Redwood microvalve operation

The Achilles heel of the AIMS system was the Redwood microvalves that were used for positive flow shut-off Failures generally occurred when the system was first powered up, which suggested that power transients were the cause of many of the problems. Specifically, these valves were thermally actuated, so opening one of the SOVs produced a large transient current draw of about one amp, but for less than % second. Adjustments were made in the LabVIEW control program to prevent the simultaneous actuation of multiple valves. In particular, the valves were not allowed to actuate when power was first applied to the chassis. 

Another difficulty was that the normally-closed valves SOVs would sometimes fail to open when actuated. This was traced to an inherent design issue, so it was necessary to simply replace the Redwood flow manifold with another manifold. Fortunately, some spare manifolds had been ordered that could be used while the components were repaired by Redwood. 

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The American company Redwood MicroSystems offers thermopneumat-ically operated microvalves for gases. Both normally open and normally... 

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