DESIGN AND FUNCTION
Series 642
12/94
Edition 2017-11-24
605403ED
3.2.1
Pressure control system overview and function
Vacuum pressures are always absolute pressures unless explicitly specified as pressure differences.
Example: Downstream control
1 Valve
2 Process chamber
3 Gas inlet
4 Pressure sensor(s)
5 Sensor cable
6 Controller and actuator
7 Cable to remote control unit
8 Cable to power supply
9 HV Pump
S
eff
Q / p
S
eff
effective pump speed (ls
-1
)
Q Gas flow (mbar)
p Pressure (mbar)
or units used in USA
S
eff
= 12.7 • Q / p
S
eff
effective pump speed (ls
-1
)
Q Gas flow (sccm)
p Pressure (mTorr)
M
3
4
5
7
8
2
1
9
Q
p
V
Seff
6
