GB1232400A - - Google Patents

Abstract

1,232,400. Anti-siphon means for pumps. PORT OF LONDON AUTHORITY. March 13, 1969 [Dec.22, 1967], No.58405/67. Heading F1C. An anti-siphon valve mounted on the crown of a siphon discharge tube of a pump is mechanically biased to the open position and provided with means to open and close it, the means for closing it being arranged to come into operation only when the pump is operated, and there being means for providing a delay between the commencement of pump operation and the operation of the valve closing means. The anti-siphon valve 1 is biased towards the open position shown by a spring or a counterweight 2. When the electrically driven pump (not shown) is started, a solenoid valve 18 electrically connected with the pump opens to admit high-pressure air via time-delay means comprising a uni-directional port 17 and an air reservoir 16 to an air-operated valve 12 to open the latter. The valve 12 then admits high-pressure air from a line 14 to a line 13 to move a valve 8 against the action of a spring 9 into the position shown, in which it admits highpressure air from a line 10 into the left-hand side of a cylinder 5 to cause a piston 4 to close the antisiphon valve 1, and also vents the right-hand side of the cylinder to atmosphere. The time delay permits the discharge of air and formation of the siphon. In cessation of pump operation, the valve 8 reverts to its normal position and admits lowpressure air from a line 11 to the right-hand side of the cylinder 5 to open the anti-siphon valve 1 and also vents the left-hand side of the cylinder to atmosphere. In the event of failure of the electrical supply or the air supply, the system fails safe, with reversion of the anti-siphon valve 1 to its open position. To guard against mechanical failure, position-indicating switches may be mounted on the spindle of the anti-siphon valve 1 to transmit a warning to a control room. Instead of being pneumatically operated, the anti-siphon valve may be opened and closed by a pair of opposed solenoids, an electrical time-delay means being used to ensure delay of operation of the solenoid for effecting closure.