| 摘要 |
721,531. Gravity sand filters. TURN-OVER FILTER CO., Ltd. July 27, 1951. [Aug. 3, 1950] No. 19388/50. Class 46. [Also in Group XXIX] Filtering apparatus of the type in which the sand is washed by ejection from the bed through tubes by jets of water 'issuing from nozzles, the sand being carried up the tubes in a state of turmoil and then settling back on the bed incorporates at least one nozzle comprising pressure-actuable valve means in the nozzle adapted to be opened by the pressure of the wash water to allow issue of the jet, and to close automatically to prevent ingress of sand as soon as the pressure of the wash water falls below a predetermined amount, as for example when it is turned off. Wash water entering a nozzle casing 1 at 3, Fig. 1, depresses an annular flexible diaphragm 5 which in turn causes a hollow valve member 4 to which it is secured at the centre to move downwards to the position shown in this Figure. Wash water thus ejected. from the nozzle outlet 2 .passes up an openended tube 10, Fig. 3, mounted above the nozzle, and entrains sand from the filter bed to effect its circulation and hence cleaning. A number of nozzles, for example five, arranged on a circle may be simultaneously supplied with wash water by radial pipes 12 emanating from a central filtrate discharge pipe 13, the filtrate apertures 15 of which are temporarily obturated by a sleeve 16, which may be actuated by the mechanism 17 ... 20 or hydraulically, to permit either filtered or unfiltered water to be passed up the pipe 13 and sleeve 16. Where more than one nozzle is provided the spring-loading of each valve may be varied by an adjusting screw 7, Fig. 1, to ensure simultaneous operation of the nozzles and hence uniform distribution of wash water. A small balancing port 8 is provided in the wall 4 of the valve-member, Fig. 1, to connect both sides of the diaphragm 5 both to prevent opening of the valve by other than a steady and substantial pressure (of wash water) and to ensure that when the pressure is reduced by shutting off the flow of wash water a spring 6 is enabled to close the valve quickly and promptly. Operation of the nozzles may take place after or simultaneously with a backflushing operation (without sand circulation) brought about by manipulation of suitable valves. The nozzle casings 1 may alternatively be arranged horizontally or at any desired angle. |
