A helium dewar, transfer line and pressure gauge connected to an MRI magnet

Why helium matters

The magnet only works because it is cold.

An MRI magnet is superconducting: its coils carry current without resistance only while they sit in liquid helium near absolute zero. Let the level fall far enough and the magnet quenches — the helium boils off, the field collapses, and the system is out of service until it is refilled, ramped and re-shimmed. Watching the level is far cheaper than recovering from that.

Helium level, pressure and boil-off rate recorded at every visit
Coldhead and compressor condition checked against the readings
Vent path, oxygen monitor and exclusion zone verified before work
A written record of the cryogenic state after every intervention

What we do

Four services.
One cryogenic discipline.

Each can be a single visit or part of a maintenance contract. All of them start with the same safety checks.

Helium refill & level monitoring

Transfer from a dewar into the magnet under controlled pressure, with the level, pressure and alarm state recorded before and after. Repeat visits build a boil-off history, which is what tells you whether the magnet is simply consuming helium or losing it.

Coldhead, compressor & cooling

The coldhead and its compressor are what keep boil-off near zero. We check and service the coldhead, the compressor, the helium lines and the water or air cooling behind them — a rising boil-off rate is usually a cooling problem, not a helium problem.

Controlled quench & safety

When a magnet has to be de-energized — for service, decommissioning or an emergency — it is done deliberately, not by accident. Site evacuation, Civil Defense notification, electrical isolation, external vent verification and oxygen monitoring come first; the burst disc is replaced afterwards.

Magnet ramp-up & return to service

After a quench or a magnet move, the field has to be brought back: cool-down, fill, ramp to field and shimming, followed by imaging checks before the system is handed back to the department.

CRYOGEN WORK, PHOTOGRAPHED

On the magnet, on site.

Helium transfers, cryogenic readings, coldhead and compressor checks and service-mode verification on GE and Philips MRI systems — our own photographs.

A GE SIGNA Creator 1.5T MRI prepared for a helium refill

Helium level and alarm readings taken before the transfer

The helium dewar, transfer line and pressure gauge connected to the magnet

Transfer in progress, with the magnet turret and the cooling plant

Coldhead and compressor connections checked during the visit

A Philips MRI magnet with the cryogen dewar and the service screen

The Sun Care team working at the Philips magnet turret

The Philips system service mode used to verify the system configuration

An MRI magnet with its covers removed, showing the cryogenic and service connections

A helium visit

How a refill actually runs.

The same sequence every time, so the readings from one visit can be compared with the next.

Read before you touch

Helium level, pressure, coldhead temperatures and any standing alarms are recorded as found, along with the time since the last fill.
Make the room safe

The external vent path, the oxygen monitor and the magnetic exclusion zone are confirmed before a dewar is brought anywhere near the magnet.
Transfer under control

The dewar is connected, the line purged and the transfer run at controlled pressure, with the level watched throughout rather than filled and left.
Check what caused the loss

Coldhead, compressor and cooling are inspected while the engineer is on site, so a fast boil-off is found now rather than at the next low-helium alarm.
Record and advise

Final readings, the quantity transferred and the expected interval to the next fill are written up, with a recommendation if the trend is wrong.