Abstract: A compact system is provided for diverting excess flow of liquid such as waste water from a conduit and to retain debris within the conduit. This incorporates a control section (22), which may be generally cylindrical, and arranged to be rotatable about a longitudinal axis (23), and defining a discharge port (24) through which excess water can leave the conduit. In operation, the depth of water in the conduit would be measured (15) downstream of the control section (22), and the rotation of the control section (22) adjusted in accordance with whether the water surface is above or below a depth limit. The discharge port (24) may include a grille to retain any debris, and the apparatus may include brushes (27), scrapers (29) or water jets (26) to dislodge any material held on the grille when the discharge port is at a top centre position.

Abstract: Apparatus is described for accurately determining the elevation, E, of a pulse-echo ultrasonic range sensor (2) relative to a datum level (14). The figure shows vertical elevations of the apparatus with plate deployed at level-1 (12) and level-2 (13) above a datum level (14), the levels being separated by a known distance, D. The elevation of the sensor is given by the relationship: R1=D|(dt1/(dt2?dt1))| where dt1 and dt2 are the intervals of time, determined by the sensor, taken by a pulse-echo to transit the distances R1 and R2 respectively. This apparatus may also be used to determine sonic velocity, Sv from: Sv=|2D/(dt2?dt1)|.

Abstract: Apparatus is described for accurately determining the elevation, E, of a pulse-echo ultrasonic range sensor (2) relative to a datum level (14). The figure shows vertical elevations of the apparatus with plate deployed at level-1 (12) and level-2 (13) above a datum level (14), the levels being separated by a known distance, D. The elevation of the sensor is given by the relationship: R1=D|(dt1/(dt2?dt1))| where dt1 and dt2 are the intervals of time, determined by the sensor, taken by a pulse-echo to transit the distances R1 and R2 respectively.