Abstract: To provide a technique capable of facilitating water quality sensor calibration and drainage operations for improving water quality even when water quality monitoring devices and drainage devices are installed in places where operation is difficult, such as inside manholes. In a case of a deviation between a manual analysis value obtained at a water quality monitoring device (water quality sensor) installation site and the water quality measurement value (e.g., residual chlorine concentration) measured by the water quality monitoring device, a calibration value obtained based on the manual analysis value is stored in a cloud database via a communication terminal (communication unit) and network, and the water quality monitoring device downloads (acquires) this calibration value, and calibrates the water quality sensor based on the calibration value.

Abstract: An automotive radiator cooling system has a radiator cooling fan driven by a hydraulic motor actuated by a pressurized fluid fed through a hydraulic circuit from an engine-driven hydraulic pump. A bypass line extends in bypassing relationship to the hydraulic motor and has ends connected to the circuit upstream and downstream of the hydraulic motor, respectively. A check valve is provided in the bypass line and is operative to allow a flow of the fluid from a reservoir through the bypass line back into a part of the circuit upstream of the motor only when a pressure drop takes place in that part of the circuit due to free rotation of the cooling fan, and thus of the motor, independently of the drive by the hydraulic pump. The backward flow of the fluid is operative to compensate for the pressure drop to prevent the occurrence of cavitation in the circuit upstream of the motor. Desirably, the bypass line is incorporated into the housing of the hydraulic motor.