The issue with system vacuum
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Dear everyone, I am currently working on the selection of equipment for vacuum systems, and there are several issues that have left me confused. I would like to ask for your advice; I hope you will kindly share your insights: (1) Is the ultimate vacuum level of the system determined by the saturated vapor pressure of the working fluid under that condition? In other words, no matter what type of vacuum pump is used, the vacuum level cannot be lower than its saturated vapor pressure? (2) Vacuum pumps generally have technical performance parameters; how is the ultimate vacuum level mentioned calculated? Since the process for this project is a new type of process and there are no detailed operational data available, everything has to be figured out through trial and error. So how can I achieve a balance between the selection of the vacuum pump and the design vacuum level required by the system? Thank you all!
The first issue generally relates to liquid ring pumps; theoretically, the maximum vacuum that can be achieved with a water ring pump is equal to the saturated vapor pressure of water at its operating temperature. The vacuum level can be increased by lowering the water temperature, for example by adding ice to it. The second question: regardless of whether you have other parameters or not, as a process engineer you certainly know the vacuum level required for the process, as well as the required pumping capacity in terms of liters per hour. You also need to know what medium is to be evacuated. With these basic parameters, you can directly consult suppliers, who will generally provide you with suggestions. Of course, you can also choose the pump yourself; keep in mind that the capacity of the vacuum pump chosen should be one order of magnitude higher than the vacuum level required by the process, and taking into account the effects of the medium will help you make an initial selection.
The ultimate vacuum level depends on the vacuum pump – that is, the highest level of vacuum that can be achieved in the absence of any gases – and it is entirely determined by the vacuum pump.
The ultimate vacuum level depends on the vacuum pump – that is, the highest level of vacuum that can be achieved in the absence of any gases – and it is entirely determined by the vacuum pump. For example, a micro vacuum pump with weak pumping capacity can only reduce the gas pressure inside a sealed container from 100 KPa at normal conditions to 95 KPa even after an infinitely long time; thus, 95 KPa represents the ultimate vacuum level that this pump can achieve. On the other hand, a micro vacuum pump with strong pumping capacity can reduce the pressure from 100 KPa to 10 KPa, and in this case, 10 KPa is the ultimate vacuum level achievable by this pump.