Expansion tank with double diaphragm

An expansion tank, comprising:

• an outer shell;
• a bladder disposed within the outer shell;
• wherein the bladder comprises a non-flexible diaphragm having a peripheral edge and a flexible diaphragm having a peripheral edge, wherein the peripheral edges of the non-flexible diaphragm and the flexible diaphragm are sealed to one another to form a circumferential seam, and wherein a space within the bladder is fluidically isolated from a space between the bladder and the outer shell;
• and
• an insert disposed in the outer shell, the insert at least partially defining a path for water to flow into the bladder from outside the tank,
• wherein at least a portion of the outer shell is injection molded around the insert.

A flow-through connector for a diaphragm tank comprising a bladder having a non-flexible diaphragm and a flexible diaphragm, the flow-through connector providing a path for water to enter the bladder through an orifice in the non-flexible bladder, the orifice defined by an edge of the non-flexible bladder, the flow-through connector comprising:

• a nipple having first and second ends, the first end comprising a plurality of tabs,
• wherein the tabs are manipulable between an insertion position and a securing position to secure the nipple to the non-flexible diaphragm;
• a first retainer ring fixedly attached to the nipple such that the first retainer ring is disposed outside the bladder when the flow-through connector is installed;
• a second retainer ring having slots configured to receive the plurality of tabs;
• and
• a grommet sized to fit around the nipple between the first and second retainer rings and comprising a groove adapted to receive the edge of the non-flexible diaphragm,
• wherein, in the securing position, the tabs press the second retainer ring towards the first retainer ring to create a seal preventing fluidic communication between an interior and an exterior of the bladder and between an interior of the bladder and a space between the first and second retainer rings.

A diaphragm tank comprising:

• an outer shell;
• a bladder disposed within the outer shell and comprising a flexible diaphragm and a non-flexible diaphragm, the non-flexible diaphragm having an orifice defined by an edge;
• and
• a flow-through connector, the flow through connector comprising:
• a nipple having first and second ends, the first end comprising a plurality of tabs,
• wherein the tabs are manipulable between an insertion position and a securing position to secure the nipple to the bladder;
• a first retainer ring fixedly attached to the nipple and disposed between the non-flexible diaphragm and the outer shell;
• a second retainer ring disposed about the nipple and within the bladder;
• and
• a grommet disposed between the first and second retainer rings and comprising an annular u-channel disposed about the edge of the orifice in the non-flexible diaphragm,
• wherein, in the securing position, the tabs press the second retainer ring towards the first retainer ring to create a seal preventing fluidic communication between an interior of the bladder and a space between the bladder and the outer shell and a space between the interior of the bladder and a space between the first and second retainer rings.