Methods, apparatus and/or systems relating to controlling flow through concentric passages

An annular dual-flow check valve for controlling the flow through concentric channels that have a common outlet, comprising:

• an outer body and an inner body that define the concentric channels, which include an outer channel and an inner channel formed therein;
• a spring activated annular poppet that resides in the outer channel and has a range of motion in the axial direction;
• and
• an opening through the inner body that connects the outer channel to the inner channel;
• wherein:
• the axial movement of the annular poppet is regulated by the extent to which the pressure of the flow upstream of the annular poppet in the outer channel depresses the spring by pushing on the annular poppet;
• the axial range of motion of the annular poppet includes at least two axial positions:
• a closed position where the annular poppet substantially covers the opening and a open position where at least a portion of the opening is not covered by the annular poppet;
• and
• the spring and annular poppet are configured such that:
• when the level of pressure of the flow upstream of the annular poppet is below a first predetermine pressure level, the annular poppet resides in the closed position;
• and when the level of pressure of the flow upstream of the annular poppet is above a second predetermine pressure level, the annular poppet resides in the open position.