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text-align: center; text-indent: 0pt; line-height: 16pt;">EPA Precursor Gas Training Workshop

Gas Calibration Systems 

Overview 

Dennis Mikel, EPA Office of Air Quality, Planning and Standards

June 21-22, 2005

EPA Precursor Gas Training Workshop

Outline

Overview
Mass
Flow Controllers (MFC) Calibrators 
Compressed
Gas Cylinders 
Zero
Air Generators
Calculating
the Concentrations
Cautions
Summary

June 21-22, 2005

EPA Precursor Gas Training Workshop

Overview

The combination of the MFC Calibration instruments with NIST traceable
compressed gas cylinders and a clean zero air supply will enable the monitoring organization to create a dynamic calibration
system that can support an NCore
Level II monitoring station.

How do you get such a system? 

I am glad you asked!!

June 21-22, 2005

EPA Precursor Gas Training Workshop

MFC Theory

MFC
technology works on a very simple principle!
Each
MFC has a Thermister (a Thermal Resistor)

Thermisters
are sensitive to heat
As
air passes over it, it loses heat, the more air flow, the more heat
that is lost
This
action changes the resistance of the thermister
The
change in resistance is monitored by a sensitive electronic feedback
loop.  The resistance is converted to voltage and controlled by
computer.

June 21-22, 2005

EPA Precursor Gas Training Workshop

MFC Theory-Calibrator Diagram

Zero Air MFC

June 21-22, 2005

EPA Precursor Gas Training Workshop

MFC Calibrator Features

Thermo (TEI) Model 146   Environics Model 9100

June 21-22, 2005

EPA Precursor Gas Training Workshop

MFC Calibrator Features

Programmable
Scheduled tasks 
Integrated
Switch Closure System