Patented long-life oxygen sensors (3-year warranty, typical lifespan 5-7 years) from Draeger can be used to monitor for oxygen deficiency resulting from helium leaks.
Application – Helium Leak Monitoring with Oxygen Sensors
Extremely cold temperatures are required to operate superconducting coils, in order to generate high magnetic field-strength; to cool the magnets down to superconducting temperatures, cryrogenic liquids are used, which are liquified gases kept in their liquid state at very low temperatures (below 150c).
Helium is a commonly used cyrogenic liquid used in MRI (magnetic resonance imaging) machines in hospitals; in NMR (nuclear magnetic resonance) machines used in bio/pharma research and manufacturing; semiconductor manufacturing; as inert shielding gas in metal arc and laser welding; also as a carrier gas for chromatography.
Although they are non-toxic, cyrogenic liquids still present a danger since they displace oxygen, and a very small amount of a cryogenic liquid can evaporate at room temperature into a large volume of gas. Since Helium and other cryogenic gas are colorless and odorless detecting leaks is critical.
For detecting oxygen displacement, oxygen sensors are used indicating when the ambient concentration of oxygen drops below the normal level of 20.9%. While standard galvanic oxygen sensors work well for this, they need frequent calibration, which is typically every 3 months, and have short life spans (1year warranty, typical lifespan of 9-15 months). They are also subject to drift from environmental changes such as pressure and temperature.