Patent ID: 7374409

Claim:
A reciprocating pump including: a pump body comprising a suction passage and a discharge passage for a to-be-transferred fluid; a diaphragm which is air-tightly fixed to said pump body to form a closed space; a reciprocal driving device which drives said diaphragm to expand and contract in an axial direction of said pump body, thereby increasing and decreasing a capacity of said closed space; a plurality of first spring-type check valves having a spring comprised of a fluororesin material which are disposed between said suction passage and said closed space, and which, when the capacity of said closed space is increased, allow only a suction flow of the to-be-transferred fluid that flows in a suction direction from said suction passage to said closed space, each of said first check valves having a pressure receiving area that is smaller than a passage cross section area of said suction passage, said first check valves causing said suction passage to communicate with said closed space; and a second check valve comprised of a fluororesin material which is disposed between said discharge passage and said closed space, and which, when the capacity of said closed space is decreased, allows only a flow of the to-be-transferred fluid that flows in a discharge direction from said closed space to said discharge passage, wherein said suction passage communicates with said closed space via said first check valves having a pressure receiving area that is smaller than a passage cross section area of said suction passage, and the total pressure receiving area of said first check valves is equal to the passage cross section area of said suction passage.