Long lived valves

Often when a satellite is decommissioned there is leftover propellant in the tanks, which should be released to reduce the risk of it catching alight and causing an explosion. Until now this has been done by large pyrotechnic valves, which allow the propellant to escape at the point of decommission.

A de-risk activity with GSTP Element 1 and von Hoerner & Sulger GmbH in Germany have taken the initial idea for the valve which used a bimetal actuator, and adapted it to work with a standard satellite interface. The activity also adapted the materials so that it could be compatible with a range of fluids and gasses where the strength of the valve increased to withstand higher pressures.

The long-life valve is a miniature single shot valve with a bimetal actuator that can perform the task of releasing leftover propellant reliably by simply heating the valve. A proof of concept valve had already been designed and was used as a starting point. The bimetal actuators were gold coated and tested for compatibility with hydrazine (a common propellant), as most bimetals are likely to catalyse its decomposition.

The adapted internal mechanism was tested in a lab setup to ensure the spike successfully pierces the membrane. The pierced membranes were tested to ensure the propellant could flow quickly through the pierced hole.

The lessons learned from all tests were integrated into the design and a flight-like valve was manufactured for further testing. The valve can be used in a wide range of applications where a fluid must be irreversibly released at a specific time. The bimetallic actuator has benefits over a pyrotechnic actuator as it is smaller, cleaner, can be adapted to a wide range of temperatures, gas throughputs and pressures, is highly scalable, and can be repeatedly actuated if necessary.

G617-241TAf closed in 2021.