How to Improve the Filling Accuracy of Peristaltic Pump?

The so-called filling is the process of transferring a certain amount of liquid within a specified time. Filling accuracy error refers to measuring the filling volume of each filling after multiple fillings. The formula is: filling accuracy = (maximum value-minimum value)/average value. Therefore, to ensure the consistency of each filling volume is to improve the filling accuracy. The technologies currently used in the peristaltic pump filling market are not the same. Now RUNZE FLUID will mainly talk about the characteristics of various technologies.

1. Use a timer to control the filling volume of the peristaltic pump

This method is the easiest to implement, but the error is also large. The main reasons are the influence of temperature and the influence of program structure. The single-chip microcomputer works by the frequency output of the crystal oscillator, and the temperature has an influence on the frequency of the crystal oscillator. A good crystal oscillator can minimize the impact, but it cannot be eliminated. This impact directly determines the size of the timer time base in the single-chip microcomputer, thereby affecting the set time length, and causing the inconsistency of the working time of the peristaltic transfer pump each time, thus causing errors. In addition, it is not advisable to use the program to accurately generate the time value. When working, the influence of various interrupt operations will cause the time error, and this error is unpredictable and cannot be compensated.

2. Use the number of pulses to control the filling volume of the peristaltic pump

This method can ensure that the total number of operating angles of the peristaltic pump for each distribution is the same, and the filling accuracy is much improved relative to the time control method. However, due to the pulsation phenomenon of the peristaltic pump when transferring liquid, although the total operating angle can be controlled by the number of pulses, the instantaneous flow rate is at the peak or trough of the pulsation or the state of the flow rate in the middle is uncertain, that is, the position when the roller stops. The position is inconsistent after one allocation. This will cause distribution errors due to the different stopping positions of the rollers each time. This kind of distribution error is relatively small compared to the larger amount of liquid distribution, mainly because it will have a great influence on the distribution of a smaller amount of liquid.

3. Use angle control technology to control the filling volume of the peristaltic pump

This method uses the number of pulses to control the filling volume based on the addition of angle control technology during shutdown to ensure that the rollers of the peristaltic pump are in the same position every time it is shut down, thus eliminating the influence of the peristaltic pump pulsation phenomenon on the filling volume, which is a very obvious improvement to the filling of small flow.

The above three filling technologies are all open-loop control, and the flow attenuation factor of the peristaltic hose pump is not considered. In actual work, it should be calibrated regularly to achieve higher filling accuracy.