As a diaphragm metering pump, electromagnetically driven metering pump generates pulsating driving force with electromagnet, which saves the motor and transmission mechanism, makes the system small and compact and is an important branch of low pressure metering pump with small range. Now, precision metering pump technology has been very mature, the fluid metering capacity of up to 0-100,000 l / h, working pressure up to 4000bar, the scope of work covers all areas of industrial production requirements. Third, the metering pump control metering pump fluid pump out of each decision its measurement capacity. At a certain effective diaphragm area, the volumetric flow rate of the pump's output fluid is proportional to the stroke length L and the stroke frequency F: VαA * F * L By adjusting the stroke length L and the stroke frequency in the case of the measurement of the medium and the working pressure, F to achieve the two-dimensional adjustment of the metering pump output. Although both stroke length and frequency can be used as manipulated variables, the stroke length is generally considered as a coarse variable in engineering applications and the stroke frequency is a fine-tuned variable: the stroke length is adjusted to a certain value and fine-tuned by changing its frequency to increase Adjust flexibility. In relatively simple applications, the stroke length can also be set manually, using only the stroke frequency as a control variable, simplifying the system configuration. 3.1, conventional analog / switch signal conditioning methods Process control applications widely used 0 / 4-20mA analog current signal as a sensor, controller and actuator exchange of standards, metering pumps with external control function is also mainly used this way , To achieve the external adjustment of stroke frequency and stroke frequency. Position servos are the most common way to achieve stroke length adjustment. The integrated servos are designed to accept 0 / 4-20mA control signals directly from the regulator or computer, thus automatically adjusting the stroke length to vary from 0-100%. Relatively speaking, there are quite a few ways to realize the stroke frequency adjustment, mainly including inverter motor control and direct relay contact control. Driven by a 0 / 4-20mA current signal, the variable frequency drive operates the metering pump motor at the desired speed to adjust the stroke frequency. For solenoid driven and partially motor driven metering pumps, the external contact signal can also be used to adjust the stroke frequency. 3.2, base control mode In some special occasions, such as pH adjustment, metering pump as an actuator, add acid or alkali under the control of the regulator. To simplify system configuration and improve reliability, a microprocessor-based embedded control system is integrated directly into the dosing pump so that only a pH sensor is required to provide a complete conditioning system. The concept of a base smart metering pump is also suitable for controlling other process parameters such as ORP and residual chlorine concentration. 3.3, set the program-controlled As the internal integration of the microprocessor, some metering pump product performance and performance control has been fully enhanced, in addition to follow the external control commands to achieve real-time measurement of flow adjustment, but also with quantitative addition, time series Trigger program addition, event sequence trigger program addition, time-event hybrid trigger program addition and automatic calibration and other operating modes, and can be provided to pump the total amount of fluid, the number of remaining strokes and to be transported fluid capacity, set Stroke length and other relevant metering pump working parameters and other useful information. Time series triggers programmable working mode to make metering pump fully based on real-time clock, according to the pre-planned task list, according to the set time or time set by the designated quantitative processing medium, the time can be hourly, day, working day, Day, week and two weeks for the cycle of flexible set; and event sequence trigger program-based work so that the pump is based on real-time triggering event, according to pre-planned list of tasks, in the event of a specific incident (contact input) by setting The number of strokes or time to add the working medium.
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