Portable Paint Removal Water Blaster

[Rick V]

Is anyone aware of small water-blast system for paint removal?

About 15 years ago when I worked at Atomic Energy of Canada Ltd.; the company assembled a water blaster that fit inside a small tool box. It was very simple:
a) a 1/4 - 1/3 HP electric motor,
b) a high pressure (10,000 psi), low volume (quart/minute) water pump,
c) a 1 gallon jug of water,
d) a 5 foot-long high-pressure hose, with
e) a tiny metal nozzle that emitted a mist-like fan of water.

The unit was made to remove packing seals from around industrial valve stems.
However, I found it did just an amazing job of striping paint!
E.g. From a distance of about 3 inches, I moved the spray nozzle across a steel shelf having baked on enamel finish; behind the nozzle a 3 inch wide swath of bare shiny steel was left - all the paint was simply gone! All this in just a few seconds.

Note: The unit put out only about a quart of water per minute but a very high pressure of 10,000 psi, very different from today's conventional pressure washer operating at about 3 gallons per minute and 3,000 psi. The trick to success was the high pressure: while 3,000 psi can't remove baked-on paint too well, 10,000 psi sure can! There was no mess since so little water was used.

What a great tool! Man I could have used such a device many times!

However, I have never seen such a product to buy. I’ve searched the Internet for something like this but I can't find anything like it - just huge horsepower industrial trailer-size units that cost big $$$$.

My question is: Has anyone come across anything like this - a small high pressure, low volume, water blaster paint remover?

Rick V

[llamafur]

did it use a blasting medium like sand? there are attachments for pressure washers that do wet sand blasting

[Rick V]

did it use a blasting medium like sand? there are attachments for pressure washers that do wet sand blasting

Nope - just clean water. That was part of its appeal - so simple and no mess.
Rick V

[tigmusky]

sound like the HOT ticket

Daye

[Rick V]

After searching the Internet, it seemed that 10,000 psi may not be enough pressure to remove paint. The literature seems to suggest more like 15,000 psi. After 15,000 psi pumps seem to give way to something called an 'intensifier'. This appears to be hydraulic ram/piston that stokes the water in a cylinder up to very high pressures - like 60,000 psi. This pressure is sufficient to cut steel and is used to do just that in commercial 'water-jet cutting'.

Anyway, details on a 'small' 15 HP unit outputing 1/4 gallon per minute at 60,000 psi are available on the following web site:
http://www.industrialmotionsystems.c...tem-slv15.aspx

I've attached some information from that web site.

Still, this is not what I saw back at my old work place; that unit was much smaller consisting only of an electric motor (~1/2 HP size max) and a small pump - that all fit in a small tool box!

Any suggestions?

Rick V

[tigmusky]

can you talk to someone at your old work place . to get hte name of the company??

[Rick V]

Can you talk to someone at your old work place . to get the name of the company? - tigmusky

Sadly no. I tried that by email and by phone ~11 years ago, about a year after I had left the company, but he never returned the communications. By now he has retired, along with the others that were working in that project and area.

Still, there might be someone around; I'll see if I can pursue that. Good idea - thanks.
You are right, the name of that pump is looking real important!

Rick V

[Rick V]

Still, there might be someone around; I'll see if I can pursue that. Good idea - thanks.

A few phone calls to now all retired workers, I found the project leader and I got most the scoop!
My memory wasn't perfect

- the water pump was not mechanically driven by an electric motor (there was no motor); the pump was driven by compressed air - what is termed an 'pneumatic-driven liquid pump'.
- the nozzle body was stainless steel with a sapphire orifice of 0.015 inch diameter
- as well as removing paint, the fan nozzle cut concrete!
According to the project leader, you had to be careful not to damage the steel objects around the orifice!
This means it might be capable of removing mill scale from steel!

The pump was made by Haskel with about a 100:1 ratio.
e.g. 105 psi air input yielded 105 x 100 = 10,500 psi liquid output pressure
The output water volume was quite small, about 0.2 litres/minute [~7 oz/minute] (US)

All the Haskel pump details are available at the web site:
http://www.haskel.com/corp/details/0...TI9763,00.html
Download the pdf Brochure titled, "Haskel Liquid pumps". Thse pumps are quite small; weight about 6 lbs and you can hold it in your hand.



