The selection and determination of the diameter of the diaphragm pump is mainly based on the flow capacity of the valve, which is Cv. In the instrument design and selection of various projects, the Cv calculation of the Air diaphragm pump must be carried out, and the diaphragm pump design specification shall be provided. From the Cv calculation of the diaphragm pump to the determination of the valve diameter, the following steps are generally required: 1) Determine the calculation flow. The existing production capacity, equipment load and media conditions determine the Qmax and Qmin of the calculated flow. 2) Determine the pressure difference before and after the valve. Select S (resistance coefficient) according to the selected valve flow characteristics and system characteristics, and then determine and calculate the pressure difference. 3) Calculate Cv. Select the appropriate calculation formula and chart according to the adjusted medium to obtain Cmax and Cmin. 4) Choose Cv. According to Cmax, select the first level C> Cmax and close to it in the selected product standard series. 5) Checking calculation of diaphragm pump opening. Generally, it is required that the opening degree when calculating the flow rate is ≯90%, and the opening degree when calculating the flow rate is smaller than 10%. 6) Checking calculation of actual adjustable ratio of diaphragm pump. Generally, the actual adjustable ratio is required to be ≮10. 7) Determination of valve seat diameter and nominal diameter. After verification is appropriate, determine according to C.
In summary, the selection of diaphragm pumps is a very meticulous work, which requires not only solid professional theoretical knowledge, but also rich practical experience. A good choice is not only conducive to the adjustment of the PID parameters of the control loop, so that the adjusted parameters can be better controlled, but also the service life of the diaphragm pump is greatly increased. The choice of diaphragm pump should be tailored to local conditions, not static. It should be continuously summarized and innovated in the course of practice. Especially with the application of mechatronics technology, computer and digital information technology, the structure and function of diaphragm pumps have become better and more comprehensive. It provides great convenience for choosing diaphragm pump.
