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Which flow meter should be used for corrosive gas

Which flow meter should be used for corrosive gases? Ultrasonic flowmeter. In recent years, the domestic and international natural gas industry has achieved rapid development, which has greatly promoted the development of natural gas meters. The multi-channel ultrasonic flowmeter developed specifically for natural gas metering is a dazzling pearl. For corrosive gas flow measurement, it should be feasible, as long as the inner wall of the measuring tube is treated for corrosion protection. However, specific application examples have not been reported yet. In addition, there is a situation that is not optimistic, that is, the price of such a flow meter is too high, and it is necessary for the manufacturer to reduce the cost and lower the selling price.
Ultrasonic flowmeters equipped with clip-on transducers developed in recent years, if the pipeline itself is resistant to corrosion, it is not necessary to consider the corrosion resistance of the instrument. For example, the pipe uses a corrosion-resistant lining, but if there is an air gap between the lining and the metal pipe, it will also cause trouble for the clip-on ultrasonic flowmeter.
For metal pipes without corrosion-resistant lining, the inner wall is often corroded after prolonged corrosion, which often causes the "V"-shaped and "W"-shaped transducers to have inconsistent sound reflection, so the signal strength becomes weak. It is not even possible to measure normally. These should be noted when using an ultrasonic flowmeter.

b. Throttle differential pressure flowmeter. Stereotype commercial electromagnetic flowmeters for corrosive media have not yet been reported, but such gauges developed by users have been reported decades ago, with very successful chlorine flow measurements.
The technology of process equipment for dealing with corrosive gases has matured for decades. For example, various diameter pipes are lined with rubber, lining glass, and PTFE. The instrument professional borrows this advantage, and the micro-crystal glass orifice plate with excellent corrosion resistance performance is professionally clamped on the process pipeline by the process professional, and then a nozzle is reserved by the process professional before and after the orifice plate. The blue differential pressure transmitter is mounted on the nozzle. The isolation diaphragm of the transmitter was originally made of molybdenum-containing stainless steel. In order to solve the corrosion problem, a layer of polytetrafluoroethylene separator was placed on the diaphragm.

Such anti-corrosion methods are sometimes not ideal. After using the stainless steel diaphragm of the differential pressure transmitter for a period of time, pinhole corrosion is still found, that is, several holes with extremely small diameter appear on the stainless steel diaphragm, which has been confirmed by research. The ions in the fluid penetrate the Teflon diaphragm and come into contact with the stainless steel diaphragm to corrode it. The instrument manufacturer has further improved the diaphragm material, for example, providing a double-flange differential pressure transmitter with a diaphragm. However, as mentioned before, the diaphragm does not solve all the problems, but only makes the problem to be solved more.

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