Air extraction
The
pumping volume is a measure factor of the pumping speed of vacuum pump. General
units are L / s and m ³/ H. It is a parameter to make up for the air leakage
rate. It is not difficult to understand why a vacuum pump with large air volume
can easily pump the vacuum we need, while a vacuum pump with small air volume is
very slow or even unable to pump the vacuum we want? The pipeline or container
can never be absolutely free of air leakage, and the large air extraction makes
up for the decrease of vacuum caused by air leakage, and the air volume can
easily reach the ideal vacuum value.
Vacuum pump
vacuum degree
It
indicates the degree of gas dilution under vacuum, which is usually expressed by
pressure value. The vacuum degree value indicates that the actual value of the
system pressure is lower than the atmospheric pressure. The value expressed from
the table is also called the table pressure, which is also called the limit
relative pressure in the industry. In practical application, the vacuum degree
usually has two versions: absolute vacuum and relative vacuum. The value read
from the vacuum gauge is called vacuum degree. Vacuum degree = atmospheric
pressure - absolute pressure (the atmospheric pressure is generally 101325pa,
and the ultimate absolute pressure of water ring vacuum pump is 3300pa; Limit
absolute pressure of rotary vane vacuum pump (about
10Pa)
Vacuum
Theoretically, it means that there is no substance in the
volume. In reality, there is no real vacuum. Generally, the pressure in the
container lower than the normal atmospheric pressure (101325 PA) is called
vacuum state.
Absolute vacuum and relative vacuum
Limit relative
pressure
The relative pressure is how much lower the measured internal
pressure is than the "atmospheric pressure". It shows that the actual value of
system pressure is lower than the value of atmospheric pressure. Because the air
inside the container is pumped, the internal pressure is always lower than the
external pressure of the container. When expressed by relative pressure or gauge
pressure, the value must be preceded by a negative sign, indicating that the
internal pressure of the container is lower than the external
pressure.
Ultimate absolute pressure
Absolute pressure is how much higher
the measured internal pressure is than "theoretical vacuum (theoretical vacuum
pressure value is 0Pa)". It compares the absolute vacuum pressure of the
theoretical state. Due to the limitation of process, we can't pump the internal
pressure to the value of absolute vacuum 0Pa in any case. The vacuum value
pumped by the vacuum pump is higher than the theoretical vacuum value.
Therefore, when expressed in absolute vacuum, there is no negative sign in front
of the value.
8/17/2021
Do you know the vacuum degree of the vacuum pump?
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