Positive displacement vapor control apparatus for fluid transfer

Claim 1

In combination with a closed system including pump means for forcibly transferring a vaporizable liquid from a liquid supply tank at a variable flow rate via a liquid conduit to a liquid receiving chamber in which vapor of said liquid has accumulated, which system includes a vapor conduit communicating with said accumulated vapor and providing passage thereof out of contact with liquid in said liquid transfer conduit from said chamber to said supply tank; positive displacement fluid metering means connected in series relation with said vapor conduit and drivable at variable drive speed for displacing vapor effectively positively along said vapor conduit toward said supply tank at a rate proportional to said drive speed and substantially independent of the relative pressures normally existing in the receiving chamber and the supply tank, and positive displacement rotary means connected in series with said liquid conduit for deriving rotary movement proportional to the rate of liquid flow therein and for driving said metering means at a drive speed proportional to said rotary movement, whereby said volume of vapor displaced toward said supply tank maintains a predetermined proportion to the volume of liquid flowing to said receiving chamber, substantially independently of the rate of said liquid flow.