Model 4501-XX Toxic Gas Sensor Module
1. PRODUCT DESCRIPTION
1.1GENERAL
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
•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 installation attitudes.
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:
▪4501-04 Carbon Monoxide Gas Sensor Module
▪4501-05 Hydrogen Sulfide Gas Sensor Module
▪4501-06 Chlorine Gas Sensor Module
1.2MOUNTING 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.
1.3THEORY 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.
Sierra Monitor electrochemical sensors provide improved reliability by allowing the gas to diffuse into the sensor through a capillary port, rather than diffusing through membranes. The result is an extremely stable sensor with very low temperature and pressure coefficients and the capability to monitor gas as ppm.
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