Figure 4-1. Gpt System; Gas Phase Titrator - Thermo Scientific 42i Instruction Manual

Calibration
Equipment Required

Gas Phase Titrator

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. ▲
Flow Controllers 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.
Pressure Regulator 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
Ozone Generator The ozone generator must be capable of generating sufficient and stable
levels of ozone for reaction with NO to generate NO concentrations in the
2
range required.
Thermo Fisher Scientific Model 42i Trace Level Instruction Manual 4-3