The concept of evaporating vacuum
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When discussing the issue of evaporation, fellow seafarers often talk about vacuum, but each has its own concept of vacuum and vacuum degree.* As is customary, some people say that high vacuum means low absolute pressure, while others mean high absolute pressure. When it comes to high vacuum, it means different things than low vacuum. Causing conceptual confusion. Let’s take absolute pressure as an example. Absolute pressure is high: What is the corresponding vacuum and vacuum degree? The absolute pressure is low: What is the corresponding vacuum and vacuum degree? Please discuss, and finally ask the moderator to give an authoritative answer. On the one hand, this is theory * , on the other hand, we can have a unified understanding and express clearly and intuitively when discussing the issue of negative pressure.
Degree of vacuum = atmospheric pressure - absolute pressure. When we say a high degree of vacuum, it means a high absolute pressure, and vice versa, it means a low absolute pressure.
Vacuum degree = atmospheric pressure - absolute pressure. The higher the vacuum degree, the lower the absolute pressure.； The lower the vacuum, the higher the absolute pressure. There shouldn't be any doubt about this. This post was last edited by ttlkk on 2009-2-22 13:55 ]
Degree of vacuum = atmospheric pressure - absolute pressure. It can be seen from the above relationship that the higher the degree of vacuum, the lower the absolute pressure.； On the contrary, when the vacuum degree is low, the absolute pressure is high. There shouldn't be any doubt about this.
Vacuum is a state in which the absolute pressure is less than atmospheric pressure. Vacuum and negative pressure should represent the same concept. It can be expressed in terms of absolute pressure or vacuum. The degree of vacuum is a numerical value that represents the size of the vacuum, which is equal to the atmospheric pressure minus the absolute pressure. The relationship between the absolute pressure and the absolute pressure is that you are bigger and I am smaller, and you are smaller and I am bigger.
To put this in layman's terms, when expressing a vacuum, I can use the pressure of the container itself (that is, absolute pressure), and then I can also use the gauge outside the container to see the reading (this is the gauge pressure, no matter whether your container is higher than atmospheric pressure or lower, I will use it to express it). If your actual container is lower than atmospheric pressure, it means that the actual pressure of your container is low, and the outside gauge can also judge it. If it is negative, it means that your container is actually under pressure. The actual pressure is lower than the atmosphere, for example, 10kpa. Then the actual container pressure is 90kpa. If the gauge pressure is 1MPA, it means that your actual container pressure is higher than the atmospheric pressure, which is 2MPA. To sum up, there are two ways to express pressure, which are actual pressure, gauge pressure or vacuum gauge. I regard it directly as the "inside" of the actual pressure vessel, while the gauge pressure is the "outside" of the vessel. Only the form is different! I don’t know, right? Corrections welcome