Abstract: A flow control device insertable into a pressurized fluid line upstream of the fluid utilization device for automatically terminating the flow thereto upon the occurrence of any one of a number of predetermined conditions, such as a leakage in or to the utilization device, an excessive quantity of the fluid supplied to the utilization device, and/or the supply of the fluid at an excessive rate to the utilization device. The control device is electrically controlled by a power supply which is normally disconnected from the control system and is connected thereto only when there is flow to the utilization device, so as to conserve the energy of the power supply when no fluid is flowing to the utilization device.