Series 810 Instruction Manual
Appendix A
Example 1:
A transducer is calibrated for nitrogen (N
2
), 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
CO2
/Q
N2
= K
CO2
/K
N2
, or
Q
CO2
= (0.74/1.000)1000 = 740 sccm
Example 2:
A transducer 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
O) is
found as follows:
Q
N2O
/Q
H2
= K
N2O
/K
H2
, or
Q
N2O
= (0.71/1.01) 100 = 70.3 sccm
Note that the K -factors relative to nitrogen must be used in each case.
Calculating Dual Gas Mixtures
Equation (6) is used for gas mixtures, but we must calculate N/
ñ
C
p
for the
mixture. The equivalent values of
ñ
, C
p
, and N for a dual
gas mixture are given as follows:
The equivalent gas density is:
ρ = ( m 1
m
/ T P 1 ) 4
l T
P 2 / )
Where:
•
•
m
T
= m
1
+ 1
11
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
= F1Cp1 + F2Cp2
Where:
F1 = (11
1
1 P1)/(l"
T
P) and
F2= (m2)/("'T ρ)
The equivalent value of N is:
L
Ν = ( j 1 m ~ 1 ) Ν m 2 + T
4
2 / ) Ν
IM-81
A-3
