[11echo]

I'm thinking about building a pressurized sandblaster out of an old hot water heater. I want a semi large one that I can put a full 100# bag of sand in (didn’t want open bags of sand laying around) I have found a small dia water heater and have it cut open ...things are looking good up to this point! BUT now I'm looking at the bottom elliptical head off the water heater and was think "IF" I had a funnel shaped head with a 1 to 1 slope for and end, the job of direction the sand to the discharge piping would be so much more efficient, than if I just used the elliptical head that came with the water heater!!? ...Then I started looking at pressurized sand blasters that you can buy. They are smaller 20#, 40#, & 60#, but they either have a hemispherical head or and elliptical head! ...SO my question is, am I worrying about something that doesn't make that much difference in the world of sand blasters? ...OR should I be trying to "improve" sand delivery system? Anybody with any experience have any thoughts on this?

[home brew]

I am not sure about the head design. But I would be concerned about using an old water heater. How much pressure are you planning on using. Chances are that that water heater has been rusting inside and any amount of pressurization will split it. You could use an old propane tank that needs the valve replaced instead.

[oldred]

You are not building a sandblaster you are building a bomb That tank must be rated to hold the pressure it will be exposed to the same as if it were a compressor tank and saying "well I will limit the pressure" will not work because you don't know what will eventually become of the thing or if you might make a mistake on the pressure, quite possibly a fatal one since a tank that size even at 90 PSI would most likely be fatal at working distances. To compound the problem of the fact the tank was not designed to hold that kind of pressure in the first place you would be welding on it and using questionable designs on the ends. Please don't even THINK about doing that!

[11echo]

My Max working pressure is 125 psi, the hot water heater is 16 ga steel with 12 ga steel elliptical head at one end and the burner end is 6 ga. Max rated pressure for the heater was 150 psi ...remember this was a small heater. I've cut maybe 14" off one end and flipped the burner end around and was going to weld that back, but got to thinking about the shape of the sand delivery end.
I have built two air receivers out of old water heater with no problems, I tested each one with more pressure then I would normally use ...at a distance for afew hours. If you look at some of the "store bought" ones the welding and assembly is questionable in my mind!
...SO NO thoughts on the shape of the end?

[CDJr]

Ive gotta ride with oldred on this one. I personally would consider that a ticking time-bomb and Ill tell ya why...theres much difference in the amount of stored energy in a tank with 125 PSI of water and 125 PSI of compressed air. When the tank fails, which WILL happen eventually, if its full of water it simply develops a leak...no harm done, other than a lil soaked carpet or flooded basement. However, if its full of compressed air, well, lets just say its gonna do alot more damage than ruining your carpet, I assure you. And I damn sure wouldnt wanna be standing there sandblasting when it happens. (This is also the reason you dont use PVC for compressed air lines). Look at it this way, how often do water heaters go out, on average? Each time youve had to replace the one in your home, imagine a bomb going off instead of a simple water leak, cuz thats basically what youve got goin there. I hope you reconsider

[Rob Keller]

I built mine out of a old commercial pool filter.

Its stainless & has this big ole' HONKIN brass{looking} dual port in the bottom.

I was looking for a pressurized unit @ the time but Granger's was almost $1,000.! & only holds 110Lbs.

Mine will hold 800Lbs. No problem A real PITA if you want to move it.

So this was not very involved for me, a pressure reducer with a gage on the inlet & I used my Snap~On Gravity feed sand blaster .

My unit needs a BIG compressor & has NO way to meter the sand flow but will blow the medium 10' before I hit the trigger with 10 ~ 15 PSI intake MAX!
And when you pull the trigger it really blows a lot of stuff.

{By the way don't load the sand under a tree that has acorns!!!}




R

[oldred]

Rob is that a suction blaster or is it pressurized? If it is suction then you have a great idea but if it is pressurized do you have any idea what the pressure rating is on that thing? Did you pressure test it? It may be ok but I sure would be concerned for exactly the reason CD mentioned. A similar air tank would require a burst test rating of at least 250 PSI with a working pressure of about 175 PSI and a water tank is usually nowhere near that so the safety margin is questionable at best.

Echo, On that water heater several things come to mind first it was never rated anywhere near high enough even when new (150 PSI for a water tank is not even in the same ballpark as 250 PSI for air which is what it should be rated), as CD said have you thought about how often water tanks leak? That minor water leak at 50 PSI or so could be deadly with air at 90 PSI, plus it is old and discarded, why? Do you realize that the way the ends are turned makes a huge difference in the strength? You mention the thickness of the steel but do you know WHAT KIND of steel? There is a HUGE difference in the strength of certain kinds of steel and water heaters are usually made of low tensile mild steel and will not take the expansion and contraction that WILL occur when you use this thing due to pressure changes, there is a hell of a lot more to the strength of that tank than just steel thickness! There have been numerous accidents related to using non-purpose tanks for compressed air with old water heaters at the top of the list, some of these accidents were very serious. If you had read some of the safety bulletins and looked at the pics of ruptured tanks that I have seen over the years you would not even get near one of those things never mind consider building one. I am not joking I have been doing this for over 35 years and I have seen tanks rupture and it CAN happen to you! A tank the size of that water heater with 90 PSI could easily take out the side of a building and kill or maim anyone nearby so do yourself a favor and reconsider doing this before it is too late.

[Rob Keller]

its pressurized but like i said I have it regulated in between 10 & 15 Lbs. MAX.
The sand will run out of the hole if the hose is not hooked up , just like a hour glass.

I tried just a air valve but it came flying out!

once it get the pressure on it it keeps flowing until it get back to zero.
If I remember correctly {been 10 years since I used it last} I was @ 5 PSI.
It gets its power from the air @ the Gun.

Ive spent hours eating sand out of that thing.




R

[oldred]

That'al work! I hope you are joking about eating (breathing) that sand? Are you using sand or one of the "purpose" blast media? Sand will kill you nearly as quick as an exploding tank! Well not really but it is extremely dangerous and if you do use it then be very careful and use the right respirator or better yet a supplied air set-up. Also be careful where the dust drifts to because you would not want to expose your family, neighbors or even your pets to that stuff, it really is that bad so treat it at least as bad as modern ISO containing paint overspray. Really you can breath enough silica in just a VERY short time when using sand to do serious damage and even a tiny amount will do some damage.

[ccb]

My friend is a sandblaster. His tanks that hold 100 # of sand are about 1/4 inch rolled steel.

[Rob Keller]

Yea Just a expression.

But it gets into everything .

Like going to the beach during a hurricane.

I used diving goggles a paint respirator with a full face clear shield & a motor cycle helmet ,welding gloves And a firemans rain coat & it still got in some.


Bugs Gave me a fresh air system in a big orange box that I need to get working some day it has provisions for 4 external ports.

I have to dig it out & do a search on getting the rest of the parts .

But I will have to get some land ...then a shop...then a spray booth...by then everything will have changed again & I will get that tilted dog's head look when I go for supplies .

If I will be able to even BUY paint by then, not on the black market.




R