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Barney
Britton wrote...
I
am at the point of finally hooking up my pressurization outflow valve and notice
that it seems to require vacuum to operate as well as the electrical
connections. Does this valve really need vacuum to operate...
Barney,
The pressurization outflow valve does not require
vacuum to operate. The vacuum, if available, pulls the modulator valve fully
open when you select DUMP. The main downside of not using a vacuum source is an
occasional surge in interior cabin pressure during high power settings when the
aircraft is not pressurized. I considered installing the vacuum side of a door
seal pump for this, but decided I could live with the surge to save some
complexity and weight. Have since observed that this can be minimized by leaving
the door seal uninflated until you are ready to
pressurize.
Bob Pastusek
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