Thermal Valves & Actuators

Unlike conventional devices, Senior’s thermal actuators and thermal valves use our welded metal bellows technology—which eliminates the need for elastomeric membranes. This approach allows for significant improvements in temperature tolerances, maintenance-free operation and high cycle life.

No Performance Drift

Traditional rubber membranes allow expansion media to leak, so devices experience performance drift—and eventual failure—over time. Our bellows construction means zero leakage of the expansion media, and so our actuators experience no performance drift.

Further, the welded metal bellows is capable of 1,000,000+ thermal cycles offering reliability that is orders of magnitude greater than conventional devices.

Thermal Valves

Thermal valves may also incorporate an integrated pressure relief function, factory calibrated to lift off of the valve seat at the specified “relief” temperature and pressure. The pressure relief mechanism uses a “tuned” spring that is factory-set and never needs readjustment.

Design Fabrication Cost-of-Ownership

The Senior Advantage

  • Innovative – Unique wax-filled design
  • Flexibility – Various wax formulas/actuation temps
  • Safety –   No membranes to fail/replace. Can include pressure-relief options, as needed

The Senior Advantage

  • Withstands harsh environments
  • Compact package
  • Performs in extreme temperatures

The Senior Advantage

  • We “engineer-in” ultimate reliability & extreme performance
  • Extended lifecycles
  • Maintenance-free operation

Product Resources

Thermal Valve/Actuator Design Data Sheet Space Thermal Management Application eVTOL Thermal Management Military Thermal Management


Extended service life from one year to ten

The legacy design for a thermal actuator relied upon an elastomer-encased wax medium. Unfortunately operating temperature extremes rapidly degraded the elastomer, resulting in a very high rate of failure for this device.

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Synchronized Pneumatic Actuation

Our customer was looking to improve the performance of their wafer handling system. Their historical approach involved the use of an air cylinder and a welded metal bellows to seal the penetration into the vacuum chamber.

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