Apeks technical informatiom
30 May 2020   

Apeks Technical - First Stage Operation APO525

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Dry-Sealed Four Port 1st Stage

In the unpressurised state, the H.P. valve is held in the open position by the large spring. High pressure air enters through the filter in the inlet connection and flows through the valve seat orifice to the medium pressure side. When the pressure builds to 9.5 bar, it exerts enough pressure on the primary diaphragm to compress the large spring. This allows the small spring to close the H.P. valve. This medium pressure of 9.5 bar is constant, regardless of cylinder pressure. This is achieved by means of a counter balance chamber of similar area to the valve seat orifice.

When the diver inhales, the medium pressure air (9.5 bar) acting on the primary diaphragm drops, allowing the large spring to push the diaphragm which in turn pushes the H.P. valve off it's seat. This allows more air to flow from the high pressure side and the air continues to flow until the diver stops inhaling. The pressure then builds up to 9.5 bar, compressing the large valve spring allowing the H.P. valve to close again.
As the diver decends, the demand for air increases. To help maintain the supply, the medium pressure is always 9.5 bar above ambient. In the Apeks Dry-Sealed System, this is achieved by allowing hydrostatic pressure acting on the secondary diaphragm to be transmitted to the primary diaphragm via the load transmitter. This Dry-Sealed System makes this 1st Stage ideally suited for use in Extreme conditions.

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