A device measures the flow rate of a fluid, such as concrete, in a pumping plant connected to a drilling machine provided with a drilling tool. The pumping plant includes a motor pump and a connection pipe to lead fluid from the motor pump to the drilling tool. The device includes a transmitting module, for rigidly and removably mounted on the pumping plant and including an accelerometer and a receiving module, associated with the drilling machine. The transmitting module detects accelerations generated by vibrations of the pumping plant during the pumping of the fluid. The accelerations indicate flow rate of the fluid. The transmitting module wirelessly sends a signal, which is processed based on the detected accelerations, to the receiving module. The receiving module receives the signal from the transmitting module and sends a signal indicating the flow rate of the pumped fluid based on the received signal.