Sierra Monitor Corporation 5000 Cover Plate - Toxic Gas Module, messages, SERVICE Page

SMC sierra monitor corporation Sentry Instruction Manual - Version 6

7.9 TOXIC GAS SENSOR MODULE

7.9.1 DESCRIPTION

Toxic Gas Sensor Modules include the following models and default ranges:

5100-06 Chlorine -10 PPM

5100-07 Hydrogen - 2000 PPM

5100-12 Nitrogen Dioxide - 20 PPM

5100-13 Carbon Monoxide, High Range -

1,000 PPM

5100-10 Sulfur Dioxide - 100 PPM

5100-16 Carbon Monoxide, H2 Tolerant -

2,000 PPM

5100-19 Nitric Oxide - 20 PPM

5100-21 Hydrogen Chloride - 20 PPM

5100-22 Hydrogen Cyanide - 20 PPM

5100-27 Ethylene Oxide - 20 PPM

The Toxic Sensor Module includes a sensor assembly and electronic assembly installed in an explosion proof housing.

The sensor assembly includes a reuseable housing
		Figure 7-11
and disposable electrochemical sensor.	The
		Cover Plate - Toxic Gas Module
assembly screws into one hub of the sensor
module enclosure and plugs into the bottom
electronics card via a six pin connector.		7.9.3 ADJUSTMENT PROCEDURE
Cabling from the controller connects to a three pin spring		Prior to reading voltages and making adjustments perform
loaded terminal strip on the electronics assembly.		a visual inspection to confirm that there are no physical

7.9.2 TROUBLE ANALYSIS	problems such as water in the electronics enclosure,
	wiring damage or corrosion.
Electrical adjustment, or replacement of the sensor will be
	Use Figure 7-11 to locate test points during the following
necessary under the following conditions:
	procedures.

•Controller displays the following error

messages 7.9.3.1 SIGNAL ADJUSTMENT

SENSOR FAILURE

LOW SENSITIVITY

•False readings or alarms are received due to sensor inaccuracy.

Warning: During sensor adjustments the concentration reading on the controller will be inaccurate and alarm level concentrations may be displayed. If false activation of the alarm relays will cause a problem disconnect the relay wiring prior to adjustment or turn the module off using the "Change Module" mode.

NOTE

Although all the necessary data can be collected with a voltmeter at the sensor module, some helpful information can be displayed on the controller or printed. See diagnostic codes 0004 and 0008 in Appendix C.

It is unlikely that any electrical adjustment will be required except when a new sensor is installed.

To make the electrical adjustment connect a voltmeter to SIGNAL OUT (pos) and GND (ground) and use SPAN ADJ potentiometer to adjust the voltage based on the following:

•1% of full scale = 0.02 VDC.

•100% of full scale = 2.00 VDC.

7.9.3.2SENSOR REPLACEMENT

The toxic gas sensor should be replaced when it can no longer be calibrated correctly. Generally this is every twenty four to thirty months.

SERVICE Page: 78