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Vacuum and Gas Kinetics
Published in Eiichi Kondoh, Micro- and Nanofabrication for Beginners, 2021
Rotary pump A rotary pump or rotary vane pump is probably the most common vacuum pump. It functions from the atmospheric pressure down to about 100 Pa in the case of single-stage usage. Figure 2.14 is an example of a rotary vane pump. Two vanes attached to a rotor at the center are pressed to the inner wall of a cylinder. As the axis of the rotor is offset from the cylinder axis, the volume of the space bounded by the vanes, the rotor, and the cylinder changes as the rotor rotates. Gas enters when this space has a larger volume, gets compressed with rotation, and is finally exhausted to the outlet port thorough a gas ballast valve. The internal space, such as the cylinder, is filled with oil. The oil serves to seal the outlet valve from leaks and also lubricates the moving parts. The capacity of rotary pumps for laboratory experiments (as well as for semiconductor manufacturing) have a pumping speed of 50–2000 ℓ/min. Rotary pumps are economically affordable, irrefrangible, easy-to-use or -to-maintain, and function from the atmospheric pressure so that no roughening/backing pumps are necessary. For these reasons, rotary pumps are widely used. One serious drawback is oil emission. As the gas directly gets in contact with oil, the oil vapor is easily incorporated to the vacuum which limits the achieving pressure and leads to contamination. The oil must be exchanged regularly as the oil degrades, but usually not so often.
Commercial, Institutional, and Industrial Water Use
Published in Abbas Yari, Saeid Eslamian, Faezeh Eslamian, Urban and Industrial Water Conservation Methods, 2020
The California Urban Water Conservation Council has identified the replacement of liquid ring vacuum pumps with dry vacuum systems as a potential best management practice (PBMP). This investigation was undertaken to assess the potential viability of dry vacuum pump systems as a best management practice (BMP) for urban water purveyors in California. There is significant potential for cost-effective water savings benefits from the adoption of dry vacuum pump technology. This conclusion may be even stronger when wastewater and energy impacts are also included in the benefits analysis. Some California water agencies already have rebate programs for dry vacuum pumps or mechanisms such as customized rebate programs for commercial, institutional, and industrial customers that can handle rebates for dry vacuum systems. Vacuum pumps and systems are presently used in a wide range of commercial and industrial sectors including dental, medical, food handling, processing, packaging, pharmaceutical, chemical, electronics manufacturing, light bulb manufacturing, scientific/laboratory, petroleum, groundwater remediation, pulp, and paper mills and sewage treatment (Fryer 2012).
Compressors and Pumps
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Compressors and pumps, often called working machines, are used to move materials for a large variety of purposes. Compressors are machines that increase the pressure of a gas through input of mechanical work. Vacuum pumps are compressors that operate using suction pressure to create vacuum. Liquid pumps transfer liquids, or sometimes slurries of liquid–solid mixtures. Applications for these machines are in industries such as steel, petroleum, chemical, mining, food, gas, production and storage, energy conversion (refrigeration), etc. Their shutdown means loss in production. Lubricants in these applications lubricate moving parts such as bearings and gears, provide a liquid seal, and remove heat. This can be a difficult task as the lubricant often operates in a hostile environment.
Design and performance evaluation of a pilot-scale pulsed vacuum infrared drying (PVID) system for drying of berries
Published in Drying Technology, 2020
Wei-Peng Zhang, Chang Chen, Zhongli Pan, Hong-Wei Xiao, Long Xie, Zhen-Jiang Gao, Zhi-An Zheng
The selection of vacuum pump should consider all the factors involved in the system, such as pumping speed, vacuum pressure, and pump capacity. The evacuation time is the main criteria for the selection. By assuming that the pilot PVID system was at atmospheric pressure in the beginning, Equation (1) gives the selection method of vacuum pump[30] where V is the effective volume of the drying chamber, L; tp is the roughening time of 2 min. P1 is the atmospheric pressure of 101 kPa; P2 is the vacuum presser of 5 kPa.; Se is the pumping rate, L/min; Ke is the modified factor of a low vacuum system with the value of 2.3; the value of Ke ranges from 2 to 2.5 for different vacuum pressure ranges. The approximate value of pump speed Se can be determined for pump selection.