| 摘要 |
666,461. Water supplies. GARVENSWERKE MASCHINEN-PUMPEN- & WAAGENFABRIK. W GARVENS. Nov. 10, 1949. [Dec. 6, 1948] No. 28857/49. Class 68 (i). In a domestic water installation the driving motor of the delivery pump is switched on when a predetermined minimum pressure is reached at a given point in the system and is switched off when the output of the pump reaches a predetermined minimum as the pressure at the given point increases. The pressure drop at the given point from when the motor is switched off until it is switched on is approximately one metre of water head. The apparatus has a stand pipe 7 which projects above the highest supply point of the system and when the motor 1 is switched off this stand pipe has been filled. When a tap is opened the level in the stand pipe drops and when the pipe is empty the variation in pressure on the pressure switch 9 due to the loss of head in the stand pipe is sufficient to switch on the motor. To reduce the frequency of the switching operations the capacity of the stand pipe is increased by widening the cross-section of the pipe over the whole or part of its length or by forming at the upper end a vessel from which the admission or discharge of air is controlled by a ball float valve. A pressure container 8 with a ball float valve may replace the stand pipe the container being filled with water except for that space occupied by an air cushion. |
