Equipment for continuous regulation of the flow rate of fluid in a reciprocating compressor which has a compression chamber with a piston reciprocally movable therein. The compression chamber has an inlet valve and an outlet valve which delivers fluid to a reservoir. A translation device is movable to open the valve and allow closing of the valve. An actuator engages the translation device and includes a rod. The rod has a magnitizable central element located between solenoids of an electromechanical device. The central element is located in a prefixed position with respect to the solenoids under the resilient loading of a resilient device. Detectors are provided for detecting the position of the piston, the pressure in the reservoir and the position of the actuator.