GB1199002A - Improvements in or relating to Rotary Meters for Measuring the Mass Flow of a Stream of Fluid - Google Patents

Abstract

1,199,002. Rotary mass-flowmeters. R. MAURER (CONSULTANTS) Ltd. Aug. 21, 1967 [May 20, 1966], No.22703/66. Heading F1F. A rotary mass-flowmeter 210, Fig. 1, comprises a two-part cylindrical housing 211 having an enlarged diameter bore portion 212 and a fixed hollow concentric body 214 supported by axially directed inlet vanes 216 and outlet vanes 227. With the enlarged bore portion 212 is mounted a by-pass valve comprising a fixed inner sleeve 231 and an axially movable spring-loaded outer sleeve which according to the flow-rate through the meter divides the flow between an inner annular chamber 239 having fixed axial-flow vanes 232 and fixed inclined swirl producing guide vanes 217 and an outer annular by-pass chamber 241 having fixed flow straightener vanes 243. The two flows then combine in a mixing chamber 244 and pass through axially directed vanes 219 of a freely rotatable speed paddle having a pick-off 221 connected to a computer 245 to measure the swirl velocity of the fluid leaving the mixing chamber and axially directed vanes 223 of a torque paddle mounted on a shaft 224 which at its forward end carries a torque meter 229 having a power takeoff 230 connected to the computer 245 to feed into the computer the torsional reaction of the fluid leaving the mixing chamber. The quotient of the swirl velocity and the torsional reaction of the fluid gives the mass-flow through the meter. The by-pass valve which opens on increasing flow-rate to increase the flow through the by-pass reduces the torque range to acceptable limits for an extended flow range and maintains meter accuracy over a wider range of flow-rates. Trimmer vanes 246 are provided to compensate for any misalignment between the vanes of the two paddles and are set during calibration of the meter. The vanes of the two paddles need not be axially directed but must be of identical inclination. Modifications show and describe modified constructions of bypass valves. In one, the movable sleeve is controlled by the computer which through a motor and worm gearing moves the sleeve axially. In another, a coil spring when fully compressed seats on an abutment on the forward end of the enlarged bore portion 212. As flow increases the spring coils move apart to permit flow therethrough to the outer annular by-pass chamber.