Ludlum Measurements 239605, Manual

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Model 3-IS & 3-IS-1 Technical Manual
Section 1
Ludlum Measurements, Inc. Page 1-1 October 2010
Introduction
he Model 3-IS and 3-IS-1 are portable intrinsically safe radiation
survey instruments that are designed to be intrinsically safe in Class
1 Division 1, Group A, B, C, and D hazardous conditions. They
have four linear ranges used in combination with exposure rate,
count rate (cpm- counts per minute) or a combination of both exposure rate
and count rate (referred to as “combo”) meter face dials. The instruments
feature a regulated high-voltage power supply, unimorph speaker with audio
ON
-
OFF
capability, fast-slow meter response, meter reset button and a six-
position switch for selecting battery check or scale multiples of ×0.1, ×1,
×10 and ×100. Each range multiplier has its own calibration potentiometer.
The unit body and meter housing are made of cast aluminum and the can is
0.090” thick aluminum.
The audio provides a brief “click” for every radiation event detected. It also
provides a steady tone to warn the user of a low battery condition. This low
battery warning overrides the position of the
AUD ON
-
OFF
switch.
There are three Geiger-Mueller (GM) detectors which are qualified for use
with the Model 3-IS. Additionally, two types of scintillation detector may be
used. The qualified GM detectors operate at 900 volts. Operating voltage
for the scintillation detectors is determined by using the plateau method
outlined on page 6-4, or by using a detector-specific procedure.
The Model 3-IS-1 features an internal energy-compensated GM detector,
and thus has no connector or cable for external detectors. This internal
detector provides for easy, one-handed operation and provides
measurement of gamma radiation up to 1000 mR/hr (1 R/hr).
The unit is operated with two ˝
D
˝ cell batteries (Duracell Procell PC1300
1.5V Alkaline).
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1
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