PREH’s ingenuity solves MRI chiller problems

15 June 2018 - Mike Sullivan - Companies on the Move
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AN AUSTRALIAN company’s determination to solve expensive MRI machine failures could change the way these vital medical machines are maintained nationally and, eventually, globally.

Heating, ventilation and air conditioning services group PREH – an acronym for project management, refrigeration, electrical and HVAC – has spent the past two years designing, developing and proving its own chiller set-ups for medical magnetic resonance imaging (MRI) machines.

PREH designed units – which feature two complete compressor systems in the chiller instead of the usual single – are also now being used for data centre cooling.

Failures of chiller units – vital for the operation and integrity of MRIs – are one of the main causes of MRI unserviceability. When a chiller unit fails, the vital helium gas that enables the MRI unit to scan can leak out. That helium gas is very costly to replace.

For the medical centre dealing with a ‘down’ MRI, the impact extends beyond simple loss of revenue. It can cause problems for patients who may be in urgent need of an MRI scan – and may even trigger patients to seek alternative practitioners. 

“An MRI is a $5 million device,” PREH managing director Gavin Bailey said. “It has helium in it as a super conductor. It runs at minus-275 degrees celsius.’

Major technology companies such as Siemens, Phillips, Toshiba and GE make the hi-tech MRI systems, but chiller units are supplied and maintained by Australian companies utilising a variety of compressor systems. After PREH repaired several chiller units from another company that had a history of failure – and initiated a maintenance program over many months that brought them close to perfect reliability –  Siemens Health approached Mr Bailey and his team to see if a similar result could be achieved on chillers attached to Siemens systems Australia-wide.

Mr Bailey – a former technical manager with refrigeration appliances group Fisher and Paykel, at manufacturing plants in New Zealand and at Cleveland, Queensland – looked at the performance data of existing chiller set-ups and realised a re-design of both the equipment and the maintenance regime had to take place.

“We looked at all these chillers and we thought, this is really not the right equipment for the job,” Mr Bailey said. “It was like trying to tow a trailer with a Mini. It was a good product, just not designed for that.”


Mr Bailey defines PREH as a “risk management company with regard to your cooling services”. It is an out-of-the-ordinary service company that has developed its own service management software to maximise the value of preventative maintenance. PREH now markets this cloud software platform, CatchData, to other service companies (see Business Acumen issue #90).

“Whether it is a data centre, a medical practice, or an industrial site, we look at the risk to the business and that is how we design,” Mr Bailey said. “We don’t design to a number, we do not design to a cost, we design for the risk … and then we work it from there. It is risk plus cost, but risk is our main focus.”

That was how PREH approached the challenge of getting MRI chiller units – starting modifying the most popular Aquacore version – up to extremely high reliability factors.

“Siemens Health brought me in because they had a lot of these Aquacores and they had a lot of issues with the maintenance … and perhaps the mindset of the service company that was looking after them,” Mr Bailey said. “We have been quite a leader in Queensland in this area and we know the Aquacore off by heart.

“The reason we actually got the contract was that we could give (Siemens) a consistent outcome, both in paperwork and service. CatchData enabled us to give the same result each time, no matter if it was ourselves or a subcontractor (doing the work) or not.

“Our expertise and our technical support on the chillers resolved all the issues.”

As PREH solved the immediate problems of MRI downtime due to chiller problems, it became obvious that a better chiller design that had greater redundancy and was easier to maintain was the goal. The PREH team set to work, building in better componentry, operational software, and ease of fitment and maintenance.

“Downtime was a big thing. A big issue,” Mr Bailey said. “Obviously it was a big cost for these guys.”

The real innovation was in designing a pair of systems within the one chiller unit, eliminating the large power fluctuations that promoted stress on components.

“What we have done now is to install two chillers that are 40kW each (per MRI) for the same price as one,” Mr Bailey said. “We have achieved outstanding results with it.

The biggest benefit is that one of the units will comfortably run an MRI, so the second is designed to kick in should the first unit fail completely or an environmental need eventuates. The second unit comes in seamlessly, so an operator is only aware of a problem from a warning light. PREH is then notified of a problem for immediate maintenance.

“A technician can then be notified. And the machine is still operating. That’s the beauty of our system.”


The energy used by an MRI can vary greatly depending on the type of scan undertaken and the weight of the patient. Simply, the bigger the patient, the more molecules being scanned.

An MRI unit magnetises all the molecules in a patient’s body. It then takes a snapshot image. 

“The more intense the scan and the bigger you are, the more grunt it needs,” Mr Bailey said. “They use a lot of power to do this as the heat generates and increases quite quickly.

“We did some experiments and monitored this process for about four years. We believe it goes from about 10kW to about 35-40kW, at most. So that was the magic number.

“So we went, wait a minute, we can build redundancy in. So you have now got 40kW of chiller on tap, plus a back-up.”

Each circuit in the chiller unit contains one controller, one pump, and one refrigerant circuit that has four stages of cooling.

“That means it doesn’t turn off and on as much and it is a lot smoother. You don’t have the highs and the peaks. And the other unit is not running. You are saving energy. Plus you have got redundancy. If one fails, the other one will take over.”

