Abstract: Arrival of a pressure wave front is detected at a plurality of monitoring stations spaced along a protected section of a fluid-carrying pipeline. Arrival times obtained at the monitoring stations are qualified as to whether they correspond to a pressure transient event (critical event) which originated in the protected section. If so, the location, amplitude and time of occurrence of the critical event are determined. An uncertainty zone is derived at the extremes of the protected section having a length dependent on the precision of a time standard to which the monitoring stations are referenced and on the exactness of fluid velocity in the pipeline. An operator is so informed if the location of the critical event is determined to fall in the uncertainty zone. It is also possible to determine whether wave fronts correspond to an event occurring outside the protected section. Information from the resulting pass-through wave is used to update needed parameters useful for the critical event determinations.

Abstract: Direction of travel from a wave front in a pipeline is determined with two pressure sensors spaced relatively near to each other so that the site from which the wave front emanated is not located therebetween. For each sensor, a determination is made as to whether a detected signal has exceeded a negative or a positive threshold. In addition, the sensor outputs are subtracted from each other to determine which sensor detected the wave front first. Combining the resulting signals yields information on the nature of the wave front and its direction of travel.

Abstract: A low power valve actuator includes a small motor that rotates an Acme drive screw. The rotary motion of the drive screw is translated into linear motion of a drive nut-traveling block, which is guided along and held against rotation by a pair of spaced parallel guide rods. A cantilever pin carried on the traveling block engages in a groove extending longitudinally of, a Scotch yoke lever, which translates the linear motion back into rotary motion at a further mechanical advantage. The Scotch yoke lever is reinforced and strengthened by reason of the fact that the groove is not a through-slot, but extends only partially through the lever arm. The device is made more compact by reason of the fact that the groove in the Scotch yoke lever can actually extend over the top of the valve stem.