GB1397898A - Inflatable bladder liquid dispensers - Google Patents

Abstract

1397898 Delivering measured quantities of liquid CHEMECH ENG Ltd 26 June 1973 30440/73 Heading B8N A liquid dispenser comprises a measuring instrument, Fig. 1, and a pneumaticallyactuated dispensing head valve, Fig. 2, the spherical measuring vessel 10 of the measuring instrument containing an inflatable bladder 11 and being made by fixing two plastic mouldings together along a joint line which is in a plane containing the centreline of the vessel. The measuring instrument consists of liquid inlet and outlets 16, 22 adjacent non-return flap valves 17, 20, a compressed air connection 13 and pressure switches 28, 36. The liquid outlet 22 is connected to the inlet 43 of the dispensing head valve disposed above the measuring instrument. In operation, the liquid fills the vessel 10 and when a pressure of 3 lb./in.<SP>2</SP> is reached to operate the pressure switch 36, this closes electrical contacts to permit an electric current to flow to a solenoid-operated air valve in a control box 40 provided a manually-operated pushbutton adjacent the dispensing head valve has been operated to initiate a dispensing cycle. The compressed air is supplied to the inlet 44 on the dispensing head valve to lift the valve 45 and to the inlet 13 of the bladder 11 so that the liquid is pushed from the vessel 10 by the inflating bladder up to the dispensing head valve for delivery through an outlet 42. This air pressure is such that the liquid pressure at the top of the vessel 10 is more than 35 lb./in.<SP>2</SP> as the bladder is inflating. When the bladder is fully inflated, the liquid pressure at the top of the vessel above the non-return valve 20 drops to equal the static head of liquid due to the height of the dispensing valve head above the measuring instrument. This head is equivalent to less than 35 lb./in.<SP>2</SP>, the pressure at which the pressure switch 28 is set to operate. This drop in pressure then opens the electrical contacts to cause the solenoid operated air valve to shut off the supply of air to the dispensing head valve and the bladder and allow the dispensing head valve to close and the bladder 11 to deflate under the pressure of the new supply of liquid through the inlet 16. The pressure switch 36 again prevents operation of the push-button until the vessel has refilled and attained a pressure above 3 lb./in.<SP>2</SP>