Criterion to choose a Positive Displacement Pump

What kind of tests do you want to perform? pressure? volume of tested components?

Fluid to use? Temperature combined with pressure?

Presure constant? Variable? Which dp/dt ?

Do you want to maintain pressure a longer time?

Try first to give some aswers to above questions and then it will be possible to give hints.

What kind of tests do you want to perform? pressure? volume of tested components?

Pressure testing for pipeline and vessels.

Fluid to use? Temperature combined with pressure?

Water at Ambient Temperature

Presure constant? Variable? Which dp/dt ?

mmm, I must increase the pressure in three steps, 33, 66 and 100%

Do you want to maintain pressure a longer time?

yeah, min: 1 hour, max: 4 hours

I regard a lot if you can helpme to decide

How high the pressure? How big the volumes of the vessels?

Water is a problem since the possible sources are not so many. It is possible to use also a pressure intensifier air-water or oil-water depending on flow and pressure requirements.

The optimal solution is a 2 stage pumping unit 1st stage can be any kind used only to fill up the vessel and 2nd stage is used only to compensate water compressibility (is low since water is stiff) and vessels dilatation under pressure.

Pressure up to 5000 psi, and vessels volume maximum up to 500 m³

2 Stages thats correct first (centrifugal) to fill the vessel, and second (piston positive displacement pump) to up pressure.

Centrifugal I know how to choose it, but Displacement I didnt :S

Better to use an oil-water intensifier. The pressures ration will be smaller. As a hydraulic pump you can use a low cost gear pump up to 3000 psi and use a ratio 2:1.

The advantage of the intensifier is that if 1st loop controlled a very fine pressure setting and a controlled dp/dt can be obtained.

In some industries, the pump used to raise the pressure to a test pressure is hand-operated.

http://uk.ask.com/web?q=hydraulic+test+pumps&search=&dm=all&qsrc=0&o=312&l=dir&siteid=

I saw your question a bit too late perhaps.But the answer is valid for even now.

For large capacity such as 500 or 5000 m^3,first choice is to use a centrifugal pump to fill up the vessel as fast as you can.( since you are testing water as the test medium - otherwise a different type of pump may have been needed)

Make sure that an air vent is available with a valve for closing at the topmost point on the vessel - otherwise you may have trapped air that will require hours of pumping to reach the pressures you need for testing.Complete evacuation of air is a must for

rapid hydrotest.

Once the vesel filled,isolate the centrifugal pump from the circuit and use a small capacity hydropneumatic pump for pressurising.With air operated pump you can select the max discharge pressure setting using the inlet air pressue,if you so desire using an air pressure regulator.

You only have to specify the max outlet pressure and inform the nominal air pressure available for driving the pump.These are plunger pumps with high ratios between the air piston and hydro piston areas.

For an example : if the air pressure available is 5 bar and the max pressure for hydro test is 200 bar,the ratio you need is 200:5 that is 40:1

If you have a 4" dia air piston and 1/2" dia hydo piston - it would be plunger in most cases, the ratio you will have is 16 / 1/4 = 64.That is with 5 bar air pressure you can obtain 5 * 64 = 320 bar!

Visit the site of Haskel pumps to learn more.

If you don't have compressed air, you may use an electrically operated plunger pump

with a relief and dump valve.Internet gives you several manufacturers to choose from.

If you still have difficulty, write back!

Thanks a lot, very usefull info!!!

I already have seen Haskel pumps, they are the best for this, I prefere it.

Electrically... mmm... I have search but I didn`t find some up to 5000 psi.

And, electrical... it hasn´t problems for this aplication?.. I dont know, like... low force when is raising pressure.

Have only just seen this so excuse me if I have missed something.

If you are pumping water or very low viscosity fluids at up to 5k psi an electric driven triplex plunger pump should do. They are built in a huge range of flows and pressures.

The basic (bare shaft) pump is available from CAT or Pratisoli (Italy) although CAT will provide a package.

BTW if you are based in the UK we could provide a package!

HydroScot