Photometer Electronic Operation; Figure 10-21: O - Teledyne T700 Operation Manual

Teledyne API – Model T700 Dynamic Dilution Calibrator

10.7.4. PHOTOMETER ELECTRONIC OPERATION

Photometer
Sample Gas
Pressure
Sensor
Photometer
Detector
Preamp
Photometer
Detector
Photometer
06873B DCN6388
flow control assembly containing a critical flow orifice directly upstream of the pump
but down stream from the absorption tube.
The critical flow orifice installed in the pump supply line is tuned to create a flow of 800
3
cm /min. A pressure sensor and a flow sensor, located on the O
pressure flow sensor PCA, monitor the pressure and flow rate of the gas passing through
the photometers absorption tube.
See Figure 10-17 and Figure 10-18 for depictions of the airflow related to the
photometer.
MOTHERBOARD
A/D
Converter
Thermistor Interface
Photometer
Sample Gas
Temperature
Absorption tube
Photometer
Lamp Heater

Figure 10-21: O

Photometer Electronic Block Diagram
3
Like the O generator, the O
3
devices operated by the CPU via the motherboard. Communications to and from the
CPU are handled by the motherboard.
Outgoing commands for the various devices such as the photometer pump, the UV lamp
power supply, or the UV Lamp heater are issued via the I
PCA which turns them ON/OFF. The CPU also issues commands over the I
cause the relay PCA to cycle the measure/reference valve back and forth.
Incoming data from the UV light detector is amplified locally then converted to digital
information by the motherboard. Output from the photometers temperature sensors is
also amplified and converted to digital data by the motherboard. The O
of the sample gas is computed by the CPU using this data (along with gas pressure and
flow data received from the T700's pressure sensors.
2
I C Bus
RELAY PCA
2
y
I C
Status
Photometer
LED
UV Lamp
Temperature
Photometer
Lamp Power
Supply
photometer and its subcomponents act as peripheral
3
Principles of Operation
generator/photometer
3
PC 104
CPU Card
Disk on
Module
Flash
Chip
Photometer M/R
Valve
(Located on 0
3
Generator Assembly)
Photometer
Pump
2
C bus to circuitry on the relay
concentration
3
2
C bus that
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