According to the Haskel pump charts, the likely pump was either a MS110 or MS188. These are the smallest pumps at just 0.33 horsepower output. However, the small pumps require a lot of air to drive them: 15 scfm @100-125 psi. That's the output of a typical 5 hp electric air compressor or 9 hp gasoline driven air compressor.
Note: the larger volume output pumps require much more air.
0.33 hp 15 scfm
0.75 hp 45 scfm
1.5 hp 70 scfm
So, it looks best to stick with the smallest pump 'M' to conserve air, besides it creates less mess due to small output of water – less contamination.

Pump Model Letter Coding
M .875” stroke .33 hp miniature pump series
S Stainless steel hydraulic piston and body
M = is good for petroleum-based oils, kerosene, water with 5% soluble oil.
MS = same as M + plain water, diesel fuel.
So it looks best to stick with the MS designation (M= 0.33 hp size, S=stainless for water usage)

How do these air/liquid pumps work?
The pumps automatically reciprocate on a differential piston principle. A large piston driven by relatively low (air) pressure drive acts directly upon a smaller hydraulic piston (liquid contact). The nominal ratio between piston sizes (area) is indicated in the model coding and approximates to the maximum working pressure.
e.g. MS 110 implies 110:1 ratio. 115 psi air input yields 115 x 110 = 12,650 liquid output pressure
Initially, the pump will cycle at maximum speed acting as a transfer pump to pressurize downstream. It will cycle at a slower rate as the fluid meets resistance until it stalls at maximum output pressure. At that point no input air is needed to maintain output pressure. When a pressure drop downstream occurs, it will recycle as necessary in an effort to maintain maximum pressure.

Main users of such pumps appear to be the oil/gas industry, the US Navy and auto-manufacturers.
Cost? Dealer price for the small 0.33HP pumps appear to be about $1300! However, such pumps are available surplus and a quick review of ebay turned up prices varying from $75 to $500 with the average being $150. Here's a typical ebay ad.



Note: That M-110 ebay pump is not suitable because it is only 'M' designation not 'MS' - you need the S for Stainless (handling water) after the 'M' (for 0.33 hp size). The ratio '110' may just be adequate or aim for the higher '188' ratio designation.


So for the scroungers among us, seeking out a surplus cheap MS110, MS188 or even MS220 is the way forward.

Rick V

[dougspair]

...Well the place I work now...we have an 'air-less' sprayer....34:1 ratio....100 PSI air, 3,400 psi paint.....will really mess-up your hands, fingers whatever....like 'amputation time' for any liquid injected into body at this pressure....orifice from .007-.018"...depending on what you're spraying...even with .011" at 2,500 PSI...will blast right through your hand....and gloves....
10K+ PSI.....cut your fingers off real quick-like....most of these things are not designed for 'hand work'.....and usually have safety guards around the nozzles...even at 2,000-3,000 PSI....
Figure it out...if it will blast off paint and mill scale......what might it do to your hands....?

[Rick V]

10K+ PSI.....cut your fingers off real quick-like....most of these things are not designed for 'hand work'.....and usually have safety guards around the nozzles...even at 2,000-3,000 PSI.... Dougspair

I fully agree with you. No Question that this is a potentially very dangerous tool to use!
- That may be why you don't see such tools available on the 'consumer' market

I do seem to recall that the operator in my former workplace dressed with special gloves (kevlar over chain mail gauntlets) and always wore saftey glasses covered by a full face-shield with kevlar neck protection.

On the other hand, if you do take proper safety precautions, the tool has many advantages compared to say sand-blasting as far less air is required, you have more control (removal can be varied by adjusting the air pressure or 'on-the-fly' by changing the nozzle to work piece distance) and there is far less mess and clean up.

Dougspair, good to hear from someone with relevant experience using such a water-blaster.

