GB975712A - Improvements in mass flowmeters - Google Patents

Abstract

975,712. Measuring fluid flow. FLO-TRON Inc. Sept. 22, 1962, No. 36119/62. Heading G1R. A meter for measuring the mass flow rate of a fluid comprises a conduit with means for measuring pressures at localities spaced along the length of the conduit and means for subtracting a portion of the main flow from one of these localities and adding it at another. The pressures are measured by a suitable meter 9 connected to a pressure-head differential transducer 8. The subsiduary flow q is propelled by pumps 6 and 7 and may be greater or less in volume than the main flow Q; preferably it is greater to enable small values of Q to be measured very accurately. Alternative arrangements (Figs. 1, 2 and 5 not shown) either omit the orifices 10 and 11, or provide for taking pairs of pressures, one on each side of each orifice with separate transducer and meter for each pair Fig. 6 illustrates an arrangement in which the main flow Q is divided into two equal flows Q-I and I in separate conduits 2 and 3. Each conduit has a pair of orifices 18 and 19; 20 and 21 between which a pump 14 operates to transfer fluid from one conduit to the other whilst the resulting pressures P 2 and P 3 are measured at the points of joinder of the transverse conduit 15. By suitably combining the pressure differences sensed by the transducers according to the system employed the mass flow velocity can be directly derived. Figs. 9 and 11 show a flowmeter based on the arrangement in Fig. 4 where a constant speed motor rotates pump rotors 30 and 32, in a housing 26 where a main inlet 28 and a main outlet 35 open into chambers 29 and 43 respectively. The fluid can flow between the chambers 29 and 43 either through the rotors 30 and 32 or through orifices 33 and 34 (Fig. 11) whilst ducts 39 and 40 connect with a transducer and pressure gauge.