Detcon CX-DM - Manual (Page 5)

Model CX-DM
1. Introduction
1.1 Description
Detcon
ꞌs CX-DM sensor for toxic gas and O
2
deficiency are non-intrusive sensors designed to detect and
monitor a wide range of toxic gases in air. Detection ranges for toxic gases are 0-1ppm up to 0-10,000ppm
(typical ranges of detection are 0-10ppm, 0-25ppm, 0-50ppm and 0-100ppm). Ranges for O
2
deficiency are 0-
1% up to 0-25% by volume. The basic sensor assembly consists of an electrochemical sensor mounted in an
intrinsically safe stainless steel housing and includes a Splash Guard Cal Adapter.
Electrochemical Sensor Technology
The toxic gas sensors are based on electrochemical cells. Each cell consists of three electrodes embedded in an
electrolyte solution and housed beneath a diffusion membrane. Sensitivity to target gases is achieved by
varying composition of any combination of the sensor components. The cells are diffusion limited by way of
small capillary barriers resulting in a long service life of three or more years. The electrochemical cell is
packaged as a field replaceable plug-in sensor.
Figure 1 Construction of Electrochemical Toxic Sensor
Principle of Operation
The O
2
deficiency sensor technology is a two electrode galvanic metal air battery type cell housed as a field
replaceable intelligent plug-in sensor. The cell is diffusion limited and functions as a direct current generator
proportional to the amount of oxygen adsorption. The sensors are temperature compensated and show good
accuracy and stability over the operating temperature range of -20°C to 50°C (-4°F to +122°F). The sensor is
warranted for two years with an expected service life of up to 2.5 years in ambient air at 20.9% oxygen.
Figure 2 Construction of Galvanic Cell
CX-DM Instruction Manual Rev. 1.3 Page 1 of 40