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Analysis and Solutions to the Dripping of Fluid at the Outlet of Peristaltic Pump

time:2017-11-06 14:33:00from:JIHPUMP read:

        The production of dripping phenomenon at the outlet of peristaltic pumps: When using peristaltic pumps, we usually hope that the liquid in the pipeline will stop flowing immediately when the pump stops. However, it often happens that we find that the liquid in the pipeline slowly drips until all the liquid in the hanging pipe has dripped and stopped flowing. This is a big problem for us when using peristaltic pumps as quantitative tools. So, what causes this dripping phenomenon? The engineers from JieHeng Peristaltic Pumps will tell you that this is a normal liquid flow phenomenon. The main reason is that the liquid is filled in the hanging outlet pipeline during operation. However, when the pump stops, due to its own gravity and viscosity, the liquid in the outlet edge of the pipeline will naturally drip down until all the liquid in the hanging pipeline has dripped and stopped.

        In addition to the above-mentioned gravity-induced dripping, can peristaltic pumps produce siphoning? The answer is no. The working principle of peristaltic pumps determines that the rotor of the pump needs to fully press against the pump tube to create negative pressure at the inlet and positive pressure at the outlet. Therefore, when the peristaltic pump stops operating, the inlet and outlet are completely closed. Even though the outlet pipeline hangs down, there will be no siphoning effect on the entire peristaltic pump hose.

        After understanding the reason for the dripping of liquid in the outlet pipeline of peristaltic pumps, how can we solve it? The analysis and solution from JieHeng Peristaltic Pumps are as follows: Due to its own gravity, fluid will fall in the pipeline. However, since the liquid fills the pipeline and only one end is connected to the atmosphere while the other end is blocked by the rotor of the peristaltic pump, a tension will be generated in the pipeline. However, since this tension cannot overcome the gravity of the liquid, it will still drip. Since we know that the tension in the pipeline is too small, is there a way to increase it and overcome gravity? Of course, we can easily increase the tension in the liquid in the pipeline by reducing the diameter of the pipeline outlet. In addition to this simple method, we can also add a one-way pressure valve at the outlet to solve the dripping phenomenon. When the pump is working, the pressure generated by the pump itself opens the one-way valve. When the pump stops, the pressure disappears and the one-way valve automatically closes.

        Some practical issues to note: Due to pulse phenomena during peristaltic pump operation, i.e., sudden decreases in liquid flow caused by pulses resulting in backflow and suction, the length of the small-diameter outlet set up must exceed the length of peristaltic pump backflow. If the small-diameter outlet is too short, due to backflow, the liquid surface in the outlet does not stay on the small-diameter pipeline, and a larger tension is not formed, so it naturally fails to prevent dripping.

        There are also limitations to using liquid's own tension to prevent dripping. Since liquid will evaporate over time, if you need a longer time for liquid anti-dripping, then with evaporation, anti-dripping may fail. Therefore, if your system often requires a long period of downtime after use, then a completely closed one-way valve system is still the only solution.

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