Rick V

[tigmusky]

very interesting. safety would be the biggest draw back. It would be fun to play with one .

Daye

[Darkacre]

Nice thread. I'm also trying to build a portable packing/paint remover. I've build a few air-hydraulic systems for hydro-static pumps up to 10,000 psi water. After some experience, high pressure water doesn't scare me, it is the high pressure air that scares me. But looking at this thread, concentrated high pressure water from a very small orifice can be very dangerous also. But I will take all precautions and try anyways...

So far I have a Haskel HF-300 pump [.5 liter/min output]. I'm in process of obtaining a .015" nozzle [with a guard]. So my thinking is to put a regulator on the input air [50 psi max X 300 ratio = 15,000 psi], and for safe precautions, a 50 psi safety valve on the input air. On the water output I will also put a safety valve ~ 15,000 psi. From the output (with the 15,000 psi relief valve), I will use a 20,000 psi working pressure hose ( about 1/8" diameter) then hook it up to a 6" long Stainless steel tube (1/8" diameter hole, 1" thickness), at the other end of 6" tube, hook up a nozzle that forces water to come out at 90 degree. Of course I would need to put a 10 micron or less filter somewhere along the way.

Does anyone think this is NOT a good idea? Any help will be appreciated .

[soutthpaw]

from reading the specs, make sure you control input pressure and volume of water

[Rick V]

Originally Posted by Darkacre

Nice thread....Any help will be appreciated .

I replied to you PM in detail.
Good Luck with this!

[S obsessed]

This is a cool item and would be sweet to make. In a little searching for this stuff I came across these guys that make a system already that is capable of up to 36k psi. http://jetedge.com/content.cfm?fusea...&product_ID=94 I am not sure on pricing as you have to request a quote. I might do that this up coming week.

[DSW]

Interesting Rick. We used Haskel's to transfer, AIr, O2, Helium and Argon in the dive industry from larger LP cylinders to dive cylinders at operating pressuers after the large cyl had dropped in pressure from filling by cascade. They also use them to charge small O2 cylinders for in flight use in airlines.

[jones6780]

When I worked for the Air Force there was an area that used 15,000psi to clean sealant and adhesives from F-15 wings prior to overhaul. It was http://www.aquamiser.com/
Even at 15,000 psi it would not remove zinc chromate primer. It would however cut you to the bone.
Russell

[Rick V]

Originally Posted by jones6780

... Even at 15,000 psi it would not remove zinc chromate primer. It would however cut you to the bone.
Russell

Ah but what would happen if you painted your body with zinc chromate primer?
Sorry... just couldn't resist.

[DSW]

Originally Posted by Rick V

Ah but what would happen if you painted your body with zinc chromate primer?
Sorry... just couldn't resist.

You'd probably make a very well painted corpse when you died from the zinc poisoning...

[bert the welder]

So for those of us in the cheap seats:
You hook up a high pressure air line, and a water line to this little Haskel thingy. The air drives a big piston that pushes a little piston that pressurizes the water, sending down a really high pressure hose to a sapphire with a teeny tiny hole in it, mounted to a stainless tip?
Am I warm???

[Darkacre]

Bert,

Well...the orifice size is critical, it must match your pumps output flow.
So far, I had a vendor tell me that only .006" orifice will work with my .13 gpm Haskel pump. And that a .015" will require higher gpm. I asked him what will happen if I put a .015", he said that you will not build up enough pressure to do the job...

[Rick V]

Originally Posted by bert the welder

So for those of us in the cheap seats:
You hook up a high pressure air line, and a water line to this little Haskel thingy. The air drives a big piston that pushes a little piston that pressurizes the water, sending down a really high pressure hose to a sapphire with a teeny tiny hole in it, mounted to a stainless tip?
Am I warm???

You got it Bert - Super Simple!

Originally Posted by Darkacre

Bert,
Well...the orifice size is critical, it must match your pumps output flow.
So far, I had a vendor tell me that only .006" orifice will work with my .13 gpm Haskel pump. And that a .015" will require higher gpm. I asked him what will happen if I put a .015", he said that you will not build up enough pressure to do the job...

