Pressure and temperature selection
The actual working pressure of the fluid in the pipeline should be less than the rated working pressure of the flowmeter. Pay attention to whether there is negative pressure in the pipeline, such as the evaporation process, and the negative pressure is up to -60KPa. Such working conditions should be communicated with the manufacturer's technicians when ordering. Strict requirements are imposed on the lining material. The actual temperature should meet the temperature requirements specified by the flowmeter.
Power supply selection
The choice of the electromagnetic flowmeter power supply should be selected according to the flowmeter itself and the environment of the site. If the site allows, the power supply is convenient, safe and easy to maintain. As a chemical company, more than 90% of the raw materials and process links are in the liquid phase. During operation, the internal humidity of the workshop is large, and no flammable gas is generated during the whole operation. It is safer to use DC24V for power supply. Outdoor dry environment, choose AC220V power supply, convenient lead wire, good maintenance and low cost.
Some explosion-proof occasions, such as flowmeters used in gas boilers, are ideal for battery-powered electromagnetic flowmeters.
The ultrasonic flowmeter is designed based on the geometrical principle that the velocity of the ultrasonic wave propagating in the flowing medium is equal to the average flow velocity of the measured medium and the velocity of the acoustic wave itself. It is also measured by the flow rate to reflect the flow rate. Although the ultrasonic flowmeter appeared only in the 1970s, it is very popular because it can be made into a non-contact type and can be connected to the ultrasonic water level gauge for opening flow measurement without disturbing or resisting the fluid. There are promising flow meters.
Ultrasonic Doppler flowmeters fabricated using the Doppler effect have received widespread attention in recent years and are considered to be ideal gauges for non-contact measurement of two-phase flow.
Fluid oscillating flowmeter
The fluid oscillating flowmeter is designed based on the principle that the fluid will oscillate when flowing under specific flow conditions, and the frequency of the oscillation is proportional to the flow velocity. When the flow cross section is constant, the flow rate is proportional to the flow volume of the pilot volume. Therefore, the flow rate can be measured by measuring the oscillation frequency. This flowmeter was developed and developed in the 1970s. Because it combines the advantages of non-rotating components and pulsed digital output, it has a promising future. At present, typical products include vortex flowmeters and spiral vortex flowmeters.
Turbine Flowmeter Product Introduction
A flow meter that uses a turbine for measurement. It first converts the flow rate to the speed of the turbine and then converts the speed into an electrical signal proportional to the flow. This flow meter is used to detect instantaneous flow and total integrated flow, and its output signal is frequency, which is easy to digitize. In the figure, the induction coil and the permanent magnet are fixed together on the casing. When the ferromagnetic turbine blade passes the magnet, the magnetic resistance of the magnetic circuit changes to generate an induced signal. The signal is amplified and shaped by an amplifier and sent to a counter or frequency meter to display the total integrated flow. At the same time, the pulse frequency is frequency-voltage converted to indicate the instantaneous flow rate. The speed of the impeller is proportional to the flow rate, and the number of revolutions of the impeller is proportional to the total amount flowing. The output of the turbine flow meter is a frequency modulated signal that not only improves the immunity of the detection circuit, but also simplifies the flow detection system. It has a turndown ratio of 10:1 and an accuracy of ±0.2%. Turbine flowmeters with small inertia and small size have a time constant of 0.01 seconds.
Turbine flowmeter is the main type of velocity flowmeter. When the fluid to be measured flows through the turbine flowmeter sensor, under the action of the fluid, the impeller is forced to rotate, and its rotational speed is proportional to the average flow velocity of the pipeline. At the same time, the blade periodicity The magnetic flux generated by the electromagnet is cut and the magnetic flux of the coil is changed. According to the principle of electromagnetic induction, a pulsating potential signal, that is, an electric pulse signal, is generated in the coil, and the frequency of the electric pulsation signal is proportional to the flow rate of the fluid to be measured.