Calibration
Equipment Required
Thermo Fisher Scientific
Model 42
i
Trace Level Instruction Manual
4-3
A gas phase titrator (GPT), such as is included in the Thermo Scientific
Model 146 Series Multigas Calibration System is used to generate NO
2
concentrations from NO concentrations. Figure 4-1 shows the suggested
placement of the component parts of a gas phase titration apparatus.
Equipment Damage
All connections between components in the system
should be made with glass, Teflon®, or other non-reactive material.
▲
The airflow controllers should be devices capable of maintaining constant
airflows within ±2% of the required flow rate. The NO flow controller
should be capable of maintaining constant NO flows within ±2% of the
required flow rate.
The pressure regulator for the standard NO cylinder must have a non-
reactive diaphragm and internal parts, and a suitable delivery pressure.
Figure 4–1.
GPT System
The ozone generator must be capable of generating sufficient and stable
levels of ozone for reaction with NO to generate NO
2
concentrations in the
range required.
Gas Phase Titrator
Flow Controllers
Pressure Regulator
Ozone Generator
