The accuracy of the peristaltic pump
is 0.5%-1%. Usually, users will have 2 common problems:
1. Now that the accuracy of the peristaltic pump
can reach this level, why sometimes we can achieve this accuracy when we use a pump to dispense more than 2ml, but it can't be satisfied when it is less than 2ml?
2. When the pump head rotates at a low speed, why does the naked eye see the liquid flow in the pump tube stop?
The answer is as follows:
1. The peristaltic pump relies on the runner to squeeze the hose to achieve a constant flow output, that is, a fixed flow output will be produced every revolution. However, each time the peristaltic pump runner leaves the pump tube during its rotation, the liquid will be sucked back due to the rebound of the pump tube, resulting in a sudden decrease in the discharge flow, that is, a pulse. Usually, a peristaltic pump has several squeezing wheels, and you will see several pulses at the discharge port. If our pump has 2 pressure wheels, each revolution will produce a 3ml flow, if you want to dispense 1ml. This means that the pump only needs to run about 1/3 of a circle, and the peristaltic pump cannot guarantee the reproducibility of the flow within one circle due to the existence of the impulse of the runner. As long as the flow of the peristaltic pump is greater than the volume of liquid produced per revolution when the peristaltic pump is dispense stopped, it will always stop at the point when it was started last time.
Conclusion: The distribution flow rate of the peristaltic pump is selected to exceed the flow rate per revolution of the peristaltic pump.
2. When the speed of the pump head is low, the liquid at the inlet of the pump is seen to stop. This is because when the runner just presses on the pump tube, because the inner space of the pump tube becomes smaller, the liquid is in the state of draining back At this time, the forward flow of the liquid is offset by the back-discharge. But this does not affect the normal discharge of the liquid, so the peristaltic pump accuracy
of the discharge is still constant.