Classification and Applicable Range of Vacuum Gauge
In
pressure measurement, except for a few direct measurements, most of them are
indirect measurements. It is to cause a certain physical phenomenon in the
measured gas, and then measure the physical quantity related to the pressure in
this process, and then try to determine the pressure value. This is the
characteristic of vacuum measurement, and will cause some problems.
1. A
vacuum gauge is an instrument for measuring the pressure of a gas or vapor
below an atmospheric pressure.
2. Absolute vacuum gauge is an instrument which can directly calculate (or get)
the pressure from the physical quantity measured by the vacuum gauge itself.
3.
The relative vacuum gauge can only be measured after being calibrated by the
absolute vacuum gauge.
Therefore,
any method has a certain measurement range, which is the "range" of
the vacuum gauge. It is one of the important contents of vacuum scientific
research to expand the range of each method as much as possible. Modern vacuum
technology involves a pressure range of 19 orders (105-10-14 PA). No vacuum
gauge can measure such a wide pressure range, so several vacuum gauges are
always used to govern certain areas. However, due to the difference in
principle of various vacuum meters, large errors are often caused in the areas
where they connect with each other. From the above point of view, in order to
improve the performance of vacuum gauge and improve the accuracy of vacuum
measurement, it is necessary to highlight the main phenomenon and suppress the
parasitic phenomenon. Table 1 shows the pressure measurement ranges of some
vacuum gauges.
At high pressure (105-1pa), U-tube pressure gauge, mclaw vacuum gauge, membrane
gauge, spring tube pressure gauge, etc. are used. In the middle pressure range
of 103-10-2 PA, a piezometer and a viscous vacuum meter are made by using the
change of gas properties (heat conduction and viscosity). At low pressure, an
ionization vacuum gauge is used to measure the ionization of gas molecules.
Applicable
pressure range of vacuum gauge
Name
of vacuum gauge measurable pressure range (PA)
Mercury
manometer (U-tube) 10 ^ 5-10 ^ 2
Oil
pressure gauge (U-tube) 10 ^ 5 ~ 10 ^
2
Oil
pressure gauge (U-tube) 3 * 10 ^ 3 ~
1
Mclaw
vacuum gauge (general type and special type) 10 ^ 3 ~ 10 ^ 3
Elastic
deformation vacuum gauge 10 ^ 5 ~
10 ^ 2
Diaphragm
vacuum gauge (mechanical type) 10 ^ 5 ~
10 ^ 2
Diaphragm
vacuum gauge (electrical type) 10 ^ 5 ~
10 ^ 3
Ionization
vacuum gauge (triode type) 10 ^ - 1 ~
10 ^ - 5
B-A
type 10 ^ - 2 ~ 1 ^ - 6 for
ultra high vacuum
Hot
cathode magnetometer for very high vacuum
For
high vacuum (Schulz type) 10 ~ 10 ^
- 2
Cold
cathode vacuum gauge 1-10 ^ - 5
Pirani
vacuum gauge 10 ^ 4 ~ 10 ^
2
Thermocouple
vacuum gauge 10^2 ~
10^-1
Thermistor
vacuum meter 10 ^ 2 ~ 10 ^
1
Viscosity
vacuum gauge 1-10 ^ - 5
Knuzeng
vacuum gauge
评论
发表评论