Freezing 2nd?
- Thread starter FFMDiver
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In the second stage, the cooling comes from the expansion of air passing through the inlet fitting and valve poppet and will draw heat from any surface that can give up heat to the expanding air.
Consequently the greatest cooling occurs where the air is expanding, usually in the inlet fitting - which is where the orifice and knife edge that seals against the seat is located.
But this still very cold air will chill everything else it encounters downstream until it warms above ambient temperature so areas in the second stage fairly far away from the orifice may stil be chilled below freezing.
Ice in turn forms where ever the surfaces are below freezing AND are exposed to water or moisture in the air. That may mean that ice often forms downstream in the less cold but wet areas of the second stage.
In short, it all depends on the design.
In some designs the ice may form on the lever and the ice obstructed movement of the lever is what holds the very cold but still dry and ice free valve assembly open.
Consequently the greatest cooling occurs where the air is expanding, usually in the inlet fitting - which is where the orifice and knife edge that seals against the seat is located.
But this still very cold air will chill everything else it encounters downstream until it warms above ambient temperature so areas in the second stage fairly far away from the orifice may stil be chilled below freezing.
Ice in turn forms where ever the surfaces are below freezing AND are exposed to water or moisture in the air. That may mean that ice often forms downstream in the less cold but wet areas of the second stage.
In short, it all depends on the design.
In some designs the ice may form on the lever and the ice obstructed movement of the lever is what holds the very cold but still dry and ice free valve assembly open.
