This is quite a deep subject and worth an answer. This is our take after manufacturing this equipment for over 40 years.

A pressure test rig seems to mean different things to our customers. Some see it as a basic carry-around hydrotest and at the other end of the spectrum it is floor standing and operated by a touch screen costing a lot of money. We are going to call a pressure hydrotest pump for a specific job a pressure test rig in this article. Forget images of ultra sophisticated and expensive test equipment for now and let’s focus on what you actually need for the job. You may well end up sophisticated. Let’s try to provide our take on getting from one to the other. Simple and basic to sophisticated.

We’ll put the test medium and pressure to one side. Let’s start with ease of use, productivity and safety.

Can an inexpensive carry-around pressure hydrotest pump be a pressure test rig?

Buy a Micropac MP series carry around hydrotest pressure test pump, spec it up with a release valve and pressure gauge and you have one part of your rig. Buy the trolley version of the MP if you want a 20 litre/5.3USG or 50 litre/13.2USG reservoir as a two wheel cart to wheel around site or shop. We can add accessory equipment:

MP-3 stainless handpump, pressure test rig
TX service cart view of the storage trays hanging off the side of the reservoir

Our Micropac MP-Portable, carry around offers a compact hydrostatic test set and rig up to 700 bar.

Our Micropac TX Service cart forms a basic pressure test rig with an organiser to keep dedicated fittings safe

Add in a hose and a fitting on to the unit to suit whatever you are testing and you have a pressure test rig that can do general or specific jobs. That is your most economic choice and will last for years.

If you have a dedicated fitting or set of adaptors for your job on site, look seriously at the TX two wheel service cart with an integrated storage tray and document storage. That starts to look like a pressure test rig for very specific testing jobs, where the dedicated fittings or custom adaptors stay with the rig. Our experience is that unless you look after these parts, testing productivity is a disaster, with people searching for fittings every time it is used.

Can I use an air driven pump in my pressure test rig?

Yes, for the right application, we like air driven pumps for pressure hydrotesting. Care needs to be taken on circuit design and what you are trying to achieve. We can offer easy and cost effective solutions. You are simply investing a little more to make your pressure test rig more sophisticated and best suited for your job.

Up to now, we have discussed your pressure test rig as a simple and cost effective carry-around or service cart with its hand pump head, a hose and specific fittings or adaptors. Are you finding pre-filling of the test specimen with the test fluid quite slow or labour intensive? Look at our DUO pump which in one compact cart integrates our Micropac hand pump and a very neat air driven pump. The air pump operating pressure is set on the integrated regulator. Use 100% air driven pump for deskilled and fast operation or use the hand pump for final pressure top up or when there is no shop air supply available. This is a very neat pressure test rig unit.

Solutions are available with 100% air driven pump and no hand pump. The MP- two wheel cart trolley and TX two wheel service cart with organiser for fittings and documents can be supplied with just the air driven pump. An air driven pump can also be mounted on a skid in our PTR-M. Our experience is that air driven pump units seem to home in on the precise application and customers start to modify a unit for a task rather than have a general pressure test rig. You might have extra pressure ports or a specialised pressure gauge.

How do I make my pressure test rig safe to use?

This is an over-riding need, not an option. Even the simplest carry- around needs to be used safely.

a polycarbonate safety enclosure for pressure testing vessels inside

Our MTE Test Enclosure for safety during pressure test

Follow simple instructions for safe use of a hand pump. If you are pressure testing a work piece, do risk assess what happens if it leaks or bursts. Make a cover for the test piece or consider our MTE test enclosure that provides some protection. There is an enhanced ballistic protection chamber in the range as well. You shut the clear door on the chamber before operating the hand pump. This option is the most cost effective pressure test rig incorporating a test chamber. Investing in safe kit is a must.

Do I need an interlock on the test chamber door for safe operation of my pressure test rig?

You need to risk assess this. Could somebody set the rig running up to pressure with the door open? Not if it is a hand pump.

We don’t get involved on electric pressure test rigs, as you inevitably have complication. If the deliverable is a rig using a press button operated electric pump and test chamber, you must use an interlock to ensure that the pump cannot be operated with the door open.

If your pressure test rig uses an air driven pump operated by a button or lever, we would say the same is true. If you have a safety test chamber, you can’t have the door left open. You need an interlock. Some customers achieve a simplified interlock using a ball valve to obstruct the door and ensure that it is always shut.

A hand pump is purely manual.

How can I speed up my pressure testing as my pressure test rig is slow?

