How to select the best hydrostatic pressure test pump

September 22, 2019

A lightweight two speed PSP hydrostatic pressure test pump on its portable reservoir


How do you select the best hydrostatic pressure test pump for your job and budget? Read our advice.

 

In this article, we explain how to select the best hydrostatic test pump to meet your technical needs and budget.

You have the choice between cheap low pressure brass trough pumps from distributors like Screwfix right through to 316 stainless hydrostatic pressure test pumps from big names in instrumentation. They will all do a job. Where do you start in selecting the best hydrostatic pressure test pump to meet your needs and suit your budget? 

 

What is the difference between a pressure test pump, a hydrostatic pressure test pump and a hydrotest pump?

In our world of Micropac pumps, they are all the same thing.

See also our own Hydrotest pump product page.

 

What fluid and test pressure are you running?

This question is vital. Fluids could be mineral oil, fuels, tap water, brine, synthetic hydraulic fluids or a massive range of chemicals. Pressures could range from a fraction of a bar up to 1000 bar plus. If you are running on mineral oil, life is easy.

Low cost “industrial” hand hydraulic pumps will probably fit the bill. Ball check valves working on oil will probably be good enough to hold pressure, but don’t be surprised if they leak over an extended period. You may yet need dedicated hydrostatic pressure test pump.

For fuels, you are running on lower viscosity and possibly the need for different seals, so we would suggest looking at a more specialist pump with low leakage poppet check valves. We wouldn’t use metal seated ball valves for low viscosity fluids. The same would be true of synthetic hydraulic and control fluids.

Low viscosities or special seals might push you towards sourcing a dedicated pressure test pump from a specialist. Low cost trough pumps will invariably be used on tap water, which in itself can be a challenge. Water is a very low viscosity corrosive fluid, so sourcing a pump that will hold pressure and not corrode out quite quickly can be the challenge.

 

How much should you spend on a pressure test pump? 

 

A lightweight two speed PSP hydrostatic pressure test pump on its portable reservoir

A lightweight two speed PSP hydrostatic pressure test pump on its portable reservoir 

You could spend 30GBP or 30KGBP. We would say buy something that will do the job on day one then continues to work as long as you want to use it. Whatever your budget, you need the unit to work properly on day one. Generally, pressure pumps are challenged by being left full of water for long periods before being used again.

There is inconvenience which can be costly in finding equipment doesn’t work when you really need it. Corrosion comes into play. Stainless steel and bronze construction addresses corrosion, but at a price. Plastic may address corrosion but can be a disadvantage in making a rugged pump unit.

Also consider the hidden cost of buying a unit that isn’t serviceable and has to be thrown away then replaced with a new unit. All this said, some customers will buy cheap to do one test and that is it. We have always been keen on low corrosion and something that is serviceable with low cost spares.

That’s the philosophy of our manufacturer, Sarum Hydraulics and it has served them and their customers well for 35 years. 

 

Should you buy a hand pump or an air driven pump?

 

An air driven Micropac Duo pressure hydro test pump with built in hand pump on a 50 litre trolley

 

An air driven Micropac Duo pressure hydro test pump with built in hand pump on a 50 litre trolley.

Only if you need to. Hand pumps are low tech and basic. The operator pumps to fill the test system or vessel, builds up the pressure and does the test.

Keep in mind that if you are testing to higher pressure, the hand pump will not pump much per stroke so you will be pumping a long time to fill a large system.

You can get around this by;

-prefilling a system, for example in filling a central heating system with mains water

-using a two speed hand pump where a large displacement /low pressure and small displacement/high pressure pump is integrated into one unit

-using a power operated pump like an air driven pump. The air driven pump will cost quite a bit more money and is relatively complex.

We would suggest that if you have a low pressure test on a relatively small system, the hand pump is an easy choice.

On a large volume system, you should consider faster prefilling using mains water as an option. A neat self-contained solution with an integral 20 or 50 litre reservoir is an air driven pump or a hybrid air/hand like the Micropac “Duo” pump (Sarum-Hydraulics website). 

Prefilling with mains water tee’d into the system works, although do be aware of the need for a WRAS approved check valve to meet Water Regulations then another higher pressure check valve on the feed.

An air driven pump does open up a route to an automated or semi-automated “pressure test rig”, but that is beyond the low budget kit we are talking about here. Talk to us on programmable air driven pressure test units if that is your interest.

 

Do you need a pressure gauge?

 

stainless steel pressure gauge.JPG 

63mm stainless steel pressure gauge on our neat connector for quick removal from a system.

