Apparatus, system, and method for a self-venting drain valve

A system to separate and drain water from a fuel, the system comprising:

• a fuel-water separator;
• a self-venting drain valve comprising:
• an inner drain body disposed on the fuel-water separator;
• an inner liquid outlet in a lower portion of the inner drain body;
• an air inlet disposed at a radial offset from the inner liquid outlet and above the inner liquid outlet, the air inlet having a cross-sectional area smaller than a cross-sectional area of the inner liquid outlet;
• an outer drain body disposed around and below the inner drain body, the outer drain body adjustably coupled to the inner drain body;
• an outer liquid outlet in the outer drain body, the outer liquid outlet disposed substantially below the inner liquid outlet;
• a lower seal disposed below the inner liquid outlet and between the inner drain body and the outer drain body, the lower seal engaging a lower sealing surface;
• and
• an upper seal circumscribing the inner liquid outlet and the air inlet, the upper seal disposed between the inner drain body and the outer drain body, the upper seal engaging an upper sealing surface that extends further beyond the upper seal than the lower sealing surface extends beyond the lower seal,
• the self-venting drain valve being arranged in connection with the fuel-water separator so as to include a fully closed position, a partially open position configured to allow draining the water in the fuel-water separator under pressure from a pump, and a fully open position to allow venting air through the air inlet for draining the water in the fuel-water separator under atmospheric pressure.

A self-venting drain valve to drain a liquid from a fuel-water separator, the self-venting drain valve comprising:

• a substantially cylindrical inner drain body formed in a container wall of the fuel-water separator;
• an inner liquid outlet in a lower portion of the inner drain body;
• an air inlet disposed at a radial offset from the inner liquid outlet and above the inner liquid outlet, the air inlet having a cross-sectional area smaller than a cross-sectional area of the inner liquid outlet;
• a substantially cylindrical outer drain body disposed around and below the inner drain body, the outer drain body threadably engaging the inner drain body;
• an outer liquid outlet in the outer drain body, the outer liquid outlet disposed substantially below the inner liquid outlet;
• threading disposed on an exterior portion of the inner drain body and corresponding threading disposed on an interior portion of the outer drain body, the threading configured to adjustably couple the outer drain body to the inner drain body;
• a lower O-ring seal circumscribing a portion of the inner drain body extending below the inner liquid outlet, the lower 0-ring seal engaging a lower sealing surface disposed on an inner face of the outer liquid outlet;
• and
• an upper O-ring seal circumscribing a portion of the inner drain body above at least a portion of the air inlet, the upper O-ring seal engaging an upper sealing surface disposed on an inner face of the outer drain body, the upper sealing surface extending further beyond the upper O-ring seal than the lower sealing surface extends beyond the lower O-ring seal,
• the self-venting drain valve being arranged in connection with the container wall so as to include a fully closed position, a partially open position to allow draining the liquid under pressure from a pump, and a fully open position to allow venting air through the air inlet for draining the liquid under atmospheric pressure.