Generate>Gptz, Gptps, Gpt: Understanding Gas Phase Titration (Gpt); Determining The Diluent Gas Flow Rate With O Generator Option; Meeting Usepa Guidelines For Gpt Calibration - Teledyne T750 User Manual

Determining the Diluent Gas Flow Rate with O
If the O generator is installed and in use, Equation 4-2 will be slightly different, as shown
3
in Equation 4-3 since the O
WHERE:
EXAMPLE:
Note
G
ENERATE
(GPT)
Gas phase titration (GPT) provides an alternative method to UV photometry for ozone
analysis. This section first describes the principles of GPT, then provides the information
necessary for performing GPT Zero (GPTZ), GPT Preset (GPTPS), and GPT with the O
Generator and Photometer option.
Note

Meeting USEPA Guidelines for GPT Calibration

The USEPA has published guidelines for the pneumatic parameters involving GPT
calibrations. These guidelines are meant to ensure that the O
that the risk of producing other un-wanted reactions is minimized. These guidelines are
published in the U.S. 40 CFR pt. 50, appendix F. In this appendix are requirements for the
Residence Time in the reaction volume as well as a Dynamic Parameter specification.
For the purposes of calculating these parameters, the volume of the GPT reaction chamber
is 130 cc.
083730750B DCN8606
flow is a constant value, typically 105 cm
3
=
DIL Totalflow
flow
DIL = required diluent gas flow
flow
Totalflow = total gas flow requirements of the system.
O = the flow rate set for the O
3 flow
(typically about 0.105 SLPM)
• If the total flow requirement of the system is 9.000 SLPM,
• The source gas flow rate is set at 0.105 SLPM.
• The required source gas flow rate would be:
DIL = 9.0 SLPM – 0.105 SLPM
flow
DIL = 8.895 SLPM
flow
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 MUL-
TIPLE CALIBRATIONS MASS FLOW CONTROLLERS INSTALLED:
The combined flow potential of both mass flow controllers is
available 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 will automatically select 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.
>GPTZ, GPTPS, GPT: U
It is strongly recommended that GPTZ and GPTPS be
performed prior to running GPT.
Generator Option
3
-
O
3
flow
generator; a constant value
3
G P
NDERSTANDING AS HASE
/NO reaction is complete, and
3
3 /min.
Equation 4-3
T
ITRATION
3
89