Spectrex Quasar 900 Open-Path Gas Detection System - Manual (Page 16)

SafEye TM Quasar 900 Gas Detector
4 Applications
2.2 Applications
The Quasar 900 system may be used to monitor flammable gas
concentration in various applications, such as:
 Petrochemical, pharmaceutical and other chemical storage and
production areas.
 Flammable and toxic chemical storage sites and hazardous waste
disposal areas.
 Refineries, oil platforms, pipelines, refueling stations and fuel storage
facilities.
 Hazardous loading docks, transportation depots and shipping
warehouses
 Engine rooms
 Compressor and pumping stations
 Test cells
 LNG-LPG Systems
 Offshore Floating Production Storage and Shipping vessels (FPSO), and
fixed oil rigs.
2.3 Principle of Operation
The Quasar system detects gases through a dual spectral range monitoring,
analyzing the absorption of radiation caused by gases in the atmosphere
and comparing it (ratio) to background atmospheric absorption.
2.3.1 Definitions of Terms
The following list defines gas concentrations measurement terms that are
used in this manual:
Table 1: Gas Concentrations Measurement Terms
Term Description
LEL Lower Explosive Limit: The minimum concentration of a
substance (gas/vapor) in air mixture that can be ignited.
This mixture is different for every gas/vapor, measured in
% of LEL.
LEL.m Integral of Concentration in LEL units (1 LEL = 100% LEL)
and the operation distance in meters (m).
2.3.2 Spectral Finger Print
Each hazardous material is detected at a specific wavelength selected
according to its specific spectral absorption or "finger print". The detection
process involves two separate filters, one transmitting radiation that is
absorbed by a particular gas and one that is not sensitive to it.