Model NGA2000 HFID

Instruction Manual

748297-E June 2003

SECTION 1

DESCRIPTION AND SPECIFICATIONS

1-1 OVERVIEW

This manual describes the Heated Flame Ionization Detector (HFID) Analyzer Module of Rosemount Analytical's NGA2000 Series of gas analysis components. See Figure 1-1 below and Figure 1-2 on page 3.

The HFID Analyzer Module is designed to continuously determine the concentration of hydrocarbons in a flowing gaseous mixture at

auser-selectable temperature setpoint be- tween 93°C and 204°C (200°F and 400°F). The concentration is expressed in ppm or percent of volume.

The entire HFID Analyzer Module is designed as a stand-alone module, with gas connections made from the rear. All electronics relative to sample detection and conditioning are included in this module.

1-2 TYPICAL APPLICATIONS

The monitoring of atmospheric air for low-level hydrocarbon contaminants and determining the hydrocarbon content of exhaust emissions

+90V

Sample

from internal combustion engines are examples of typical applications for the HFID Analyzer Module.

1-3 THEORY OF TECHNOLOGY

This Analyzer Module uses the flame ioniza- tion method of detection. The sensor is a burner in which a regulated flow of sample gas passes through a flame sustained by regulated flows of a fuel gas (a hydro- gen/diluent mixture) and air.

Within the flame, the hydrocarbon components of the sample stream undergo a complex ionization that produces electrons and positive ions. Polarized electrodes collect these ions, causing current to flow through an electronic measuring circuit.

The ionization current is proportional to the rate at which carbon atoms enter the burner, and is therefore a measure of the concentration of hydrocarbons in the sample. This measure of concentration is placed on the network, where it can be shown on a data acquisition device.

Negative Ion

Collection Plate

Signal Conditioning

Positive

Carbon

Ions

Air

Fuel

Figure 1-1. Flame Ionization Detection Technology

Rosemount Analytical Inc. A Division of Emerson Process Management

Description and Specifications

1-1