Sierra Monitor Corporation 201, 203, 20X, 206 User Manual

Model 20X Series

Gas Sensor Monitors

Model 201 - Combustible Gas

Model 203 - Hydrogen Sulfide

Model 206 - Carbon Monoxide

The Model 20X Series are all-weather, solid-state, fixed-installation singlealarm monitors designed for continuous area monitoring of Combustible Gas, Hydrogen Sulfide or Carbon Monoxide.

The Model 20X Series consists of 3 gas sensor modules, Model 201 for Combustible Gas, Model 203 for Hydrogen Sulfide and Model 206 for Carbon Monoxide. The monitors provide 0.5 Amp dry contract relay that is activated when the concentration of gas exceeds the factory-set (and user-adjustable) level. A TTL signal can be user configurable to interface with Sierra Monitor's alarm panels. This signal may be used to activate a

remote alarm, fan or process controller.
The standard configuration has a normally operating open
relay but a fail-safe normally operating closed relay is
field selectable. A durable, cast aluminum explosion-
proof enclosure houses the sensor electronics. The en-
closure provides sealing for hazardous areas - Class I,
Division 1, Groups C, D. The sensor with porous metal
cover is assembled in an aluminum housing that screws
directly into the electronics enclosure. The cover both
protects the sensor and acts as a flame-arrestor. The	Remote Alarm Available
monitor can be installed up to 500 feet from the power
source.	If a remote alarm is desired (required for 20X-00), the
	Model 2102 Dual Channel Alarm Panel can be connected
Semiconductor-Type Sensor	up to 500 feet away from the monitors.
A solid-state semiconductor-type sensor and associated	Model 201 - Combustible Gas
electronic circuitry ensure trouble-free, long-term opera-
tion. There are no pumps, filters, or chemical cells to	The Model 201 can detect a wide range of combustibles.
replace or maintain. Except periodic calibration to verify	Typical applications include combustible gas monitor-
the alarm setting, no attention is required after installa-	ing in manholes, tanks, natural gas fields, parking ga-
tion. The user may adjust the alarm level by using cali-	rages and vehicle maintenance facilities, sewage treat-
bration gas with concentration equal to the alarm level.	ment plants, laboratories, chemical plants, and more.
Features	Benefits

nExplosion-proof enclosure

nNo chemical cells to replace, no periodic maintenance required other than routine calibration

Can operate continuously in work areas where hazardous gases could be present

Maintenance free operation

n All the electronic circuitry needed to operate	Quick easy installation and connection to alarm
panel the monitor contained in a compact unit

Sierra Monitor Corporation 1991 Tarob Court Milpitas, California 95035 [phone] [phone] Fax: [phone]