Plastics
Vacuum pumps are used in various processes in the plastics industry including degassing, drying, CNC routers and conveying to name a few.
Drying
Before pellets are further processed in an extruder, a pneumatic conveyor (see below) transports them to a dryer through which warm air is circulated from a closed-circuit system. The air in the dryer absorbs moisture from the pellets, which is then evacuated to the outside by means of a hygroscopic agent. Periodically, the drying agent itself must have hot air blown through it in order to regenerate it.
Pneumatic conveying systems
At various stages in the production process, plastic pellets must be transported from one place to another (for example, from the silo to the dryer). This process can be automated and accelerated with a pneumatic conveying system. A pipeline is run from the starting point to the destination and connected to a vacuum pump or compressor. Depending on the bulk weight of the material and length of the pipeline, the system is designed so that the vacuum pump (vacuum conveying) or compressor (pressure conveying) generates enough air speed to pick up the material and convey it to its destination without depositing it in the pipeline. Because pneumatically conveying plastic pellets results in a lot of dust, a filter system is also recommended.
Extraction and compression of vinyl chloride gas
During the production of PVC, liquid vinyl chloride is polymerized under pressure in the autoclave to form polymerized PVC. The gaseous monomers that are also produced are then pumped out, compressed and liquefied.