I'll try your suggestions next weekend. - Mike

[Len Petterson]

Re: Sand blasting problem

Hallo fellows. Compressed air work like this!
As you increase pressure, the air heats up. As it cools it gives of the moister what originaly is in the air.
Therefore we install a airchiller/moister separator in large systems.
In a small system this becomes expensive so we install a dirt/water filter at the point of useage.
Run a pipe( 3/8" or 1/2" pipe, not hose)from the compressor as long as you can up the wall and down agin. Slop it torward the user end!
On the down pipe you put a TEE and you take the air from the branch.
Let the down pipe be a larger diameter pipe (1")then the feed line and Ca 2 feet long a redusing copling and a small 1/4" drain valve on the end of it.
Drain it dayliy!
Install a " large " dirt filter/airwater separator, If you run a 3/8" line install a 3/4" separator, as it is more effective.
If you have humitety levels over 80% and you want to paint with the system, install a coascolating filter. They are expensive but removers 95% of the water. Intall it after the filter/water separator, so it does not have to do all the filtering. Look in used industrial equipment places.

Len Petterson

[jdoran]

Re: Sand blasting problem

Mike,

Most pots are pressurized. The logic is that the air pressure in the pot, and the air pressure in the "sand" hose should be equal, or the sand can't (won't) flow out of the bottom of the pot and mix with the air zooming by thru the hose.

The nozzle size on the end of the hose is what regulates the pressure of the hose circuit. Too much pressure in the hose, and the sand won't flow out of the bottom of the pot. This is why the thing worked better with the nozzle removed.

Call a supply house that sells nozzles, or call the pot mfg to order the correct size nozzle for the sand you are using. The bigger the grit size of sand, the bigger the nozzle needed. Moisture can be a factor, but if you dump fresh sand from a bag into the pot, it is unlikely it is causing the problem.


John

[crispy critter]

Re: Sand blasting problem

Mike,
If you put a water seperator at the air intake point of your blaster will also help a lot....it won't completely cure it,but does help.It is also very hard to make it work at all in high humidity.Someone above said remove the ceramic nozzle....this does let it work much better but also lets it eat a LOOOOT more sand.

[hangarb7]

Re: Sand blasting problem

Mike,

When I was having problems, I finally figured out that I had to increase the pressure about 10 pounds to accomodate the fact that my compressor was inside the hangar and the blaster was outside. I had to make up for the long hose losses. The difference was night and day.

Jack

[mhorowit]

Re: Sand blasting problem

Great info folks; much appreciated. Never crossed my mind the pressure pot pressure would have to be greater than the feed pressure
For the record, I"m using Aluminum Oxide as the abrasive.

Apparently sand is not as efficient and if you don't use a respirator can cause lung problems, but some of you folks seem to be swearing by (Mason's) sand.
Sure would save on clean-up; couldn't hurt trying it out on a piece of scrap. - Mike

[Robert Lees]

Re: Sand blasting problem

and if you don't use a respirator

You will use one, Mike...the very fine dust gets everywhere.

Goggles too.

[mhorowit]

Re: Sand blasting problem

[QUOTE=Robert Lees]You will use one, Mike...the very fine dust gets everywhere.

Goggles too.

Rob - when you put on the respirator did you spend some time walking around saying "Luke, I am your father"

[Robert Lees]

Re: Sand blasting problem

No..I walked around cussing the air blue. It was August, and hot & humid, and salt sweat and powdered sand/glass irritates the skin like blazes!

Note to self: get this done by someone else next time!

[high time cub]

Re: Sand blasting problem

Mr Lees, Still at the coal face?