Peristaltic pump filling nozzles dripping problem 2 (viscous fluid)

During the filling process of the peristaltic pump, sometimes there will be dripping problems at the filling port, which is not allowed in the production process and needs to be adjusted according to different filling conditions. For viscous fluids, in addition to paying attention to some situations that should be paid attention to for non-viscous fluids, there are some special phenomena that require further adjustments.

Phenomenon 1:

After the peristaltic pump filling is stopped, a small amount of fluid will continue to flow out of the filling port.

Cause analysis: In this case, it is generally caused by the peristaltic pump head The hose is too long or the filling needle is too small relative to the flow rate of the viscous fluid. During the transmission process of viscous fluid, the friction resistance with the hose wall is relatively large, so the peristaltic pump needs to provide a higher operating pressure to ensure the normal transmission speed of the viscous fluid. This pressure will be distributed in various parts of the hose at the head, and the hose will expand. When the peristaltic pump stops, the hose at the head will return to the state before the expansion, which will cause a small amount of viscous fluid to flow out of the filling port after the shutdown, affecting the filling accuracy; in addition, if the filling port is too thin, it will also cause the pressure inside the hose at the head to increase, resulting in the continuous outflow of viscous fluid after the filling is completed.

Solution: ① If the flow rate allows, try to use a hose with a smaller ratio of hose inner diameter to wall thickness. Such a hose has better pressure resistance, that is, when there is pressure inside the hose, the elastic deformation of the hose will be very small, which can greatly reduce or avoid the phenomenon of a small amount of continuous dripping of viscous liquid at the filling port. In addition, the smaller the inner diameter of the hose, the better. A hose that is too thin may not be able to transmit viscous liquids. ②When the surface tension of the liquid allows, try to increase the inner diameter of the filling needle as much as possible, which can significantly reduce the pressure inside the hose and effectively reduce or avoid the phenomenon of a small amount of continuous dripping of viscous liquid at the filling port. ③After filling, use the driver's back suction function (the quasi-dispensing peristaltic pump has this function), so that after the filling is completed, the pressure inside the hose can be quickly released through the back suction of the pump head, which can avoid the phenomenon of a small amount of continuous dripping of viscous liquid at the filling port. According to the viscosity of the liquid and the pipeline conditions, the back suction angle needs to be adjusted appropriately.

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Phenomenon 2:

After the peristaltic pump stops filling, there will be viscous liquid hanging on the filling needle at the filling port.

Cause analysis: In this case, it is mainly because the viscosity of the viscous liquid is high, and the flow rate of the liquid at the filling port is not enough to overcome the adhesion between the liquid and the needle port, resulting in the liquid hanging on the filling needle.

Solution: ① During the filling process, move the filling needle up and down so that the filling needle can contact the liquid being filled. When the filling is completed, lift the filling needle. This can effectively solve the problem of liquid hanging on the needle. ② After the filling is completed, use the driver's back suction function (the quasi-dispensing peristaltic pump has this function). After the filling is completed, the viscous liquid hanging on the needle can be quickly cut off through the back suction of the pump head, which can also effectively solve the problem of liquid hanging on the needle.