VAT 642 Series Installation, Operating, & Maintenance Instructions page 40

Gasflow calculation for LEARN:
1. At first it is necessary to find out about the required control range respectively its conductance
values. Each working point (pressure / flow) must be calculated with one following formulas. Choose
the applicable formula depending on units you are familiar with.
C
C
C
Out of these calculated conductance values choose the lowest.
2.
C = min(C
R
3. Calculate gasflow for learn. Choose the applicable formula depending on units you are familiar with.
q =
L
q =
L
= 71 • p
q
L
40/94
Do not apply a different gasflow for learn than determined below. Otherwise pressure
control performance may be insufficient. Required pressure / flow regime must be
known to calculate the most suitable learn gas flow for a specific application.
1000 • q
C
WP
q
=
WP
p
p
WP
C
q
WP
= q
WP
p
p
WP
C
q
WP
= q
WP
78.7 • p
p
WP
C
C C )
WP1, WP2, . . . , WPn
C
To make sure that the valve is capable to control the most extreme working point verify
that CR ≥ Cmin of the valve (refer to «Technical data»).
• C
p
SFS min
1100
• C
p
SFS min
1.1
• C
SFS min
Edition 2017-11-24
INSTALLATION
required conductance of working point [l/s]
WP
gasflow of working point [Pa m3/s]
WP
pressure of working point [Pa]
WP
required conductance of working point [l/s]
WP
gasflow of working point [mbar l/s]
WP
pressure of working point [mbar]
WP
required conductance of working point [l/s]
WP
gasflow of working point [sccm]
WP
pressure of working point [Torr]
WP
required lower conductance [l/s]
R
required conductance of working points [l/s]
WPx
q gasflow for learn [Pa m
L
p sensor full scale pressure [Pa]
SFS
C min. controllable conductance of valve [l/s], (refer to
min
«Technical data»)
q gasflow for learn [mbar l/s]
L
p sensor full scale pressure [mbar]
SFS
C min. controllable conductance of valve [l/s], (refer to
min
«Technical data»)
q gasflow for learn [sccm]
L
p sensor full scale pressure [Torr]
SFS
C min. controllable conductance of valve [l/s], (refer to
min
«Technical data»)
3
/s]
Series 642
605403ED