Model 300E Carbon Monoxide Analyzer
Instruction Manual
THEORY OF OPERATION
P/N 04288 Rev: A
161
10.2. Pneumatic Operation
CAUTION
It is important that the sample airflow system is both leak tight and not
pressurized over ambient pressure.
Regular leak checks should be performed on the analyzer as described in the
maintenance schedule, Table 9-1.
Procedures for correctly performing leak checks can be found in Section 9.5.
10.2.1.
Sample Gas Flow
.
Sample Chamber
Filter
From Sample
Port
Pressure Sensor
(Sample Pressure)
Flow Sensor
(Sample Flow)
PUMP
Critical Flow
Orifice
To
Exhaust Port
Figure 10-7: Model 300E Pneumatic Operation
An internal pump evacuates the sample chamber creating a small vacuum that
draws sample gas into the analyzer. Normally the analyzer is operated with its inlet
near ambient pressure either because the sample is directly drawn at the inlet or a
small vent is installed at the inlet. There are several advantages to this “pull
through” configuration.