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Determining the Total Flow for GPT Calibration Mixtures
The total flow rate is defined by the user depending on system requirements.
The minimum total flow should equal 150% of the flow requirements of all of the
instruments to which the T750 will be supplying calibration gas.
Example:
If the T750 will be expected to supply calibration gas mixtures simultaneously to
a system composed of three analyzers, each requiring 2 SLPM, the proper Total
Note
G
>GPTZ: G
ENERATE
PERFORMING
To evaluate and calculate the catalytic converter efficiency (CE), GPTZ should be run first
for best accuracy of GPT. GPTZ simulates the flow condition of GPT without generating
ozone. This provides accuracy of the NO reading. To initiate GPTZ,
Note
The following table and Figure show the status of the T750's internal pneumatic
components and internal gas flow when the instrument is in GPTZ generating mode.
Table 4-3. Status of Internal Pneumatics During GENERATE GPTZ Mode
MODE
GPTZ
1
Only present if multiple cal gas MFC option is installed.
2
In instruments with multiple MFCs, the CPU selects the MFC to use based on the target gas flow requested.
3
Present with photometer option.
4
Present with O
083730750B DCN8606
Flow output should be set at: (2 + 2 + 2) x 1.5 = 9.000 SLPM
It is not recommended to set any flow rate to <10% or >100%
of the full scale rating of that associated mass flow controller.
WITH MULTIPLE CALIBRATIONS MASS FLOW
CONTROLLERS INSTALLED:
• The full combined flow potential of both mass flow
controllers is available to use with the following limits: 10%
of the lowest rated MFC to 100% of the combined full-scale
ratings for both mass flow controllers.
• The T750 automatically selects the MFC with the lowest flow
rate that can accommodate the requested flow, thereby
affording the most precise flow control.
If no single MFC can accommodate the requested flow rate,
multiple mass flow controllers are used
GPT F
ENERATING
LOW
GPTPS
GPT)
AND
The ozone lamp does not turn on during GPTZ.
VALVES
(X = Closed; O = Open)
(D = Deenergized; E = Energized
CYL
DILUENT
GPT
IN
IN
O
O
E
generator option.
3
C
(
ONDITIONS
TO BE RUN PRIOR TO
O
PHOT
3
CAL1
3, 4
M/R
1
GEN
Reference
E
ON
2
Phase
MFCs
PHOTO
3
PUMP
1
DILUENT
CAL2
ON
2
ON
OFF
91
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Troubleshooting
