Abstract: A manual pump includes first and second tubular members. The first tubular member has an upper closed end, a lower open end, and a piston member extending through and mounted movably in the first tubular member. The second tubular member has an upper open end which is fixed sealingly to the lower open end of the first tubular member, a lower closed end, an inflow check valve, an outflow check valve, and two connecting tubes connected to the external face of the second tubular member. Each of the connecting tubes is communicated with a corresponding one of the inflow and outflow check valves.

Abstract: A manual pump includes first, second and third tubular members, and a restraining ring member. The first tubular member has a piston which is mounted movably in the first tubular member. The second tubular member has an upper open end which is fixed sealingly to a lower open end of the first tubular member. The second tubular member further has a first side wall that has first inflow and outflow check valves, and a lower closed end that has second inflow and outflow check valves and a first opening. The third tubular member has a top open end, a bottom constricted end, and a partition. A second opening is formed in a second side wall of the third tubular member. A third opening is formed in the partition. The second side wall has an external thread that is formed near the top open end of the third tubular member. The second tubular member is inserted rotatably into the third tubular member.