Venturi Vacuum Generators

Venturi vacuum generators use the flow of motive fluid such as air, steam, or liquid to evacuate air. They include one or more stages of the same technology type (mechanical or Venturi), or two or more different types of pumps packaged together. Single-stage devices move air directly from the chamber into the atmosphere. Two-stage devices evacuate air in two stages for lower absolute pressure. Venturi vacuum generators with three or four evacuation stages are also available. Benchtop models are small enough to sit atop a bench or table. Portable products include wheels, casters, or an easily movable frame for frequent relocation. Larger Venturi vacuum generators are designed to rest on the floor or on a skid. Products that are designed for permanent installation are also available.    

Ultimate operating vacuum and pumping speed are the most important specifications to consider when selecting Venturi vacuum generators. Typically, vacuum is measured in torr or millimeters of mercury (mm Hg) referenced above absolute zero pressure. Venturi vacuum generators provide three levels of ultimate operating vacuum: rough vacuum (1 torr and above), medium vacuum (0.001 to 1.0 torr), and high vacuum (below 0.001 torr). In addition, some suppliers use terms and standards such as medium vacuum and ultra-high vacuum. Pumping speed or displacement is the vacuum pump’s air volume capacity. Vacuum pumps are flow-rated according to the volume of air exhausted with no pressure differential across the pump. 

Venturi vacuum generators may include a control panel, valve sequencing control, vacuum gauge, integral trap, and/or gas ballast. Control panels allow operators to set and adjust parameters and operating conditions. The sequential control of valve opening is especially important in high-vacuum systems. Analog vacuum gauges consist of a meter and a needle. Digital devices provide numeric readouts. Some Venturi vacuum generators include integral traps that prevent backstreaming and resultant contamination from roughing pumps. Although many different trap technologies are available, all are designed to prevent the ingress of substances such as oil, water vapor, and hydrocarbons. Gas ballasts are sometimes used to allow atmospheric air into the compression chamber in order to minimize oil condensation and prevent corrosion.   

Venturi vacuum generators are used in many different applications and industries. Analytical and scientific devices are designed for use with electron microscopes, analytical spectrophotometers, and physics experiments. Products designed for power generation systems are used in condenser venting and vapor recovery. Some Venturi vacuum generators are used in the food processing or chemical processing applications. Others are rated for pharmaceutical and sanitary applications, or designed for semiconductor manufacturing.