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*P
relationship given above.
simr
ar to the dual-gas
,
and N for mixtures of
more than two gases have a form
m,)N,
The equivalency relationships for p, C
/
(br2
in,)N, +
/
cm,
=
(fi,
P
)
The equivalent value of N is: N
/
P,)
(fi2
F,
=
1%
P
) and
/
)
P,
(rf+
C,
where: F,
=
F,
Cp,
+
=
F, C,
#2
The equivalent specific heat is:
=
refers to gas
)*
,
and (
#l
=
refers to gas
),
(
(grn/min),
=
Total mass flow rate
rh,
61,
+
=
rir,
a
where:
p,
(7)
t?~,)
(I$/
p,
+
61~)
/
(6,
=
p
C,
and N for a
dual gas mixture are given as follows:
The equivalent gas density is:
p,
pC, for the mixture. The equivalent values of
N/
100/0.869=115SCCM
Equation (6) is used for gas mixtures, but we must calculate
QCF’
=
QCF’
= 0.869
/
KcF,,
100
/
KsiH2Ch
QCF’
=
/
QSIH~C~
CF,
must we generate to do the calibration?
(CF,).
What flow of
preterred
reference gas Freon-14
(SiH
CL,) at a 100 SCCM full scale
flow. We wish to use the
/
1 .Ol) 100 = 70.3 SCCM
Please note that the K-factors relative to nitrogen must be
used in each case.
EXAMPLE 3: We want a flow controller to be calibrated for
use with dichlorosilane
QN*O
=
(0.71
KH*,
or
/
KN*O
QH*
=
/
QN*O
found.as follows:
(N,O)
is
(H,)
and the flow rate is 100 SCCM for a 5.000 VDC output signal.
The flow rate for nitrous oxide
=
740 SCCM
EXAMPLE 2: A flow controller is calibrated for hydrogen
/
1 .OOO) 1000
Qco,
= (0.74
KN*,
or
/
Kco,
=
QN*
/
Qco,
(N,)
and the flow rate is 1000 SCCM for a 5.000 VDC output signal.
The flow rate for carbon dioxide at a 5.000 VDC output is:
EXAMPLE 1: A flow controller is calibrated for nitrogen