Vertical oil-free vacuum pumps and screw vacuum pumps

The development of various vacuum pumps is increasingly influenced by the requirements of vacuum applications. Conventional vacuum systems fail to meet the demands for cleanliness, oil-free operation, and corrosion resistance; as a result, there has been a high demand for dry vacuum pumps in recent years. Vacuum generation technologies have undergone updates, with many oil-based vacuum systems being replaced by oil-free, clean vacuum systems. Almost every major vacuum company abroad produces various types of dry vacuum pumps. Screw vacuum pumps are a type of non-contact dry pump; they emerged in the early 1990s and have become an ideal choice due to their wide range of pumping speeds, simple and compact design, friction-free components in the pumping chamber, long service life, low energy consumption, and absence of oil contamination. Due to their excellent performance, dry screw vacuum pumps have become the preferred vacuum generation equipment in industries such as microelectronics, semiconductors, pharmaceuticals, and precision manufacturing in Europe, the United States, and Japan. Building on screw compressors, Japan developed multi-rotor rotor designs for vacuum pumps at an early stage and brought them to market. Several German vacuum equipment manufacturers have also gradually developed rotor profiles with equal and variable pitch, and have conducted extensive research on rotor and chamber cooling. In 2008, Chinese companies also began mass production of screw vacuum pumps, which have found wide use in industries such as chemicals and pharmaceuticals.

What kind of vacuum pump is suitable for evacuating carbon tetrachloride, given that there may be some hydrogen chloride present? I plan to add a compressor after the vacuum pump in order to recycle the exhaust gases

Don’t be misled by the name; the “oil-free” in vertical “oil-free” vacuum pumps is merely an adjective, indicating that very little lubricating oil is used… not oil-free in a strict sense! Screw vacuum pumps and reciprocating pumps are not comparable, as this is determined by their working principles. The working principle of screw vacuum pumps ensures that there is no contact within the working chamber, hence no friction at all – which means they are completely oil-free!

The difference is quite significant: 1. The ultimate vacuum level can vary by 2000–3000 Pa, and the vacuum levels required for certain processes cannot be achieved at all using oil-free vertical reciprocating vacuum pumps. 2: The safety levels are different; oil-free vertical reciprocating vacuum pumps pose a significant risk in flammable and explosive environments, but screw vacuum pumps are different. 3: Usability. Screw vacuum pumps require little maintenance, with almost no wear parts that need to be replaced frequently; in contrast, reciprocating pumps have valves that need to be replaced often, which makes them less convenient to use. 4: Land area. Screw vacuum pumps take up little space. There are many other differences as well. The domestic screw vacuum pumps made by Teyner perform well; they are much cheaper than those imported, have fewer malfunctions, and are quite useful.

Screw vacuum pumps also come in different types, and not all pump manufacturers produce the same ones. The ESDP dry screw vacuum pump features a unique screw rotor profile, which results in 30% less energy consumption, a low exhaust temperature, and process stability. These dry screw pumps are suitable for vacuum applications in various fields, offering excellent vacuum efficiency and durability. The ESDP series does not use oil or water; it operates via variable compression and a mixture of steam and liquid, making it highly suitable for various vacuum applications such as drying, solvent recovery, the chemical industry, pharmaceuticals, and plastics. The SDP series of products are dry screw vacuum pumps with a single-stage direct-connected structure. The screw vacuum pumps in this series can be used in a variety of vacuum processing operations in general industrial fields, such as drying and concentration processes in the chemical and pharmaceutical industries ； Especially during the reaction, extrusion, and distillation processes of synthetic resins, the SDP series maintains **excellent performance due to the absence of contamination.

Oil-free means that no oil is required in the pump chamber for lubricating and sealing; these are pure dry-type pumps, such as screw pumps and claw pumps. Currently, Edward Vacuum’s various dry-type pumps are used in semiconductor manufacturing processes, as well as in various chemical industries including petrochemicals, refining, and oil chemistry. They feature designs that enable low energy consumption, environmental protection, as well as resistance to corrosion and explosions. Currently, in the pharmaceutical industry, many vertical claw-type pump systems have been in use for over 30 years, and there are also cases where they have been used in HF applications for more than 15 years. At present, Sihi is the one manufacturing vertical screw pump structures, while the Edward company is capable of producing pumps with vertical claw structures. Many domestic brands also appear to have a claw structure or a vertical screw structure, but their durability does not exceed 2 or 3 years, and there are still significant shortcomings in the design of many details. Many screw pumps use various resins or Ni coatings, with a service life of no more than 3–5 years. These coatings struggle to withstand particles in harsh chemical environments; once they wear off, the pumps suffer severe corrosion under corrosive conditions. Moreover, the cost of repairing such coatings is high, and it is difficult to ensure that the pumps will maintain their performance after repair. The pumps produced by the Edward company feature a purely dry-type claw structure and screw structure, and corrosion prevention is achieved through precise temperature control. It features overall explosion protection. I have also compared some domestic products with these ones in the past; you get what you pay for. To mention just one point: when it comes to capacity, the installed power is roughly 50% higher than that of Edward’s products. Only through long-term practice and application can a design that is continuously improved meet the requirements. Domestic products still have a long way to go. Currently, Edward has established factories in Qingdao and Tianjin, where costs, delivery times, and service quality have been further improved.