Most (older) chillers just turn off or on and were often up to 60kW units, utilising a single compressor.

“Because there is too much (switching) off and on, when refrigeration stops it still keeps the system continues boiling … so it still needs to remove heat,” Mr Bailey said. “Ideally the compressor should run for about 15 minutes, but many existing chillers are running for only 2.5 minutes. That is not even within the warranty specs of the unit. The power is seven times the start-up current. It’s just an ineffective formula.”

There were other problems with the old design that PREH had to resolve.

One serious issue – the chiller housing design – was actually an occupational health and safety problem. PREH’s new design of the chiller housing changes the way air flows and actually makes the unit safer to work on.

“We have removed an OH&S issue,” Mr Bailey said. “In most old chillers the airflow goes in and up through some fans. You have an issue because if that fan fails you cannot remove the side because of that air path … You can’t do any electrical work to it because you have another spinning fan – and you have to turn that off and shut down the whole system.

“So we solved that issue with our new chiller units. You can now maintain it because you do not have to turn off a master fan. Because it is two units, you can turn one off totally, to work on it, and you have the other one still operational. One is enough to maintain the MRI’s needs.”

PREH has developed five different installation and configuration styles for the chiller.

That re-design is all about the making the most of the optimum footprint available at different sites. The different chiller types move componentry around and blow air in different ways. There is even one chiller that blows in two different directions.

“They may be a little bit bigger than the one they replace, but that is all about the clearances around them, because you need that serviceability space around that area,” Mr Bailey said.

“That’s why the redundancy is good, as you can turn one off and work on it safely, without interrupting their services. It’s like, how are you going to change a fanbelt in a car when it is running? If you had two engines, a guy could sit in the back and fix that one while the front one is still operating the vehicle.”

PREH’s design uses two pumps, for redundancy, and two refrigerant circuits and printed circuits.

“We looked at getting such a system manufactured from Europe and it was cost prohibitive,” Mr Bailey said. “So we looked at engineering this system ourselves and looked at all the benefits and went, … We can actually do this for the same price as one. And the two systems talk to one another.”


PREH got its chance to test its new unit on an MRI unit at a surgery in Gympie.

“We came across a (compressor) unit (a Schneider brand) that was very competitive and it was quite intelligent,” Mr Bailey said. “And the price was really good.  We thought, let’s see if we can get this right. We looked at the engineering side of it and realised the solution was going to work.

“A doctor in Gympie let us test it and we had to give some pretty big guarantees. We said we would pay to remove and replace the chillers if they were unsatisfactory, at our cost.”

Mr Bailey said the Gympie surgery MRI happened to be a GE site. The results of PREH’s new system have been spectacular.

“We now comprehensively cover that chiller for GE and that maintenance contract is through GE now,” Mr Bailey said.

“We have had three sites installed for two years and now the trust is there in the market. Nationally, we are up to about 14 sites. We have a lot in Melbourne and have a lot of proposals in train in Sydney. Just waiting for green lights. We have had no downtime to date. Zero. So we have achieved our goal.”

Furthermore, Siemens has given PREH a three-year contract on installing the new chillers, Mr Bailey said, “and now that’s all they buy”.


PREH resolved two distinct challenges for Siemens in Australia.

First, Siemens at the time had about 51 chillers in the market that were giving reliability challenges. These were all from one particular Australian manufacturer who was mixing and matching componentry so that hardly any of these chiller units were the same. They failed regularly and PREH had to make those chillers reliable for Siemens, as a matter of urgency.

“That’s what we have achieved and we are at 100 percent uptime at this stage,” Mr Bailey said. “We are pretty proud of that. There are still a few little things we are tweaking, of course.”

PREH’s own goal for Siemens was to remove all risk of helium loss and downtime on their MRI chillers.

“The biggest thing, environmentally, is the loss of helium,” Mr Bailey said. “Helium costs a hell of a lot and it is finite (on earth). At the moment, the estimated quantity of helium is depleting. Helium is one of the only gases that, when it is released, goes out into space … it does not stay down in the atmosphere. It can actually go through glass, that’s how fine it is.”

Mr Bailey said a major impact on the helium market came from the crash of the Hadron Collider system in Switzerland several years ago.

“The Hadron Collider is essentially a collection of MRIs, similar technology,” he said. “They have five clinch on the cooling system, which means the system says it is unstable and is boiling off and shuts itself down. It can actually destroy itself. There is a risk of it cracking. Then it just lets everything go. Five or six of them let go a few years ago and this caused a major helium shortage in the world.”

The other Siemens challenge to PREH was that they wanted electronic consistent reporting.

“And it was our CatchData software that landed me the job,” Mr Bailey said.

CatchData was able to supply much-needed data and insights into Siemens’ client maintenance programs nationwide – and this was an advantage Siemens had been seeking for several years.

“It’s amazing how these two different areas of our business came together in this way,” Mr Bailey said.

You can see a lot through MRIs, Gavin Bailey said, but he was surprised to find that MRIs showed him the future for PREH.

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