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Figure #7 – Detcon IR-642 User Manual

Page 14

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than 30 seconds, the sensor will return to its normal operating condition.

3.6.3 Initial Operational Tests

After a warm up period has been allowed for, the sensor should be checked to verify sensitivity to carbon dioxide

gas.

Material Requirements

*

Detcon PN 6132 Threaded Calibration Adapter

*

Span Gas 50% of full-scale range CO2 in air at a controlled f low rate of 200ml/min.

a)

Attach the calibration adapter to the threaded sensor housing. Apply the test gas at a controlled f low rate of

200 ml/m. Observe that the LCD display increases to a level of 20% of full-scale range or higher.

b)

Remove the test gas and observe that the LCD display decreases to

“0.00 % CO2”.

c)

If alarms are activated during the test, and have been programmed for latching operation, reset them according to

the instructions in section 3.9.2.

Initial operational tests are complete. Detcon CO2 sensors are pre-calibrated prior to shipment and will, in most

cases, not require signif icant adjustment on start up. However, it is recommended that a complete calibration test

and adjustment be performed within 24 hours of installation. Refer to calibration instructions in later text.

3.7 C

ALIBRATION

Material Requirements

*

Detcon PN 3270 MicroSafe™ Programming Magnet

*

Detcon PN 6132 Threaded Calibration Adapter

*

Span Gas containing the applicable calibration gas in air. Span gas concentration is recommended at 50% of

full-scale range (which is the factory default) at a controlled f low rate of 200 ml/min. Other concentrations can

be used as long as they fall within 10% to 90% of range. See section 3.7.2 for details.

3.7.1 Calibration Procedure - Zero

NOTE: Before performing a zero calibration, be sure there is no CO2 gas present.

a)

Enter the calibration menu by holding the programming magnet stationary over “PGM 1” (see figure 7) for 3 sec-

onds until the display reads

“1-ZERO 2-SPAN”, then withdraw the magnet. Note that the “CAL” LED is on.

b)

Next, enter the zero menu by holding the magnet stationary over “PGM 1” for 3 seconds until the display

reads:

“ZERO 0%”, then withdraw the magnet. The sensor has now entered the auto zero mode. When it is

complete the display will read

“ZERO COMPLETE” for 5 seconds and then return to the normal operations

menu,

0.00 % CO2”.

NOTE 1: If the circuitry is unable to adjust the zero to the proper setting the sensor will enter a calibration

Detcon Model IR-640/IR-642 Carbon Dioxide Sensor PG.14

detcon inc.

Program Switch #2

FLT

ALM

1

CAL

MicroSafe™ CO2 Gas Sensor

HOUSTON, TEXAS

PGM

2

PGM

1

ALM

2

MODEL

IR-640

CONTRAST

Alarm & Cal LEDs

Program Switch #1

Menu Driven Display

Plug-in Microprocessor Control Circuit

Display Contrast Adjust

Figure #7

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