Measuring and testing – Volume or rate of flow – Tank type
Patent
1995-04-24
1997-06-03
Dombroske, George M.
Measuring and testing
Volume or rate of flow
Tank type
73215, 119 1417, G01F 176
Patent
active
056356374
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
This invention relates to the measurement of fluid flow rate and/or total mass flow. The invention relates particularly, though not solely to measuring the flow rate and/or total mass flow of milk supplied during milking of cows. In this application the invention provides an electronic milk meter.
By "flow rate" it is meant liquid rate in mass unit time e.g. kg/min. By "total mass flow" it is meant the integration of flow over the measurement time.
When measuring the flow of, in particular, liquids which are not uniform in composition, such as, for example, the milk, delivered during machine milking which foams due to substantial and varying amounts of entrained air and other gases, an accurate determination of the flow rate or the total mass flow of liquid is difficult to achieve. With milk, because of the differing quantities of air and other gases contained within the milk, the density of the milk may change substantially during the milking process. An acceptable accuracy for total mass flow is within 2% of the actual yield of milk supplied. It has been found that it is difficult if not impossible to remove the gas from milk to an extent that will enable this accuracy to be achieved whilst measuring the milk volume during milking or very soon after the milking occurs. As one of the main purposes of measuring the total mass flow is to determine the milk yield from each animal substantial removal of gas would require the milk to be retained in individual cow portions for a substantial period of time. Clearly, this is impractical. A method proposed to overcome the problem of density variation in measuring milk volume is described in U.S. Pat. No. 5,035,139 where the foam profile of milk passing through a chamber is measured by measuring specific densities of the milk at different heights in the chamber. It would, however, be advantageous to measure total mass flow in a more direct manner rather than by making numerous volume and density measurements.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a means of measuring flow rate and/or total mass flow which will simplify the aforementioned measuring procedure or which will at least provide the industry with a useful choice.
Accordingly in one aspect, the invention consists in an apparatus for measuring flow rate of a fluid comprising, a chamber, an inlet to the chamber, an outlet from the chamber, means for determining the mass of fluid in the chamber wherein the shape of the chamber and/or the shape of at least part of the fluid flow path through the chamber is such that the flow rate of a selected fluid through the chamber is in a substantially linear relationship to the mass measured by the means.
In a further aspect, the invention consists in an apparatus for measuring total mass flow of a fluid comprising an apparatus for measuring flow rate according to the preceding paragraph and summation means to determine total mass flow by integrating a plurality of measurements of said flow rate with respect to time.
In a still further aspect, the invention consists in a method of measuring flow rate of a fluid comprising the steps of weighing a chamber through which fluid flows, the chamber being shaped and/or at least part of the fluid flow path through the chamber being shaped such that the flow rate of a selected fluid is in a substantially linear relationship to the weight of fluid within the chamber.
In a still further aspect, the invention consists in a method of measuring total mass flow of a fluid comprising measuring flow rate according to the method of the preceding paragraph and integrating a plurality of measurements of the flow rate with respect to time to determine a total mass flow of fluid passed through the chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred forms of the invention will now be described with reference to the accompanying drawings in which:
FIG. 1 is a plan view of the mechanical components of a first form of the apparatus for measuring flow rate and/or to
REFERENCES:
patent: 4452176 (1984-06-01), Hoefelmayr et al.
patent: 4955270 (1990-09-01), Volk
patent: 5035139 (1991-07-01), Hoefelmayr et al.
Boult Brian F.
Dingley Geoffrey W.
Heslin Michael B.
Jackson Peter S.
Ryan Kevin
Dombroske George M.
Patel Harshad
Tru-Test Limited
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