Det-Tronics PW9200x Pathwatch IR Gas Detection System - Manual (Page 3)

Section 1
General Information
The installation, operation and maintenance instruc-
tions contained in this manual are for use by qualified
personnel only. All personnel assigned to this equip-
ment should read the instructions provided before ini-
tiating any procedures. The manual should be main-
tained on file so that it is available to installation, oper-
ation and maintenance personnel. To avoid injury to
personnel or damage to the equipment, do not per-
form any procedures other than those described in
this manual unless instructed by the factory or quali-
fied by training.
The information contained in this manual is propri-
etary to Detector Electronics Corporation and is
intended for the sole purpose of installing, operating
and maintaining the PathWatch™ Open Path IR Beam
Detector.
GENERAL DESCRIPTION
The PathWatch™ open path leak detector is an elec-
tro-optical instrument that monitors hydrocarbon
vapors along an open surveillance path. The instru-
ment is designed to operate remotely and to enable
vapor detection in difficult locations. Vapor detection
is based on changes in infrared absorption in the
spectral region of 3 to 4 microns.
The system consists of a transmitter and a receiver,
which can be separated by a distance of 100 meters
or more and are optically aligned. The transmitter
projects an infrared beam through the area under
surveillance to the receiver. In the receiver, the
infrared beam alternately passes through two narrow
band interference filters, a hydrocarbon wavelength
and a reference wavelength. A ratio of the reference
signal to the hydrocarbon signal is computed to pro-
vide an output signal proportional to the total hydro-
carbon content in the beam path. Because it is an
open path system, the instrument’s measurement is a
function of gas concentration (expressed in ppm)
times the length of the surveillance path (expressed in
meters). Thus, the instrument’s output indicates the
average vapor concentration over the entire path
length.
A hydrocarbon alarm relay is activated when the ratio
signal exceeds the adjustable threshold, which corre-
sponds to a selected average vapor concentration in
the path. A separate instrument status alarm relay is
activated when the infrared signal transmission is weak
or blocked, or when an instrument malfunction occurs.
FEATURES
• Active system provides more sensitivity than other
beam detectors.
• Incorporates premium, fundamental-band IR
absorption filters.
• No inherent source of drift.
• Monitors areas from 20 meters to 100 meters long.
• Single pass, straight line approach ensures maxi-
mum beam integrity.
• Single sensor for both active and reference channels.
• Internal fault alarm.
• Dual sensitivity and dual vapor options for different
environments.
• Easy alignment with wide margin for error.
• Capable of “around-the-corner” monitoring.
• Rugged, easy to use pan-tilt mounting bracket.
• Calibrated with real gas.
• Eye safe beam.
• Rugged, explosion-proof construction.
• Cooled IR sensor and air purge port offers potential
for operation in high temperature environments.
• Modular design for easy service.
• Optical surfaces easily protected from the elements.
• CSA certified.
INSTRUCTIONS
PathWatch™ Open Path
IR Beam Detector
PW9200A1 Series
©
Detector Electronics Corporation 2000 9/00 95-8400-01
DET
-
TRONICS ®