Compact cryogenic valve from STÖHR with integrated pneumatic actuator
Typical cryogenic valves on the market are space consuming due to their
large distance between the actuator and the medium. Conventional actuators
lose power when they are exposed to temperatures below -40 degrees
Celsius. Conventional cryogenic valves are therefore designed with long valve
body and stem to position the actuator as far as possible from the cryogenic
medium to avoid freezing as well as condensation. This leads inevitably to
increase of height to almost double.
With its actual development FREES compact, STÖHR ARMATUREN developed
a very compact valve with integrated actuator achieving various
advantages:
- pneumatic drive suitable for use in cryogenic applications
(up to -196 degrees Celsius),
- maximum possible height reduction,
- total weight reduction,
- smaller footprint of the actuator,
- unrestricted fitting position in vacuum-insulated pipes, i.e. installation
upside-down, also for the pneumatic actuator.
The 6-bar industry standard for the operating pressure of pneumatic valves
could be retained. Also maintainability of valve stem and actuator were
achieved which means easy installation and removal of actuator and valve insert unit is possible without opening the vacuum system.
Change of actuator can be performed without opening the media space which means that no system downtime is required. In
addition, life cycle of the pneumatic actuator was significantly extended by replacing O-ring seals with bellows instead. Overall, by its
compact design a lower use of material could be achieved.
For the prototype a number of different ideas were implemented, for example using the dead space for functional units, avoiding
long valve stems, replacing stainless steel components with alternative materials, using stainless steel pneumatic cylinders of variable
length as well as separating of mounting and sealing forces.
New features are the replacement of heat-transmitting stainless steel components by special cryogenic-grade plastics including pressure
and force transmitting parts in cryogenic areas such as the valve stem. In addition minimized frictional forces and an overall low-wear
design were achieved.
The newly developed FREES compact technology demonstrator is shown at the VALVE WORLD 2012 in hall 3 on stand A82
of STOEHR ARMATUREN.