The phenomenon of dripping at the outlet of the peristaltic pump
: When we use the peristaltic pump, we usually hope that the liquid in the pipeline will stop flowing down as the pump stops. However, we often find that the pipeline is false. The liquid in the pipe will slowly drip down, and the flow will not stop until the liquid in the sagging pipe has finished dripping. This is a big problem when we use a peristaltic pump as a quantitative tool. How did this dripping phenomenon occur? The engineer of the peristaltic pump will tell you that this is a normal liquid flow phenomenon. The main reason is that the liquid is filled with the sagging outlet pipe when it is working, but when the pump stops, the pipe outlet is Due to its own gravity and the ductility of the liquid, the liquid will naturally drop along the edge of the outlet, and it will not stop until the liquid in the sagging pipe is completely dripped.
In addition to the above-mentioned liquid dripping under its own weight, will the peristaltic pump
produce a siphon phenomenon? the answer is negative. Because the work of the peristaltic pump
determines that the runner needs to fully compress the pump tube during the work of the peristaltic pump so that negative pressure can be generated at the inlet and positive pressure at the outlet. Therefore, when the peristaltic pump stops running, the inlet and outlet are completely shut off. Therefore, although the outlet pipeline sags, the entire peristaltic pump hose will not produce siphoning. After we know the cause of the liquid dripping in the outlet pipe of the peristaltic pump, how can we solve it?
The answer and analysis of the peristaltic pump are as follows: the fluid in the pipeline will fall due to its own gravity, but because the liquid is filled with the pipeline, and because the pipeline has only one end connected to the atmosphere, the other end is crushed by the peristaltic pump
runner and cannot communicate with the atmosphere. Connected, the liquid will produce tension in the pipeline, but because this tension cannot overcome the gravity of the liquid, the liquid will still drip. Now that we know that the tension of the liquid in the pipeline is too small, is there a way to expand the tension to overcome gravity? Of course, it is possible. We can easily increase the tension of the liquid in the pipeline by reducing the diameter of the pipe outlet, thereby solving the phenomenon of liquid dripping. Of course, in addition to this simple method, we can also add a one-way pressure valve to the outlet to solve the dripping phenomenon. When the pump is working, the pressure generated by the pump itself will open the one-way valve, and the pressure will disappear when the pump stops. The check valve closes automatically.
Problems that need to be paid attention to in actual work: Because the peristaltic pump has a pulse phenomenon during operation, that is to say, when the peristaltic pump liquid is transported, the liquid flow in the pipeline will suddenly decrease due to the pulse, and the phenomenon of back-suction and back-suction will be formed. The length of the small diameter of the pipeline outlet we set must exceed the length of the peristaltic pump. Because the set small diameter is too small, the outlet liquid level in the pipeline does not stay on the small-diameter pipeline due to the withdrawal of the liquid, and the large tension of the liquid is still not formed, and naturally, it will not be able to prevent dripping.
The liquid’s own tension and anti-drip also have their limitations, because the liquid itself will evaporate over time, so if you need the liquid for a long time, the anti-drip may fail as it evaporates, so if you The system will often have a longer shutdown after a period of use, so a completely closed one-way valve system is the best solution.