The simple answer to speeding up pressure testing using your pressure test rig is to invest more in it to make the process more productive. But how much?

This is the most difficult question to answer. Our starting point is to use dedicated fittings and keep them safe on our TX service cart. That helps. Once you are talking production pressure testing, people very often do end up with an expensive custom pressure test rig. You might design a clever fixture that clamps a component down onto a manifold with pressure ports using toggle clamps to remove the need for threaded connections. It all comes down to numbers and how many you are testing. Is there any in-between to speed things up? Yes, there are solutions that we like.

How can I speed up hydrostatic pressure testing using my pressure test rig without spending a lot of money on a sophisticated fixture?

Over many years, our customers have used a few hacks to speed up pressure testing during batch production. Laborious pressure testing is hard work. Especially once numbers are involved.

Consider testing numerous parts at the same time if it works for you. That needs thinking through. We often suggest buying a few quick disconnect couplings. We are sentimental about Parker Snaptites after 40 years, but there are numerous ranges that are good. Use the coupler on the end of the hose and the cheaper male probes on your test piece. Quick disconnects do eventually wear out and leak, so keep that in mind. A more expensive option is threaded instant test couplings from WEH. The threaded adaptor shrinks whilst being inserted in the female port then is expanded again to seal. They are widely used.

The next step is custom fixtures to speed up connection and removal. Pressure connections might seal using o ring seals. Every need is different. A pressure test rig builder and designer will sort out their proposal.

How do I automate the testing process with cycles of pressure up and down?

To pressure test in pre-programmed cycles is very much higher end pressure test rig territory. The starting question is what do you want to achieve? There is a solution for simple pressurise/depressurise cycles repeated again and again.

an automatic pressure test cycling rig with touchscreen

Our PTR-A automatic pressure test rig

For example, if you wish to pressurise a workpiece to 400 bar for 20 seconds, hold for 90 seconds, release the pressure for 10 seconds to ensure it is at zero, dwell for 10 seconds before starting again and repeat this 3K times, we can supply you our PTR-A benchtop automated pressure test rig. You programme it using the intuitive touch screen and there are safeguards built in like stopping the cycle if something is leaking and has not reached pressure after so many seconds. This is a cost effective solution and suitable for multiple fluids including water. The PTR-A programmable pressure test rig is a catalogue unit. Users have found them a great solution for high cycle fatigue or creep pressure testing for components including automotive fuel tanks, consumer item like radiators and more specialist parts like composite pressure vessels for aerospace.

Move to specifying a rig that will ramp up and vent down pressures at a programmed rate and you are into much more specialist territory. Similarly, if you are requiring multiple test stations powered from one pump. Go to a traditional custom pressure test rig manufacturer like Comar. A common formula seems to be to use your in-house instrumentation Engineer to programme a rig. All we would suggest is that the valves to ramp up and down pressure in a controlled manner are a lot more exotic than our simple pressure release valve that is open or closed. There is cost in sophistication.

You have been talking about fluid pressure test rigs. Can I use a pressure test rig running on shop compressed air or higher pressure gas?

We have been talking fluid hydrostatic pressure testing. Talking about fluids that flow rather than just liquids, compressed air from your shop supply might be the most widely used medium in industry. On the face of it this is very simple, but safety is still paramount. Lots of people do use sophisticated test rigs using shop air, for example plastic moulders. This isn’t our thing. We prefer to test on water.

Higher pressure gas is used for testing, but we think it is highly specialist. It isn’t our thing at all. All pressures can be hazardous. High pressure gas is particularly so.

What is the answer to whether a pressure test rig for hydrostatic pressure testing will cost me a lot of money? Is a pressure test rig expensive?

The simple answer is that we can supply you a simple value pressure test rig that will do a range of jobs, day in and day out. We can supply cost effective safety chambers. We can help you simplify testing and be more productive up to a point with a modest additional investment. We can supply our cost effective catalogue programmable cycling test rig for bench top. An ambitious stand-alone test rig can cost a lot of money from a custom rig manufacturer. There is a lot of work in one. Buy experience to achieve what you require. Comar are one supplier that we know over many years.

Be clear on what you require of your pressure test rig or hydrostatic pressure test pump. The result is what counts. After over 40 years of manufacturing our Micropac pressure test rigs and hydrostatic pressure test equipment, we are the experts. Talk to us about your next requirement.

large testing rig three quarter view

Sophisticated Pressure Test Rig for an aerospace customer from experts Comar