Principles Of Operation; Basic Principles Of Dynamic Dilution Calibration - Teledyne T700 Operation Manual

PRINCIPLES OF OPERATION

10.
10.1. BASIC PRINCIPLES OF DYNAMIC DILUTION
CALIBRATION
TOTALFLOW = GAS
06873B DCN6388
The T700 Dynamic Dilution Calibrator generates calibration gas mixtures by mixing
bottled source gases of known concentrations with a diluent gas (zero air). Using
several Mass Flow Controllers (MFCs) the T700 calibrator creates exact ratios of diluent
and source gas by controlling the relative rates of flow of the various gases, under
conditions where the temperature and pressure of the gases being mixed is known (and
therefore the density of the gases).
The CPU calculates both the required source gas and diluent gas flow rates and controls
the corresponding mass flow controllers by the following equation.
C =
f
WHERE:
C = final concentration of diluted gas
f
C = source gas concentration
i
GAS = source gas flow rate
flow
Totalflow = the total gas flow through the calibrator
Totalflow is determined as:
TOTALFLOW = GAS
WHERE:
GAS = source gas flow rate
flow
Diluent = zero air flow rate
flow
For instrument with multiple source gas MFC total Flow is:
+ GAS
flow MFC1
GAS
flow
C ×
i
Totalflow
+ Diluent
flow
...+ GAS
flow MFC2
Equation 10-1
Equation 10-2a
flow
Equation 10-2b
+ Diluent
flow MFCn flow rate
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