Recirculation system and method for automated dosing apparatus

In an automated dosing apparatus having a dosing head for dispensing a dose of flowable material, a supply canister for maintaining a supply of the flowable material under a pressure P.sub.1, a supply line which fluid-connects the supply canister to the dosing head, and a flow valve disposed in the supply line having at least closed and opened conditions which respectively prevent and allow the flowable material to flow to the dosing head, the improvement comprising a recirculation system which recirculates the flowable material during a recirculation mode to the supply canister, said recirculation system comprising:

• a buffer reservoir;
• a recirculation channel within the dosing head which is fluid-connected to the supply line;
• a recirculation line which fluid-connects the recirculation channel to the buffer reservoir:
• a transfer line which fluid-connects the buffer reservoir and the supply canister;
• a source of pressurizing fluid at a pressure P.sub.2 greater than the pressure P.sub.1 of the supply canister;
• a control valve operatively interconnecting the buffer reservoir to the source of pressurization fluid and having a vent condition wherein the buffer reservoir is vented and a pressurization condition wherein the buffer reservoir is fluid-connected to the source of pressurization fluid;
• and
• an automated controller operatively connected to the flow and control valves for (i) initiating a recirculation mode by issuing a first signal to cause the flow valve to assume its opened condition and thereby allow the flowable material to flow through the recirculation line to the buffer reservoir, whereby a volume of recirculated flowable material is accumulated within the buffer reservoir, and thereafter (ii) initiating a transfer mode by issuing a second signal to cause the control valve to assume its pressurization condition, the buffer reservoir being pressurized by the pressurization fluid in response to the control valve assuming the pressurization condition to thereby cause the volume of recirculated flowable material within the buffer reservoir to be transferred to the supply canister.