How to choose the right flow meter
We all know that there are many types of flow meters.
Its purpose is to measure the flow of the medium, so how should we choose the use of the flow meter?
Flowmeters are mainly divided into: electromagnetic flowmeters, vortex flowmeters, mass flowmeters, orifice flowmeters, etc.
1. The measurement of mass flowmeter is relatively accurate and can be used in occasions with high accuracy requirements, so it is often used for foreign trade measurement of oil, and the accuracy can reach 0.05%; there is basically no requirement for the medium to be measured, and the viscosity of the medium exceeds 10000 The centipoise should pay attention to see if it will affect the measurement accuracy; for stability, the split type can be used to measure the medium of 350°;
2. The electromagnetic flowmeter can measure fluids with conductive medium such as process water, circulating water, acid-base solution, etc., but cannot measure gases, oils and organic solvents with extremely low conductivity. The accuracy is generally 0.4%-0.5%; the maximum temperature measured is 180°;
3. Vortex flowmeter can measure clean fluid medium and gas medium, but cannot measure mist fluid, layered fluid, bubble fluid and fluid with entrained solids, and the accuracy is generally 0.75% (liquid) and 1% (gas); temperature Up to 400°; stricter requirements for straight pipe sections;
4. The rotameter measures gas, liquid and crystalline and corrosive media, but cannot measure liquid and gas with suspended particles; the accuracy is 1.5%; it is used in low-precision situations, and for metal rotameters, it can measure high temperature and high pressure media;
5. Orifice plates are mainly used to measure gas, especially natural gas. Advanced orifice flowmeters are used in the measurement of natural gas export. Because of the low cost, they are mainly used in process detection, and there are requirements for straight pipe sections during installation. .
6. The throttling element (differential pressure transmitter) can measure liquid, gas, steam and other media, but cannot measure the fluid with particles and multi-phase density changes. It needs to be used in conjunction with the differential pressure transmitter.
For the water flow verification, there are conversion formulas, which can be easily understood by reading the book. For the selection of the flowmeter range, generally 20%-85% of the range can guarantee the accuracy.
