Kobold MAS Series, Инструкция по эксплуатации

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MAS Instruction Manual
Page 41
will cite the reference gas used. When a reference gas is used, the
actual flow rate will be within 2-4% of the calculated flow rate.
EXAMPLE 1:
A MAS is calibrated for nitrogen (N2), 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:
Q Q K K
CO N CO N
2 2 2 2
0 74 1 000 1000 740
/ / ,
. / .
=
=
( )
=
or
Q SCCM
CO
2
EXAMPLE 2:
A MAS is calibrated for hydrogen (H
2
), and the flow rate is 100
SCCM for a 5,000 VDC output signal. The flow rate for nitrous
oxide (N
2
0) is found as follows:
Q Q K K
N H N H
2 2 2 2
0 0
0 71 1 01 100 70 3
/ / ,
. / . .
=
=
( )
=
or
Q SCCM
N 0
2
Please note that the K-factors relative to nitrogen must be used in
each case.
EXAMPLE 3:
We want a MAS to be calibrated for use with dichlorosilane
(SiH
2
CL
2
) at a 100 SCCM full scale flow. We wish to use the
preferred reference gas Freon-14 (CF
4
). What flow of CF
4
must we
generate to do the calibration?
Q Q K K
Q
Q
SiH CL CF SiH CL CF
CF
CF
2 4 2 2 4
4
4
2
100 0 869
100 0 869 115
/ /
/ .
/ .
=
=
= =
SCCM
Equation (6) is used for gas mixtures, but we must calculate N/rC
P
for the mixture. The equivalent values of r, C
P
, and N for a dual gas
mixture are given as follows:
The equivalent gas density is:
ρ ρ ρ =
( )
+
( )
˙ / ˙ ˙
/ ˙ m m m m
T T 1 2 1 2
(7)
where:
˙ ˙ ˙
m m m
T
= + =
1 2
Total mass flow rate (gm/min),
( )
1
= Refers to gas #1, and
( )
2
= Refers to gas #2.
The equivalent specific heat is:
C
P
= F
1
C
P1
+ F
2
C
P2
For Dual-Gas Mixtures