Photometer O3 Generator Pressure/Flow Sensor Assembly - Teledyne T700 Operation Manual

Teledyne API – Model T700 Dynamic Dilution Calibrator
9.4.10. PHOTOMETER O3 GENERATOR PRESSURE/FLOW SENSOR
ASSEMBLY
06873E DCN7106
This assembly is only present in calibrators with O
installed. The pressure/flow sensor PCA, located at the rear of the instrument between
the O generator and the photometer pump (see Figure 3-6) can be checked with a
3
Voltmeter. The following procedure assumes that the wiring is intact and that the
motherboard as well as the power supplies are operating properly:
BASIC PCA OPERATION

Measure the voltage across C1 it should be 5 VDC ± 0.25 VDC. If not, then the
board is bad.

Measure the voltage between TP2 and TP1 C1. It should be 1o VDC ± 0.25 VDC. If
not then the board is bad.
PHOTOMETER PRESSURE SENSOR
1. Measure the pressure on the inlet side of S1 with an external pressure meter.
2. Measure the voltage across TP4 and TP1.

The expected value for this signal should be:
Expected mVDC
EXAMPLE: If the measured pressure is 20 In-Hg-A, the expected voltage level between
TP4 and TP1 would be between 2870 mVDC and 3510 mVDC.
EXAMPLE: If the measured pressure is 25 In-Hg-A, the expected voltage level between
TP4 and TP1 would be between 3533 mVDC and 4318 mVDC.

If this voltage is out of range, then either pressure transducer S1 is bad, the board is
bad or there is a pneumatic failure preventing the pressure transducer from sensing
the absorption cell pressure properly.
O GENERATOR PRESSURE SENSOR
3
1. Measure the pressure on the inlet side of S2 with an external pressure meter.
2. Measure the voltage across TP5 and TP1.

Evaluate the reading in the same manner as for the cal gas pressure sensor
(see Section 9.4.9).
PHOTOMETER FLOW SENSOR

Measure the voltage across TP3 and TP1.

With proper flow (800 cm3/min through the photometer), this should be
approximately 4.5V (this voltage will vary with altitude).

With flow stopped (photometer inlet disconnected or pump turned OFF) the
voltage should be approximately 1V.

If the voltage is incorrect, the flow sensor S3 is bad, the board is bad or there is
a leak upstream of the sensor.
3
(
Pressure
= x
4660
30.0
In-Hg-A
Troubleshooting and Service
generator and/or photometer options
)
± 10%
+
250
mvDC mvDC
rdg
247