The process of selecting a vacuum system involves evaluating several types of systems. There are many options for ejector systems, mechanical systems, and rotary vein and vacuum degassing. No one system works best for all applications. It is important to establish guidelines and parameters that allow for rational selection.
One consideration is not sufficient. It is important to consider the interrelationships between many factors before ordering equipment. These are the questions engineers need to ask when selecting the vacuum leak detectors:
What are the Major Operational Considerations?
First, the required suction pressure is a consideration. The liquid-ring vacuum pump rebuilding works in the range of atmospheric pressure to 50 Torr. It cannot, therefore, be used for higher vacuum applications. Multistage ejector systems, however, can operate at.02 Torr. Some piston and rotary pumps can operate at even higher vacuums.
What utilities are available?
If steam is not available, a mechanical system may be necessary. However, some combination systems can use air as an ejector fluid. An ejector system is good if steam is available at a low price as a byproduct stream. A combination ejector/liquid ring pump that uses both low-pressure motive steam and electricity is an option if the byproduct steam has low pressure.
What are the Suction Load Characteristics?
What are the characteristics of the suction load? Some vacuum systems are more forgiving than others. They are better at handling wet suction loads and less susceptible to corrosives and abrasives.
Is the system to be used on a steady or intermittent basis?
It is more expensive to run a vacuum system continuously than if it is only used occasionally. A process engineer might choose a low-cost steam jet ejector for intermittent usage, believing that the greater utility consumption would not be significant occasionally. It is easier to save long-term money if you use the system for a longer period, all other things being equal.
Can the system be used for one, several, or many different processing operations?
For specific processing operations, a mechanical system might be a good choice. Ejectors can be used for “house vacuum” operations (where multiple services are required) because they are less affected by wet loads, corrosive gases, and other hazards that may arise when performing a range of services.
