The operating pressure of the melt pump has a significant impact on its sealing performance, and this impact is mainly manifested in the following aspects:
I. Impact of Excessive Pressure
When the operating pressure of the melt pump is excessively high, it may cause leakage of liquid from within the pump body through sealing devices such as labyrinth seals and packing layers. Specifically, high pressure can excessively compress or wear down sealing components, thereby reducing their sealing effectiveness. For melt pumps with packing seals, excessively high pressure can lead to leakage of the melt through the packing layers, resulting in not only waste of material but also potential contamination of the production environment.
II. Impact of Insufficient Pressure
Contrary to excessive pressure, insufficient operating pressure of the melt pump can also adversely affect sealing performance. In low-pressure conditions, sealing components may not be effectively compressed, allowing silicone oil used for lubricating and sealing the packing or external air to enter the liquid in the melt pump. This not only affects the purity and quality of the melt but may also disrupt subsequent production processes.
III. Importance of Pressure Regulation
To ensure the sealing performance of the melt pump, reasonable regulation of operating pressure is crucial. For instance, when the inlet of the pump body is under negative pressure, the pressure at the packing seal should be maintained higher than the external atmospheric pressure to prevent air from being sucked into the pump chamber. Additionally, when the outlet pressure of the pump body suddenly drops, the pressure of the pressure control valve should be promptly adjusted to prevent air from being drawn into the process system, which could lead to undesirable consequences such as fluctuations in pellet strands and wire breakage.
IV. Differences in Sealing Methods
There are various sealing methods for melt pumps, including spiral seals, packing seals, mechanical seals, and combined seals. These different sealing methods exhibit varying performance in response to changes in operating pressure. For example, mechanical seals offer advantages such as stable sealing conditions, low leakage rates, and long service life compared to packing seals, but they may require special maintenance and adjustment when subjected to extreme operating conditions.
V. Considerations in Practical Applications
In practical applications, the appropriate sealing method should be selected based on factors such as the specific model of the melt pump, material characteristics, and production process requirements. Regular inspections and maintenance of the sealing devices are also necessary. When adjusting the operating pressure, various factors should be comprehensively considered to ensure that the pump body operates in a stable and safe state.
In summary, the operating pressure of the melt pump has a crucial impact on its sealing performance. Reasonable pressure regulation and the selection of appropriate sealing methods are key to ensuring stable pump operation and guaranteeing product quality.
Previous：cap pe foam extruder melt pump and screen changer
Next：What are the application scenarios and selection references for melt pumps?
