Sierra Monitor Corporation 4501-05 - Manual (Page 5)

Model 4501-XX Toxic Gas Sensor Module
Page 1 of 35
1. PRODUCT DESCRIPTION
1.1 GENERAL
The Model 4501-XX Toxic Gas Sensor Module is a 2-wire transmitter with 4-20 mA output and it offers a broad
array of features including:
• 2-wire loop powered
• 180 day calibration interval
• Selectable ranges (if appropriate for gas type)
• Non-intrusive one-person calibration
• Integral LCD 2-line, 20-character display
• Stainless steel enclosure and sensor housing
• 4-20 mA output
• Long sensor life
• Rotatable faceplate enables multi-directional conduit
installation.
The 4501-XX is designed and approved for installation and
operation in hazardous locations.
Members of the 4501-XX Two-Wire Toxic Gas family include:
▪ 4501-03 Oxygen Gas Sensor Module
▪ 4501-04 Carbon Monoxide Gas Sensor Module
▪ 4501-05 Hydrogen Sulfide Gas Sensor Module
▪ 4501-06 Chlorine Gas Sensor Module
▪ 4501-08 Chlorine Dioxide Gas Sensor Module
▪ 4501-10 Sulfur Dioxide Gas Sensor Module
▪ 4501-12 Nitrogen Dioxide Gas Sensor Module
▪ 4501-25 Ammonia Gas Sensor Module
▪ 4501-26 Hydrogen Fluoride Gas Sensor Module
1.2 MOUNTING CONFIGURATION
Various module mounting configurations can be implemented without special fixtures. Where applicable,
these options are factory configured prior to shipment. Mounting configuration can be selected by the installer
or field technician and are fully described in this manual. Sensor must always be oriented downward.
1.3 THEORY OF OPERATION
Electrochemical sensors are fuel cell-like devices consisting of an anode, cathode, and electrolyte. The
components of the cell are selected so a subject gas, allowed to diffuse into the cell, will cause a chemical
reaction and generate a current. The cells are diffusion limited so the rate the gas enters the cell is solely
dependent on the gas concentration. The current generated is proportional to the rate of consumption of the
subject gas in the cell.