3 AFC, APC
3.4 AFC and APC control
40
GC-2010 Plus
3.4.5 Control by APC
The APC performs its control as illustrated in the figure below.
Fig. 3.4.4
As shown in Fig.3.4.4, the APC controls the pressure.
The flow rate is calculated based on resistance and pressure.
For example, for a flow rate of 400 ml/min of air, the pressure is controlled and set to
approximately 61 kPa based on the pressure-flow rate characteristics of air stored in the
memory of the GC-2010 Plus. (Refer to Fig. 3.4.5)
The resistance depends on the detector type and the gas type (air, hydrogen or makeup
gas).
Fig.3.4.5-3.4.8 show the pressure-flow rate characteristic curves of the standard restrictor.
AUX APC offers “PRESS” and “FLOW” mode.
When the Control mode is “PRESS”, AUX APC controls the pressure as shown in Fig.3.4.4.
When the Control mode is “FLOW”, the pressure is calculated based on the set flow rate,
calculated from the restrictor inner diameter, and length. (Refer to column flow rate in “3.2
Definition of Terms”.) The equation in 3.2 is accurate when the flow in the restrictor is layer.
Therefore, the flow rate accuracy depends on the restrictor used.
Fig. 3.4.5
GAS IN
Valve
Pressure sensor
Resistance
To detecto
Air
Pressure (kPa)
Flow rate (ml/min)
0 20 40 60 80 100 120 140 160
0
100
200
300
400
500
600
700
800
900
1000
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