52
SCD and NCD User Manual
4
Operation
Typical Operating Conditions
lists the recommended starting conditions for SCD and
NCD methods. These conditions should provide acceptable
results for a wide variety of applications. However, optimize
these conditions as needed to improve the performance of the
specific application.
The checkout methods for the SCD and NCD also provide
example parameters for balancing good detection limit, good
selectivity, and reasonable ceramic tube life. In any XCD
method:
•
Always keep oxidizer gas flowing through the burner.
•
The firmware will not allow hydrogen to flow into the burner
while there is no oxidizer to protect the system.
During startup and shutdown, always turn on the pump first
and turn off the pump last to prevent contamination or damage.
Table 6
Typical operating conditions, SCD and NCD
Parameter
SCD
NCD
Base temperature, °C
250
250
Burner temperature, °C
800
900
Chiller temperature
N/A
On
Upper H
2
flow, mL/min
40
N/A
Lower H
2
flow, mL/min
10
3
Oxidizer flow, mL/min
50, Air
8, Oxygen
O3 Generator flow, mL/min
On
On
O3 Generator high voltage
On
On
Vacuum pump
On
On
Burner pressure, Torr, typical reading
< 425 Torr
< 120 Torr
Reactor pressure, Torr (read only)
Should be below
7 Torr
Should be below
5 Torr