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對于真空度的標識通常有兩種方法，一是用對壓力（即：較真空度）標識，二是用相對壓力（即：相對真空度）標識。
There are usually two ways to mark vacuum degree, one is to use absolute pressure (absolute vacuum degree), and the other is to use relative pressure (that is, relative vacuum degree) to mark two.
所謂對壓力是指，真空泵與檢測容器相連，經(jīng)過足夠時間連續(xù)抽氣后，容器內(nèi)的壓力不再繼續(xù)下降而維持某一定值，這時容器內(nèi)的氣體壓力值就是泵的對壓力。如果容器內(nèi)對沒有氣體，那么對壓力就是零，這是理論真空狀態(tài)。在實際情況中，真空泵的對壓力值介于0～101.325kPa之間。對壓力值需要用對壓力儀表測量，在20℃、海拔高度＝0的地方，儀表的初始值為101.325kPa。
The so-called absolute pressure refers to the vacuum pump is connected with the detecting container, after sufficient time for continuous pumping, the pressure within the container will no longer continue to decline while maintaining a certain value, then the pressure in the container is absolute pressure pump. If there is absolutely no gas in the container, then the absolute pressure is zero, which is the theoretical vacuum. In actual situation, the absolute pressure value of vacuum pump is between 0 and 101.325kPa. Absolute pressure values need to be measured with absolute pressure gauges, where the initial value of the instrument is 101.325kPa at 20 and 0 altitude.
相對真空度是指被測對象的壓力與測量地點大氣壓的差值。用普通真空表測量。在沒有真空的狀態(tài)下，表的初始值為0。當測量真空時，它的值介于0到－101.325kPa（一般用負數(shù)表示）之間。比如，測量值為－30kPa，則表示泵可以抽到比測量地點的大氣壓低30kPa的真空狀態(tài)。同一臺泵在不同的地點測量，其相對壓力值可能是不同的，因為不同測量地點的大氣壓是不同的，這是各地的海拔高度、溫度等不同客觀條件造成的。
The relative vacuum refers to the difference between the pressure of the measured object and the atmospheric pressure at the measuring point. Measuring with an ordinary vacuum gauge. In the absence of vacuum, the initial value of the table is 0. When measuring the vacuum, its values ranging from 0 to 101.325kPa (generally express with the negative number). For example, the measured value is 30kPa, said pump can be pumped into the vacuum measurement locations than the low atmospheric pressure 30kPa. The same pump is measured at different locations, and the relative pressure values may be different, because the atmospheric pressure at different measuring sites is different, which is caused by different objective conditions, such as altitude and temperature in different places.
國際真空行業(yè)通用的、也是比較科學的是用對壓力標識；由于測量相對真空度的方法簡便、測量儀器非產(chǎn)普遍、容易買到且價格便宜，因此它也得到廣泛應用。當然，理論上二者是可以相互換算的。換算方法如下：對壓力＝測量地點的氣壓－相對壓力。
The vacuum industry general, is also the most scientific is the identity with the absolute pressure; the method for measuring relative vacuum degree measuring instrument is simple, non universal, easily available and cheap, so it has been widely used. Of course, in theory, the two can be converted into one another. The conversion method is as follows: absolute pressure = pressure relative pressure at the measuring site.
