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Sierra Monitor Corp. 1991 Tarob Court Milpitas, CA 95035 USA (408) 262-6611 (800) 727-4377 Fax: (408) 262-9042
Visit our website: www.sierramonitor.com E-mail: sales@sierramonitor.com
Toxic Gas Sensor Module
2-Wire
Model 4501-XX
The Model 4501-XX Series Toxic Gas 2-wire gas
sensor modules allow easy direct connection to
many DCS, PLC and other control devices. The
sensor module, in a stainless steel enclosure, is
best in class for ease of installation, reliable
operation and ease of use.
The 4501-XX Gas Sensor Module utilizes the electro-
chemical cell to monitor for the specified gas over vari-
ous gas specific ranges. This compact Module requires
minimal maintenance. Internal continuous self-diagnos-
tics will automatically indicate any fault problems. The
4501-XX is best in class providing all the built-in fea-
tures desired by instrumentation and safety profession-
als, including:
• Industry’s longest calibration interval of 180 days
• 2-wire loop powered for easy installation and
direct interface to common PLC and DCS
• Integral scrolling LCD 2-line, 16 character dis-
play
• Non-intrusive one-person calibration
• 316 Stainless Steel or aluminum enclosure
• 4-20 mA output
• Long sensor life
• Robust RFI immunity
• Ability to rotate face plate to enable the enclo-
sure to be mounted in any orientation.
How It Works
Electrochemical sensors are fuel cell-like devices con-
sisting of an anode, cathode, and electrolyte. The com-
ponents of the cell are selected so a subject gas, al-
lowed to diffuse into the cell, will cause a chemical re-
action and generate a current. The cells are diffusion
limited so the rate the gas enters the cell is solely de-
pendent on the gas concentration. The current gener-
ated 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 (toxics).
Explosion proof all models
FM Performance Approval for 4501-05
Model 4501 Series Sensors
4501-04 Carbon Monoxide, CO
4501-05 Hydrogen Sulfide, H
2
S
4501-06 Chlorine, Cl
2
4501-08 Chlorine Dioxide, ClO
2
4501-25 Ammonia, NH
3