Ulvac GP-1GRY - Accuracy of Pirani Vacuum Gauge

APPENDIX
- 21 -
5.3. Accuracy of Pirani Vacuum Gauge
The relationship between pressure and output of a Pirani vacuum gauge is nonlinear and its accuracy
range varies with pressure values. To express the outgoing inspection criterion for a Pirani vacuum
gauge, it is defined as "within ± 3% of 100% full scale as converted to the linear scale " and is given
in the instruction manual as measurement accuracy.
To express the error range by pressure values
The pressure and recorder output of the GP-1G(RY) is in proportion to the controller meter scale
graduations, as shown by the recorder output characteristic table (graph).
What is meant by "within ± 3% of 100% full scale as converted to the linear scale " is that an error of
± 3% of the linear scale is involved when the meter S range scale is replaced by a linear scale of
100% full scale.
To express the error range at a reference pressure of 40 Pa (0.4Torr) by pressure value, it is 32 to 49
Pa (0.33 to 0.48Torr), which is ± 3% as converted to a linear scale, as shown in Fig. 8.
Fig. 8 Linear memory conversion
The "Error Range of Pirani Vacuum Gauge" table is given for reference.
Indicated Values (Pa) Working Standard(Pa) Indicated Values (Pa)
Working Standard
(Pa)
0.4
0
-
3
100
83
-
120
2
0
-
5
200
170
-
230
5
2
-
8
400
345
-
465
10
7
-
14
600
510
-
715
20
14
-
26
1000
825
-
1250
40
32
-
49
2000
1650
-
2900
60
49
-
71
2700
1920
-
3750
Indicated Values
(Torr
)
Working Standard
(Torr)
Indicated Values (Torr)
Working Standard
(Torr)
0.003
0
-
0.02
1
0.85
-
1.2
0.01
0
-
0.03
2
1.7
-
2.3
0.05
0.03
-
0.08
3
2.6
-
3.5
0.1
0.07
-
0.13
4
3.4
-
4.6
0.2
0.14
-
0.26
6
5.0
-
7.2
0.4
0.33
-
0.48
10
8.0
-
13
0.8
0.68
-
0.92
20
15
-
27