| 摘要 |
PURPOSE:To obtain a flow rate measuring device which uses a differential pressure gauge eliminating the need for a Venturi tube, by detecting the difference in pressure between a measuring tube and a branch tube provided to the measuring tube. CONSTITUTION:Measuring tube 4 is provided with detection tube 4a and branch tube 4b which has air vent hole 9. Further, detection tube 4c is coupled with branch tube 4b at height (h) from measuring tube 4. The pressure at part 11 where detection tube 4a communicates is denoted as P2, and that at the part where detection tube 4c of height (h) from measuing tube 4 communicates is donated as P1. Then, since speed V1 at part 11 is equal to [2b(h+P2-P1)]<1/2>, P2-P1 detected by differential pressure detector 1 and height (h) of the difference in fitting position is added to P2-P1 by adding multiplier 8; and the sum is multiplied by 2g and the product is squared by switching arithmetic device 2 find velocity V1 of flow at part 11. In addition, V1 is multiplied by sectional area S of measuring tube 4 by arithmetic device 7 to find the quantity of flow at part 11. |
