Photometer O 3 Generator Pressure /Flow Sensor Assembly - Teledyne T750 User Manual

P
HOTOMETER
This assembly is present in calibrators with the O
The pressure sensor/flow sensor PCA, located on the inside of the outputs panel next to the
Motherboard, can be checked with a voltmeter. The following procedure assumes that the
wiring is intact and that the motherboard and the power supplies are operating properly:
B PCA
ASIC
1. Measure the voltage across C1; it should be 5 VDC ± 0.25 VDC.
•
2. Measure the voltage between TP2 and TP1 C1; it should be 10 VDC ± 0.25 VDC.
•
P
HOTOMETER
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 Hg-in-A, the expected voltage level between
EXAMPLE: If the measured pressure is 25 Hg-in-A, the expected voltage level between
•
O G
ENERATOR
3
1. Measure the pressure on the inlet side of S2 with an external pressure meter.
2. Measure the voltage across TP5 and TP1.
•
P
HOTOMETER
1. Measure the voltage across TP3 and TP1.
•
•
•
144
O G P
ENERATOR RESSURE
3
:
OPERATION
If not then the board is bad.
If not then the board is bad.
P S (A
RESSURE ENSOR
(
Pressure
=
30.0
TP4 and TP1 would be between 2870 mVDC and 3510 mVDC.
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.
P S (G
RESSURE ENSOR
Evaluate the reading in the same manner as for the Cal Gas Pressure
Sensor.
F S :
LOW ENSOR
With proper flow (800 cc /min through the photometer), this should be
3
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.
/F S
LOW ENSOR
generator and/or photometer installed.
3
P ):
BSOLUTE RESSURE
)
x +
4660 250
mvDC
In-Hg-A
P ):
AUGE RESSURE
A
SSEMBLY
± 10%
rdg
mvDC
083730750B DCN8606