Darkacre I only relayed what the builder told me; he said 0.015 inch. In your shoes, I would go with the vendor recommendation for a smaller 0.006 orifice. Too small an orifice just means less water out but still at high pressure - that will work but slowly. Too big an orifice and you will flows lots of water but at low pressure - that will not work.

In my PM, I said the unit output a fan spray - as if the orifice was a slot. I could easily have been wrong... memory of a one time event pushing 20 years ago may not be so good. If the orifice is that "teeny tiny hole", chances are it was just that - a round hole... and emitted a cone of spray.

[puddytat]

Isn't that the same principle that they use with needleless hypodermic injectors for people that can't stand being pricked by needles?.....a lot less pressure, but the principle's the same....just don't get any air in the injecting fluid.

If I remember rightly there is a system that is used to expand piping in a mould using high pressure water to expand the inside of the tubing.

The principle of intensifiers is relatively simple......area of the power piston divided by the area of the driven piston = the ratio required, and the surface area of the driven piston gives you the volume on discharge.

Enerpac make intensifiers that use air over hydraulic to produce the power for a press tool etc.
Ian.

[Darkacre]

Well, I got a quote for .006" orifice nozzles (1/4" NPT thread) for about $20. The problem is trying to find a gun without spending a fortune. It would be nice to have a gun for control. They are quoting $5K - $6K for a gun, not including the hose rated at 30K going for $1,000 (7 meters).

Other options:

-I'm thinking of using either 7500 psi Binks or Graco spray guns and limit my pressure to 7.5K to see if it works - these do come with .007" nozzles by themselves but they are for high pressure atomizer/sprayer, but I think the concept would be similar.....I can take a chance and try to take these guns to 10K as I'm sure they are proof pressure to 10K but probably not going to risk it..

-Mostly likely, the other option is to make a stainless tube with right diameter (I'm thinking 1/4" ID and 1" OD) with 1/4" thread at the bend-end to screw on the nozzle. This should easily handle 15K pressure if I don't make it too long (12" or less). The other end of SS tube is another 1/4" NPT female, I can just connect an Autoclave Engineering 30K psi needle valve (less than $50 on Ebay) for on/off and network it to the hose from the Haskel pump. This way I can have some control. This dimension also allows me to take the pressure to above 10K psi if needed.

-Or same as above without autoclave needle valve but instead control the airline pressure pumping the hydraulic pump. That is, if I turn the air pressure off (release), the pump would lose pressure very fast. But it maybe inconvenient to handle 2 hoses and a release valve.

As for hoses, well there are plenty of hydraulic hoses rated for 10,000 psi working pressure and 40,000 psi burst pressure that is compatible with water. You must buy ones with very good crimping at the hose ends.

I guess I will find out if it works or not when I get the nozzle in about 2 weeks. Doesn't hurt to try since I have most of the parts already.

[Rick V]

Darkacre, my recollection of the unit was that the only control was a valve on the air line. Makes sense as it is much easier to control 120 psi air that 10,000+ psi water. An air-line valve could be throttled to control the flow of air to the pump and thus the pump output.
The unit I recall was really pretty simple engineeing.
Red metal tool box housing the pump. Likely had an air line male fitting sticking out of the box for easy connection of an air line. Inside there may have been a shutoff valve (like a 90 deg swing lever ball valve) then the pump. Out of the pump I think there was a ss steel pipe exiting the box and sticking out a few inches. Onto this pipe end was attached the high pressure black hose. I don't recall how the hose attached to the steel pipe. The hose was about 4 to 6 feet long and connected to the ss wand - how I don't recall.
BUT, it was all simple and cheap stuff. e.g. If hose clamps could have been used... they likely were.
I hope that helps... I'll see if I can contact the fellow who who used this for more details.
Good Luck




The water wand appeared to be a three foot piece of ss tubing; it was about 1/4 ito 3/8 inch in outside diameter and rather light in weight. It curved somewhat, maybe over 30 degrees and had a short nozzle on the exit end. I presume that this nozzle was screwed onto the wand and housed the saphire orifice.