High Pressure Water Blast

[Mtronics]

Hi All,

We have developed a system for a customer which blasts product at up to 5500PSi. Well atleast that is what the pump can deliver, what we have been asked now is a way of testing the water pressure exerted on the actual part being blasted. Our take on it is that once the water leave the nozzles it becomes a force on the part. What was required in the URS was a pump capable of 5500psi. SO with that, can anyone suggest a test which would determine the 'pressure' exerted on the part? It's not something we would be too familiar with..

 

[racookpe1978]

Here is a comparable question.

http://www.eng-tips.com/viewthread.cfm?qid=350383

You are asking about significantly higher water pressures and a much more valuable component. Hydraulic suppply companies offer many high pressure low displacement pumps - but you need to verify that the pump you are getting from any given supplier is going to work with water and not hydraulic oil. (Cooling rates, lubrication issues internally, corrosion issues, compatibly with filters and gaskets, etc. )

Rent a very high pressure washer from a tool rental company and measure the force (impact loads) at various distances before you spray your customer's expensive parts and pieces.

Knowledge does not always come from a book or Code or guesses or your "take on it"

 

[IRstuff]

Seems pretty straightforward to me. You would have a "standard" area test piece, say 1-inch square, with calibrated loadcell at a set distance from the sprayer, and measure the steady-state pressure imposed by the spray on the test piece. Since you stated that the pump only supplies 5500 psi, you will likely fail the test.

You stated, "We have developed a system for a customer which blasts product at up to 5500PSi," which implies that the surface pressure on the "product" needs to be 5500 psi, not that your line pressure be 5500 psi. You can trivially spoil the output pressure with too large a nozzle, so I can understand why the customer might think that you are trying to pull a fast one on him. You need to review your specification more closely. What does it say, exactly?

TTFN
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[1gibson]

I disagree. "Up to 5500 psi" means only that you will not exceed 5500 psi.

Put some magnets on your fuel line and you will get "up to 15% mpg increase*."

* = between 0% and 15%

Maybe this should be posted in the language forum first to determine whether or not you have met the spec, then worry about testing and possibly modifying the equipment.

 

[Mtronics]

Ok just to clarify, the testing isn't to see if we have pulled a fast one or whether we have met the spec. We have built the machine as per requirement from our client. They have since come to us to request a method of testing the pressure exerted on the part being blasted. But I appreciate that there are several factors affecting the pressure on the part. They plan on doing theoretical calculations, but want a practical test to back up their estimates. I am just not aware of any device readily available to give such feedback from a blast.

 

[IRstuff]

Oh, OK, so you could go with this, which has a max pressure range of 15-kpsi, or even higher:

http://www.tekscan.com/5076-pressure-sensor

http://www.tekscan.com/products/industrial/pressure-distribution-measurement-system

since the resolution is better than 0.1 in, you can even see what the pressure distribution looks like.

TTFN
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[ccfowler]

The nominal pressure capabilities of the pump and piping arrangement are only a portion of the issue. The specifics of the nozzle and spray pattern will likely play an important, if not controlling, factor in your system's performance.

Valuable advice from a professor many years ago: First, design for graceful failure. Everything we build will eventually fail, so we must strive to avoid injuries or secondary damage when that failure occurs. Only then can practicality and economics be properly considered.

 

[BigInch]

Ain't so difficult.
see att.

1gibson. "Up to" 5500 psi means a maximum of 5499 psi 5500 would be "equal to".

Independent events are seldomly independent.

 

[1gibson]

BigInch, I disagree, "up to" is inclusive.

Here is a 1 question pop quiz, multiple choice, you can get from 0 up to 100 points.

What is the highest possible grade on this quiz?

A) 99
B) 100
C) 5500
D) 0

But, wrong forum for that.

 

[IRstuff]

There's a difference between literal specifications and customer expectations. Clearly, for a contractual development, "up to 5500 psi" could be satisfied with 1000 psi, which would be nowhere near the customer's expectation.

My point was not addressing the literal specification, but the intent, which is that measuring an exit pressure of 5500 psi does not in any way assure that there's anything close to 5500 psi at the surface of the object being sprayed.

TTFN
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[BigInch]

The answer depends of if you use a mathematical or legal dictionary. Many legal decisions have been made on < 100. If 100 was specified, up to can be inclusive of 99. If 100.0 was the specified value, then up to can be inclusive of 99.9 The number of decimals specified in the contract matters.

Independent events are seldomly independent.