GB920783A - Improvements in apparatus for adding predetermined quantities of fluid additive to flowing fluid - Google Patents

Abstract

920,783. Mixing liquids in proportions. GILBARCO Ltd. May 5, 1961 [May 5, 1960], No. 15975/60. Class 86. Apparatus for adding intermittently to fluid flowing in a conduit an amount of additive proportional to the amount of fluid which has flowed in the conduit comprises a meter in the conduit controlling a pneumatic switch which operates periodically the additive supplying means. In the conduit 1, a meter 3 rotates a shaft 5 carrying, in the housing 11, a worm 41 which drives a worm-wheel 43 having a cam 47 which actuates, once in each revolution, the cam follower 49 and lever 51. Each actuation of the lever 51 admits pressure air from the pipe 13 to the pipe 15 and thence to the control valve 17, whereby the air operated piston in the cylinder 19 moves from right to left. The piston in the additive pump cylinder 21 is coupled to that in the cylinder 19 and therefore moves also to discharge through the pipe 34 into the conduit 1. Upon the cam follower 49 leaving the cam the piston in the cylinder 19 is returned, recharging the cylinder 21. The stroke of the pistons and hence the quantity of additive may be adjusted by means of the adjustable stop 37. In modifications, additive may be injected on both forward and return strokes of the pistons, or the injection unit may be a single cylinder having a piston biased to one end thereof; compressed air being supplied to push the cylinder against the bias to discharge additive from the space on the other side. The meter may measure the flow in a by-pass being in known ratio to the flow in the main conduit, but preferably the additive is injected upstream of the meter which measures the total flow of fluid plus additive.