Eccentric backflow preventer

A backflow prevention system, comprising:

• a backflow prevention device, the backflow prevention device comprising:
• a main pipe body extending from an inlet side to an outlet side, the main pipe body comprising a hollow interior defining a fluid passage extending along a first center longitudinal axis from the inlet side to the outlet side;
• at least one check valve disposed within the hollow interior of the main pipe body, the at least one check valve comprising a valve seat fixed within the hollow interior of the main pipe body and a valve member movably disposed on the valve seat between an open position and a closed position, the valve seat defining a valve opening extending therethrough,
• wherein the valve member is configured to move to the open position to permit a flow of liquid through the valve opening from the inlet side of the main pipe body to the outlet side and to move to the closed position to prevent a flow of liquid through the valve opening from the outlet side of the main pipe body to the inlet side;
• an inlet pipe connected to the inlet side of the main pipe body, the inlet pipe defining an inlet flow passage in communication with the fluid passage of the main pipe body;
• and
• an outlet pipe connected to the outlet side of the main pipe body, the outlet pipe defining an outlet flow passage in communication with the fluid passage of the main pipe body,
• wherein the inlet flow passage and the outlet flow passage extend along a second center longitudinal axis,
• wherein the first center longitudinal axis of the fluid passage of the main pipe body is offset with respect to the second center longitudinal axis of the inlet flow passage and the outlet flow passage in a direction perpendicular to the first center longitudinal axis and the second center longitudinal axis,
• wherein a center of the valve seat is offset with respect to the second center longitudinal axis in the direction perpendicular to the first center longitudinal axis and the second center longitudinal axis, and
• wherein the center of the valve seat of the at least one check valve is aligned with the first center longitudinal axis;
• an upstream pipeline in communication with the inlet pipe of the backflow prevention device;
• a first shutoff valve disposed between the upstream pipeline and the inlet pipe;
• a downstream pipeline in communication with the outlet pipe of the backflow prevention device;
• and
• a second shutoff valve disposed between the outlet pipe and the downstream pipeline.