Patent GB-651661-A (GB)
Title: Improvements in means for measuring the heat supplied by a flow of liquid at variable temperature
IPC: G01K17/14
Filed: 1948-05-28
Abstract: 651,661. Measuring heat quantities. GAILLOUD, L. May 28, 1948, Nos. 14460 and 14461. Convention dates, June 3, 1947, and April 28, 1948. [Class 97 (iii)] Apparatus for measuring the quantity of heat supplied by a liquid flow of variable temperature comprises a valve 40, 57, sensitive to temperature variations, which directs a part of the flow into a conduit 37 leading to a volumetric meter 38, the remainder of the flow passing through a byepass 39, means being provided for balancing the pressures in the byepass and the conduit so that the quantity of liquid passing through the volumetric meter is directly proportional to the difference of temperature between the liquid and a prescribed minimum reference temperature. As shown, the temperature-sensitive portion of the valve comprises a bimetallic strip 40, the position of the free end of which varies with the temperature of the liquid and divides the flow into two separate streams. In a modification, the fixed end of the strip 40 may be mounted on a rod subject to the influence of a second bimetallic strip mounted in, e.g. the feed lines to a boiler so that the amount of heat recorded on the meter is compensation for variations in temperature of the feed liquid. In another embodiment the valve is constituted by a double piston having one head located in the conduit and the other in the byepass so as to vary the flow in each, the piston being controlled by the thermal expansions and contractions of a metal tube located in the supply line. As shown, the pressure - balancing means comprises two chambers, one, 43, connected to the conduit 37 and the other, 42, connected to the byepass 39, the two chambers being separated by a partition 45 whose displacements with unequal pressures in the conduit and byepass masks and unmasks, by means of a needle valve 48, an orifice 49 of a third chamber 44. The variations of the orifice 49 produce corresponding pressure variations in the third chamber 44 which actuate a member 56 attached to a diaphragm 51 located to regulate the flow in the byepass 39, 54 until the pressures are balanced. Hunting of the pressure balancing means may be controlled by means of a piston 55 attached to the needle valve 48. In a modification the movable diaphragms may be replaced by pistons. The flow resistance in the conduit and byepass may be equalized by a spring-controlled valve 59, 60, 61. In another embodiment the pressure-balancing means is constituted by a cylinder having a specific gravity equal to that of the liquid and displaceable in a connecting conduit between the conduit 37 and the byepass 39 so as to vary the flow in the byepaas. In a further embodiment the pressures in the byepass and conduit are balanced by means of a valve controlling the flow in the byepass and operated by means of a diaphragm placed between the conduit and the byepass. Instead of being connected to the conduit and the byepass the pressure-balancing arrangements may be operated from two pitot tubes whose heads are located in the two streams adjacent the free end of the bimetallic strip.