GB729635A - Improvements in or relating to apparatus for dispensing measured quantities of liquid materials - Google Patents

Abstract

729,635. Delivering liquids in measured quantities. LINDARS, H. April 30, 1951 [May 1, 1950; July 21, 1950], Nos. 10694/50 and 18325/50. Class 106 (5). [Also in Groups XXVI, XXVIII and XXIX] A liquid measuring apparatus comprises several measuring chambers each having a free piston or an arcuately-oscillating vane, means operated by each piston or vane for controlling the displacement of another piston or vane, and means, such as an electrical counting device, for controlling the number of strokes of the pistons or vanes in order to deliver a predetermined quantity of liquid. In an embodiment operated by external power (air pressure), as shown in Fig. 1 (10694/50), two pistons 15a and 15b on a common piston rod 47 work in co-axial cylinders separated by a partition 48 and a change-over valve 24 controls the supply of compressed air from a pipe 49 to the outer side of one of the pistons so that it delivers a measured quantity of liquid past a ball valve 57 while the other piston is sucking in liquid from a main 1 past a ball-valve 51. A brush contact 36 on the piston rod 47 moves,over electrical contacts 33 connected to electrically-operated counting mechanism which controls either a stop valve in the main 1 or a switch in the counting circuit so as to stop the apparatus after the required number of strokes. In the embodiment shown in Fig. 1 (18325/50), the displacement of the pistons is effected by the liquid being measured and a separate pair, as illustrated, or a number of measuring chambers 1, 2 are provided, abutments 17, 18 on the piston rod for each cylinder actuating linkage 25 to control the change-over valve of the other cylinder, at the end of each stroke, so that the pistons are moved alternately and automatically control each other. The limit switches 21 and 22 are connected to the counting device, which controls a main valve 30 in the liquid supply line by means of a solenoid 30a. In a modification of this embodiment, the pipes from the ends of each cylinder are branched, one branch leading to a common delivery pipe and the other to the liquid supply; each branch has its own stop valve operated by a solenoid controlled by abutments on a piston rod engaging adjustably-mounted switches. A similar version to that of Fig. 1 (18325/50), but employing a pair of the double air-operated cylinders shown in Fig. 1 (10694/50) and having the change-over valves operated by motors controlled by switches operated by a striker on each piston rod, is also described. Mechanism may be associated with each piston rod for selecting desired fractions of a stroke. A modified cylinder with a jacket for heating or cooling fluid and external fluid-tight thimbles enclosing the adjustable stops or the piston rods is also described. The thimble enclosing the piston rod is filled with the same liquid as that being measured and is made of non-magnetic material so that a bar magnet may be fitted on the rod and operate totally-enclosed valveoperating switches fitted outside the thimble. Where the liquid being measured must be kept from contact with the atmosphere, the liquid system may be completely sealed, the piston rod and other glands being filled, at a pressure equal to that of the liquid, with a fluid to which it is inert. Specifications 638,614, [Group XXXVIII], and 691,907 and 729,633 are referred to.