Marine glass fiber reinforced plastic pipes are cooled by spraying in a vacuum tank

Both ends of the vacuum box are open, and flexible gaskets can be installed, and the extruded glass fiber reinforced plastic pipe is led out of the water tank through the gaskets at both ends. When the glass fiber reinforced plastic pipe starts to be pulled into production, the vacuum degree is quickly established, and the vacuum tank with the sizing element should be short. After the vacuum setting tank is set up, a so-called double-chamber vacuum tank is used next to the separate vacuum tank. The vacuum tank is divided into two parts: First, the vacuum chamber is equipped with a sizing sleeve, which facilitates the pulling operation of plastic pipe production. Moreover, when it is necessary to change the vacuum degree to adjust the friction force between the pipe and the sizing sleeve, it is quite flexible, and the vacuum degree requirements of different cooling stages can be fully considered.
For the additional straight-through gasket of the double-chamber vacuum tank, the subsequent vacuum chambers are separated from the sizing chamber, and the vacuum chambers are also isolated from each other. Each chamber has an adjustable exhaust valve, and its vacuum degree can be adjusted separately, and the vacuum degree should be adapted to the requirements of the cooling section. The vacuum chambers are adjustable, but they can share a single vacuum source, and several vacuum units can provide vacuum sources for the sizing chamber and subsequent cooling chamber. Vacuum box gaskets are mostly made of flexible rubber with a hole on it, the diameter of the hole is slightly smaller than the diameter of the extrusion tube to ensure the vacuum tightness of the end of the vacuum box and the different vacuum chambers in the box.
In order to completely prevent air leakage, this rubber gasket is usually made quite thick. The gasket must be soft enough to seal tightly around the extruded tube without creating excessive frictional resistance. The lower the temperature of the cooling medium in the vacuum tank, the higher the suction capacity of the vacuum pump, and part of the working fluid will be discharged with the gas, so the working fluid is constantly replenished, but the water ring vacuum pump cannot be started without water. There are two cooling methods for FRP plastic pipes, one is immersion cooling and the other is spray cooling. Bath type is usually used for small diameter pipes, pipes larger than 110mm in diameter tend to be cooled by spray.
There are 4-6 gears in the submerged cooling water tank, each gear is 2-3 meters long, in order to maintain the temperature gradient and adjust the cooling speed. The cooling water tank should maintain a certain water level, and the cooling temperature can be adjusted by adjusting the flow of cooling water into the water tank. The main problem with immersion cooling is that vertical temperature differences in the tank and the buoyancy of the water can deform the pipes, especially for larger diameter pipes. The spray cooling of the plastic pipe with nozzles evenly distributed along the circumference can significantly improve the cooling intensity, because the water will impact the outer wall of the FRP plastic pipe at a relatively high speed, preventing the formation of a warm water layer at the interface.