Abstract: A shut-off actuating device includes a stop member biased toward a position where it interferes with the movement of a linkage apparatus of a fluid flow measuring device. The fluid flow measuring device is adapted such that once the linkage apparatus is disabled or rendered inoperative, fluid flow through said device is thereby prevented. A solenoid-operated apparatus is provided which includes a solenoid rod or arm that normally engages the stop member to hold it in a retracted position out of said interference with the linkage apparatus. Once the solenoid apparatus is energized, the solenoid rod is disengaged from the stop member and the stop member is thus allowed to extend into an interfering relationship with the linkage apparatus, thereby disabling said apparatus or rendering it inoperative in order to shut off the flow of fluid through the fluid flow measuring device.