Cryogenic valves for liquid hydrogen, liquid helium and other low-temperature fluids must simultaneously satisfy demanding requirements for external leak tightness and thermal isolation. Conventional cryogenic valves commonly address external sealing and actuator thermal isolation through extended bonnets, vapour columns, long stems and/or bellows-sealed linear architectures. These approaches are proven, but they add mass, increase installation volume, restrict orientation, introduce conductive heat paths into the cryogenic region and limit the use of high-flow compact quarter-turn valve types.
This presentation describes the application of Actuation Lab’s novel stemless ball valve technology to cryogenic service, with particular emphasis on liquid hydrogen systems for commercial aviation. The technology was originally developed to eliminate fugitive emissions in industry by removing the valve stem and associated dynamic wear seals to atmosphere. Instead of transmitting torque through a mechanical shaft and packing seal arrangement, the stemless architecture uses non-contact magnetic or electromagnetic means to impart torque into a fully sealed valve body, preserving a hermetic pressure boundary while enabling external actuation. In cryogenic applications, this same architecture enables compact, high-flow ball valves with hermetic external sealing, reduced or eliminated extended bonnet/vapour-column requirements, greater orientation flexibility, and lower parasitic heat ingress by removing the conductive valve-stem path.
Here we present cryogenic valve designs currently in development for aircraft fuel-system applications. These designs exploit a compact, high-flow ball-valve architecture to reduce installation envelope and chill-down mass relative to conventional alternatives, while maintaining a fully sealed pressure boundary. A mass and packaging comparison will be provided against representative bellows-sealed and extended-bonnet cryogenic valve technologies, highlighting the system-level implications for aircraft integration, where every kilogram of hardware and every additional installation constraint carry a performance penalty.
Thermal modelling results will also be presented to quantify the design trade-off between compactness and heat ingress. The analysis explores the bounds imposed by vacuum jacket and insulation geometry/location, and valve maintainability/accessibility, on thermal performance.
Finally, experimental results from helium (6 bar) seat leak testing at 77 K will be presented. Testing has been used to quantify achievable internal seat leakage and to examine how leakage changes with cryogenic cycling and wear of the seat/ball interface. Preliminary testing has demonstrated seat leakage as low as 3 × 10?? mbar·L·s?¹
The presentation will close by discussing the development steps required to extend this performance towards liquid-hydrogen and helium temperature.

Keywords
ball valve|thermal ingress|magnetic|leakage