| 摘要 |
Methods and apparatus for measuring the volume and/or flow rate of liquid contained in a vessel of the type from which liquid is dispensed via a fluid path having one end submerged in the liquid and another end extending above the level of said liquid by a pressure difference DP between a pressure P2 above the liquid and a pressure P1 at a predetermined point in said fluid path. The volume of liquid is deduced from DP and the height H between the surface of said liquid and said predetermined point in said fluid path, by determining the depth D of said liquid from said height H, and determining the volume of said liquid from said depth D. The flow rate is deduced from a first value DP1 of DP under zero flow conditions and a second value DP2 when liquid is flowing through said fluid path and determining the flow rate Q of said liquid from the difference between DP2 and DP1. Flow rates may be time integrated in order to determine volumes dispensed from the vessel. The invention provides the basis for a variety of stock monitoring and yield analysis systems, devices and functions; e.g. in relation to beer kegs. Tapping heads for beer kegs or the like may incorporate pressure sensing ports and/or sensors/gauges for use in accordance with the invention.
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