Liquid flow meter as the main measuring instrument in the sewage treatment plant, is the basis of the settlement between the two sides. Due to other types of liquid flowmeter (such as turbine flowmeter, vortex flowmeter, etc.) on the water quality requirements are relatively high, the liquid flowmeter commonly used in wastewater treatment plants are electromagnetic flowmeter and ultrasonic flowmeter.
Electromagnetic flowmeter is mainly used to measure the volume flow of a variety of conductive liquids, can not measure non-conductive fluids (oil), containing larger bubbles of liquid and steam. According to the structure of the electromagnetic flowmeter is mainly divided into a body type and split type. Split electromagnetic flowmeter used in vibration, containing explosive gases and high temperature fluid occasions; and in general, a body electromagnetic flowmeter can meet the requirements.
Ultrasonic flowmeter is a meter for measuring volume flow without obstruction. It is suitable for industrial production of almost all liquids, including slurry, high accuracy. Particularly suitable for the solution of flow measurement difficulties, especially for large mouth diameter flow measurement field. Ultrasonic flowmeter requires relatively clean fluid. Pipeline fouling will affect the accuracy. Ultrasonic flowmeter is more and more widely used in industrial production, because it can effectively measure the flow of natural gas. This measurement is non-insertion and does not cause pressure loss.
The two types of flow meters have their own advantages and disadvantages:
(1) The advantages of electromagnetic flowmeter in sewage measurement are mainly as follows:
(a) small pressure loss is relatively small. Electromagnetic flowmeter sensor structure is simple, there is no movable parts in the measuring tube, there is no obstacle to the flow of fluid throttling parts, when the fluid through the flowmeter will not cause any additional pressure loss, the flowmeter resistance is only the same length of the pipeline along the resistance is the flowmeter in the flowmeter in the operation of the lowest energy consumption in one of the flow meter.
(b) can measure the flow of dirty media and suspended liquid-solid two-phase flow. Electromagnetic flowmeter measurement channel is a smooth straight pipe without flow detection parts, not easy to block the liquid-solid two-phase fluid containing solid particles or fibers.
(c) electromagnetic flowmeter measured volume flow, practically independent of fluid density, viscosity, temperature, pressure and conductivity changes. Disadvantages mainly can not measure the liquid containing a large number of gases.
(2) ultrasonic flowmeter in the measurement of sewage has the following advantages:
(a) can do non-contact measurement.
(b) and electromagnetic flow meter is generally no flow resistance measurement, no pressure loss.
(c) can measure non-conductive liquids, no obstruction measurement of electromagnetic flowmeter is a complement.
Time method ultrasonic flowmeter can only be used for clean liquids, generally in the sewage plant is mainly used for the flow measurement of the outlet pipe.
Taking into account the sewage measurement process in the pipeline impurities, bubbles on the electromagnetic flowmeter, as well as ultrasonic flowmeter in the routine maintenance and maintenance of the importance of a flowmeter dedicated to the measurement of sewage will be the flow of workers in the future efforts to study the direction.