Flow Rate Control - Teledyne T300 Operation Manual

Theory of Operation
SAMPLE GAS
INLET
EXHAUST
GAS OUTLET
PUMP
Figure 13-7:

13.3. FLOW RATE CONTROL

304
•
By placing the pump down stream from the sample chamber several problems are
avoided.
•
First the pumping process heats and compresses the sample air complicating the
measurement process.
•
Additionally, certain physical parts of the pump itself are made of materials that
might chemically react with the sample gas.
•
Finally, in certain applications where the concentration of the target gas might be
high enough to be hazardous, maintaining a negative gas pressure relative to
ambient means that should a minor leak occur, no sample gas will be pumped into
the atmosphere surrounding analyzer.
Particulate Filter
Flow / Pressure
Sensor PCA
Sample Gas
Flow Control
Internal Pneumatic Flow – Basic Configuration
To maintain a constant flow rate of the sample gas through the instrument, the
T300/T300M uses a special flow control assembly located in the exhaust gas line just
before the pump. In instruments with the O
assembly is located between the O
consist of:
•
A critical flow orifice.
•
Two o-rings: Located just before and after the critical flow orifice, the o-rings seal the
gap between the walls of assembly housing and the critical flow orifice.
•
A spring: Applies mechanical force needed to form the seal between the o-rings, the
critical flow orifice and the assembly housing.
Teledyne API – Model T300/T300M CO Analyzer
GFC Wheel
SAMPLE CHAMBER
SAMPLE
PRESSURE
SENSOR
FLOW
SENSOR
sensor installed, a second flow control
2
sensor assembly and the pump. These assemblies
2
INSTRUMENT CHASSIS
GFC Motor Heat Sync
Housing
06864B DCN6314