Liquid supplying device for use in physical and chemical apparatus

A liquid supplying device for use in physical and chemical apparatus, comprising:

• liquid supplying piston pumps each having a cylinder connected to a liquid intake passage and a liquid outlet passage through respective check valves, a piston which moves to and from within said cylinder, and a driving mechanism for operating said piston,
• said liquid intake passages being connected to respective chemical vessels containing liquids, said liquid outlet passages being connected to the physical and chemical apparatus,
• a change-over valve disposed in said liquid intake passages of said piston pumps,
• a liquid discharging change-over valve disposed in said liquid outlet passages of said piston pumps, and
• an automatic controller for controlling said driving mechanisms, change-over valve and liquid discharging change-over valve,
• said automatic controller operating each of said driving mechanisms for the supplying piston pumps so as to fill the cylinder with the liquid from said liquid intake passage in one suction stroke of the piston pumps, and so as to, during one complete discharge stroke of the piston pumps, intermittently discharge an incremental amount of the liquid to said liquid outlet passage, wherein said incremental amount is several microliters,
• said automatic controller operating said piston pumps by turns such that one of the piston pumps is operating to send out the liquid from a respective one of the chemical vessels and the remaining piston pumps are at rest in order to alternately send out the liquids from said chemical vessels to said apparatus.