The amount of fluid pumped by the
Metering Pump determines its metering capacity. The volumetric flow rate of the pump's output fluid is proportional to the stroke length L and the stroke frequency at a certain effective diaphragm area. F: VA*F*L. The pumping capacity determines the metering capacity. The volumetric flow rate of the pump's output fluid is proportional to the stroke length L and the stroke frequency F: V∝A*F*L under a certain effective diaphragm area.
The two-dimensional adjustment of the metering pump output can be achieved by adjusting the stroke length L and the stroke frequency F under the condition of the metering medium and the working pressure.
Although the stroke length and frequency can be used as the adjustment variables, in engineering applications, the stroke length is generally regarded as a coarse adjustment variable, and the stroke frequency is a fine adjustment variable: adjusting the stroke length to a certain value, and then adjusting the frequency to achieve fine adjustment and adjustment Flexibility. In relatively simple applications, the stroke length can also be set manually, using only the stroke frequency as a manipulated variable to simplify system configuration.
1, conventional analog / switching signal adjustment method
0/4-20mA analog current signal is widely used in process control applications as the standard for signal exchange between sensors, controllers and actuators. Metering pumps with external control function are mainly used to achieve external stroke frequency and stroke frequency. adjust.
Position servos are the most common method for adjusting stroke length. The integrated servo is designed to accept 0/4-20 mA control signals directly from the regulator or computer, automatically adjusting the stroke length from 0-100%. Internal change.
Relatively speaking, the method of adjusting the stroke frequency is mainly composed of two types: variable frequency motor control and direct relay contact control. The frequency converter controlled by the 0/4-20mA current signal drives the metering pump motor to run at the required speed. The adjustment of the stroke frequency is realized. For the electromagnetic drive and part of the motor-driven metering pump, the external contact signal can also be used to adjust the stroke frequency.
2, base control mode
In some special occasions, such as pH adjustment metering pumps as actuators, acid or alkali is added under the control of the regulator. In order to simplify system configuration and improve reliability, the microprocessor-based embedded control system is directly integrated into the metering. In the pump, only one external pH sensor can be used to form a complete regulation system. This base intelligent metering pump concept is also suitable for controlling other process parameters such as oxidation reduction potential (ORP) and residual chlorine concentration adjustment.
3, set programmatic control
Due to the integrated micro-processing computer, the regulation performance and operation performance of some metering pump products have been greatly improved. In addition to real-time metering flow adjustment following external control commands, there are quantitative addition, time series trigger program addition, event sequence triggering. Various modes of operation, such as programmatic addition, time-event hybrid triggering, and automatic calibration, can provide the total amount of fluid pumped, the number of remaining strokes and the volume of fluid to be delivered, the set stroke length, and other related metering pump operating parameters. And other useful information.
The time series triggers the program mode to make the metering pump completely add the working medium according to the set number of strokes or time according to the pre-planned task list according to the real-time clock. The time can be hourly, daily, working day, public holiday. The week and week are flexible for the cycle; and the event sequence triggers the program mode to make the metering pump completely according to the real-time trigger event according to the pre-planned task list, when the specific event occurs (contact input) according to the set stroke number Or time to quantitatively add working media.
The above two methods can be organically mixed to complete a more complex time-event hybrid trigger mode. Up to 81 events can be set.
A simple example is the cooling tower circulating water disinfection and algae-killing system. The disinfectant is added at a specific concentration according to the proportion of the supplementary water flow; and in the process of proportional addition according to the process requirements, the disinfectant should be added once a week in a large dose. Set at 12-13 on Friday) and ask to pause the proportional addition at this time. The entire programming is very simple and easy to implement complex and variable fluid addition tasks. http://NewsDetail319T2.html
Metering pump related products:
Plunger Metering Pump, diaphragm pump metering pump, corrosion-resistant metering pump China Hardware Business Network http://news.chinawj.com.cn Editor: (Hardware Business Network Information Center) http://news. Chinawj.com.cn
Zhejiang Ailipu Technology Co., Ltd.