A Filtrine service agent working on a system

The importance of monitoring MR chillers in unprecedented times

September 13, 2021
by John W. Mitchell, Senior Correspondent
A recent article in the Journal of the American College of Radiology urged radiologists to consider what steps they could take to lessen the impact of medical imaging on climate change, cautioning against business as usual. The authors noted that the consequences of climate warming “are disproportionately felt by children, the elderly, those with preexisting conditions and outdoor workers.”

Technical experts working behind the scenes to ensure MR units, and the chillers they run on, remain operational also give thought to this emerging issue.

“HVAC work will continue to be important as global temperatures rise,” said Jason Oliver, service manager for Advanced Cooling Technologies Inc. “One challenge that we have already experienced this year is the wide impact of recent heat waves. These really test all industry technician resources as we get swamped with customer calls.”

He reports that the manufacturer they work with has already raised the operating design temperature range of their newer equipment and added redundant systems within the chiller to provide better performance and reliability in warmer climates.

Under standard service contracts, most MR service providers aren't going to cover chillers and "environmentals,” according to Sean Mykleby, a thermomagnetic and cryogen expert with SouthWest Medical Resources, who agrees that warming trends affect chiller operations. For that reason, he believes proactive real-time, remote monitoring and preventative maintenance are more critical than ever.

“Running sites during warmer weather conditions will always be a detriment to the efficacy of chillers and cooling systems,” said Mykleby. “Looking at the sensor deployments we have on our systems, we can see abnormal cycling on the cooling systems.”

These monitoring capabilities help prevent expensive repairs and downtime for their clients.

However, Mykleby said that he and his team performed more recovery cooldowns during the pandemic than they did in the prior three years. Because many sites went dormant during the unprecedented pandemic and hospitals were focused entirely on saving critically ill patients, many outpatient imaging schedules were curtailed. Often this meant that imaging sites were also unstaffed. Yet power, chiller, and compressor support must still operate regardless of whether or not scanning is conducted. This is a serious problem if remote monitoring is not in place.

“In some cases, staff came back after a 60-to-90-day hiatus, and their MR magnets were completely warm,” he said. “To get it operational again costs about $135,000 and ten to 12 days of downtime.”

Regularly scheduled care and preventive maintenance on cooling equipment is the first defense for avoiding downtimes and expensive repairs.

Tim Confer, president of Northern Air Systems, recalls a shut-down incident in the past year caused by a build-up of cottonwood spores in the coils. The cooling drain pan and the condenser shut down, and condensate leaked, as the spores also blocked the unit drain.

Remote monitoring is one key to ensuring these types of scenarios don’t arise, according to Confer, and to that end it is also essential that sites have adequate network connection and speed to support that monitoring, especially with the transition to the 5G network. The other vital component is preventive maintenance.

“It’s critical to schedule and perform quarterly preventive maintenance (PM), it will save you one day,” said Confer. “Also proactively identify parts during these PMs that are at the end of life so that the technician can replace old components as needed.”

Another vital consideration is putting a backup cooling plan in place for the cryogen compressor, according to Turner Hansel, president of Filtrine Manufacturing This would include facility or municipality water redundancy that can activate in an emergency to prevent an MR quench (catastrophic loss of helium). However, added Hansel, there have been recent advancements with some MR units that are now engineered with helium recovery units. But ultimately, an MR cannot operate correctly without a functioning chiller; it is an integral part of this system as volumes recovered from the initial stages of the pandemic.

“More clinicians are looking for maximum uptime from their MR equipment,” said Hansel. “This has led to more interest in monitoring support systems, like chillers, to cool the imaging equipment. Also, better software systems have been developed to provide easy oversight of the entire imaging and diagnostic system.”

Hansel and the other experts quoted in this article point to high standards for engineering already in place to meet the growing trend of higher summer temperatures. Hansel cited the need for cooling protection from other environmental challenges, such as marine protection and air-borne abrasives such as blown-in dirt.

Oliver, with Advanced Cooling Technologies, described other vital steps that medical imaging sites can take to protect their systems in extreme heat. These include:

• Follow manufacturers clearance requirements around a chiller at the time of installation.

• Place the chiller in a position to, as much as possible, be situated out of direct sunlight.
• Use light roofing colors if a chiller is on a roof.
• If a heat wave is forecast, schedule an extra preventive maintenance on the unit to ensure it's in peak operating condition.
• Make sure that surrounding mechanical equipment is not blowing hot air on the chiller.

Hansel with Filtrine recalled a recent chiller failure caused by both a lack of regular PMs and the location of the chiller. The unit was positioned in a parking garage very close to the vehicle travel lane.

“The vehicle exhaust caused the condenser coil to become absolutely filthy, so much so that it required a monthly cleaning,” he said. “After about nine months of neglect, the chiller was starting to shut down on high refrigerant pressure because the condenser could no longer properly reject the heat. Eventually, this led to other problems with the refrigerant circuit. This could have been avoided with regular preventive maintenance visits and inspections."

And it’s not just the heat — humidity is a problem, too. Mykleby with SouthWest Medical Resources says the dew point comes into play quickly in some locations, such as in Florida. The dew point is the temperature to which air must be cooled to become saturated with water vapor. When air cools to the dew point, condensation appears.

“You might only get water condensation for a few hours each day,” said Mykleby. “But over time, this will become a problem.”

Condensation, he emphasized, is yet another reason to include proactive, real-time, remote monitoring to protect cooling systems. Remote monitoring, he stressed, keeps an MR “alive.” With the price of a helium refill now at about $12,000, Mykleby reports their remote monitoring business grew about 50% in their deployed chillers.

Confer with Northern Air Systems offered a cautionary tale of a site that neglected to keep the recommended replacement parts in stock for emergency repairs. A quench resulted in $40,000 in expenses before the emergency shipment with the part could arrive on site.

Mykleby said a very common service event is when a facility does not have remote monitoring and finds low helium on Monday morning. The coldhead isn’t running, the magnet pressure is high, and the site can’t scan due to low helium levels.

Oliver, with Advanced Cooling Technologies, added that most of their customers' heat wave-associated cooling problems are caused by a single, avoidable problem: dirty condensers. He recommends that preventive maintenance be completed at least twice a year to ensure the chiller is operating within OEM specifications. This, Oliver said, is the best way to protect MR operations during a heat wave.

“We all know that there will be equipment failures, or something will break at some point,” said Mykleby. “A proactive service model gives assurances to the customers that their site will not experience large helium loss and scanning downtime.”