CONTROLLER OF NUMBER OF TURBO COMPRESSOR

PURPOSE:To constantly control force-feed pressure by detecting force-feed flow rate to load from a common discharge piping for connecting to compressive medium discharge load sides of a plurality of turbo compressors, and selecting the number of machines to be driven according to the detected flow rate. CONSTITUTION:Respective turbo compressors 10, 20, 30 suck atomosphere by suction throttle valves 13, 23, 33, and forcibly feed it by main bodies 14, 24, 34, and pressure-detect it by pressure controllers 16, 26, 36 and control the suction throttle, valves 13, 23, 33 according to the load fluctuation. And it forcibly feed the atmosphere to the load through a common discharge pipe through the respective check valves 17, 27, 37. Two flow meters 2 are interposed in this discharge piping, so as to detect the flow rate in the discharge piping and input in the number control board 1. The number control board 1 determines the number of machines to be driven according to the detected flow rate, and outputs the starting/stopping command to respective machine side boards 11, 21, 31 so as to control them.