If you are testing, you need some means of knowing the pressure you are generating. If you are working within a quality system, this needs to be calibrated back to a National Standard, so you have assurance that the pressure figure is dependable.

Pressure gauges or indicators include borden tube or capsule ow pressure gauges, electronic pressure gauges or pressure transducers feeding instrumentation. Read our article on how to select the right pressure gauge (Sarum-Hydraulics Website).

You are testing to a pressure and need to know what that was in order to see how much it has dropped after how much time. We like old-tech drag pointer pressure gauges or an electronic pressure gauge that has a “maximum pressure” memory.

 

What is the difference between a hydrostatic pressure test pump and a burst test pump?

 

We would say no difference other than the burst test pump needs some means of recording the maximum pressure reached before the component or system bursts. This can be a drag pointer pressure gauge or an electronic pressure gauge with a “maximum reading” memory.

 

We’ve got a great video of a Micropac pressure test pump in action burst testing

 

 

What size reservoir and material should be specified for a pressure test pump?

 

Some pumps will work with a feed from the low pressure side of a system. We have manufactured Micropac pumps on a skid with a simple hose on the inlet for connection to a supply.

A trough type pump is widely used on cheap pressure test pumps. These might be 5-15 litre. It is easily filled and emptied, makes a low cost reservoir and you can see how much fluid is there. We find them quite awkward to carry and dirt drops into the open trough.

Fixed and portable reservoirs with a filler cap can be easier for carrying around and keep cleaner when left with fluid in them. A larger diameter filler cap makes the tank easier to fill and clean out. Keep in mind that when pump and reservoir reach 20 kg, manual handling becomes an issue.

We suggest to people that they look at a reservoir with an integral two wheel trolley at 20 litres or 50 litre. That can be wheeled around. Cheap pressure test trough pumps might use powder coated carbon steel which has a limited life on water.

Tradespeople often aren’t keen on plastic reservoirs as they can get broken, despite good corrosion resistance. Carbon steel works well on mineral oil. We move to anodised marine grade alloy or 316 stainless for our pressure test pumps. Alloy is light and rugged and worth a thought.

 

Do I need a 316 stainless pressure test pump?

 

A 316 stainless pressure test pump offers enhanced corrosion resistance but at a higher price. Hybrid 316 stainless and anodised alloy meets most requirements.

 

A 316 stainless pressure test pump offers enhanced corrosion resistance but at a higher price. Hybrid 316 stainless and anodised alloy meets most requirements.

Lots of people don’t need a 316 stainless pressure test pump. Some people like the nuclear industry won’t compromise. They need 316 stainless to eliminate galvanic corrosion between dissimilar materials.

We manufacture a full range of 316 stainless pumps. Back in 1983, our big innovation was to use a hard chromed 316 stainless piston rod running in our unique 316 stainless liner.

Couple this with a stainless poppet check valve with a soft seat inlet check valve integrated into our first anodised marine grade alloy test pump.

These have been used for 35 years daily throughout the world. We would say look at a 316 pump, but a good proportion of customers opt for the stainless and alloy unit at a lower price and get a unit that lasts them for their task for years.

 

Do I need a 2 speed pressure test pump?

 

A PSP 2 speed pressure test pump offers a rugged two speed solution.

A PSP 2 speed pressure test pump offers a rugged two speed solution.

 

If your system is low pressure and small volume, you don’t need two speed. Even at low pressure and larger volume systems, you can still live with a single speed pump.

Prefill the system if the pumping to fill the volume is a time consuming. Two speed hand pumps are great where you can use a high displacement up to say 50 bar then switch to a high pressure stage with low displacement but running to high pressure.

Two speed action cuts operator fatigue. If you have low pressure and high pressure tests to perform, the two speed hand pump will perform both using one unit and the minimum of operator effort.

Finally, if you need to replace a legacy Tangye Hydrapak or Hi-Force HMP 2 speed hydraulic hand pump, our PSP unit will retrofit exactly and offer more. Or you may just like this type of hand pump. We do.  

 

Do I need to risk assess what I am doing and write a procedure?

 

It is vital to consider safety, as something failing under pressure can be hazardous. We also suggest planning what you are trying to achieve. So, the answer is yes.

There are good resources on our associated company website;

How to hydrostatic test including a sample procedure,  How to Risk Assess hydrostatic pressure testing and How to create a hydrostatic pressure test certificate 

 

Talk to experts.

 

We can supply anything from low cost trough hydrostatic pressure test pumps for testing pipework through to high pressure two speed pressure test pumps. That’s what we sell on our web site but talk to the experts at Pump Shop Pro on all these requirements plus anything hand pump. Contact us.