Sensor Test And Full Test (Calibration); Sensor Test Countdown; Zeroing The Sensors; Sensor Test - 3M 740 Serie Instrucciones De Uso

Sensor Test and Full Test (Calibration)

The instrument can automatically determine if sensor calibration is required. The sensor test typically takes about 0 seconds. If a sensor calibration is needed this can take
up to  minutes to complete, depending on sensor stability. A sensor calibration can be performed, even if the sensor test interval has not been exceeded and the sensor test
passes, by leaving the gas on the instrument for 0 seconds after the sensor test has passed.
Starting in a non-contaminated environment and with the 70 series detector in normal operating mode, the following steps are required to carry out the sensor test for any
combination of the  sensors – Oxygen (OX), Carbon Monoxide (CO), Hydrogen Sulfide (HS) and combustible gases (EX).
Press and hold the TEST button for  seconds while observing the LCD. Release the button when instructed (Fig. 5).
The LCD will display the number of days since the sensors were last tested and ask if you wish to "ZERO SENSORS?" (Fig. 6). Note that it is not necessary to zero the
sensors prior to bump testing or calibrating, however it is recommended that you do so if you are in a known non-contaminated environment (see SPECIFICATIONS section).
Press the POWER/SELECT button to accept zero calibration. Press the PEAKS/NO button if you wish to bypass a zero setting.
At the conclusion of the zeroing step, the LCD will display "TEST SENSORS?" (Fig. 7). Press the POWER/SELECT button to initiate a sensor test. Press the PEAKS/NO
button to bypass the sensor test.
If you have chosen to do a sensor test place the gas test hood over the sensors and secure firmly with the retaining screw (Fig. 8).
Fig. 5

Sensor Test Countdown

The LCD will display the message "WAITING FOR GAS" and will show the gas concentrations that are expected for EX, CO and HS (Fig. 9). If no gas has been detected in
60 seconds, the sensor test will be aborted and you will need to repeat the above steps.
Attach a hose from the test gas bottle to the gas inlet of the gas test hood, and ensure that the valve is turned on (Fig. 0). A gas flow rate of 0. to 0.5 liters per minute
is required. Once the gas is sensed, the LCD display will change to "TESTING." The sensor test will typically take about 0 seconds if the values are in the expected range.
If the values are outside the expected range, or if the test interval period (see Sensor Test Interval Setting section) has been exceeded the unit will perform a longer "FULL
TEST" (calibration) cycle that can take up to three minutes. A full test (calibration) can also be invoked by leaving the gas applied on the sensors for at least 0 seconds
after the conclusion of the sensor test.
At the conclusion of the sensor test the unit will emit a short beep with a "TEST PASSED" or "FULL TEST PASSED" message on the LCD (Fig. 1). Disconnect the gas and
be sure to turn it off. If the displayed message indicates "SENSOR TEST FAILED," repeat sensor test. Do not use the instrument until the reason for the message has
been determined and corrected. (For help, see TROUBLESHOOTING section of this manual or call M Technical Service at 1-800--60).
Fig. 9

Waiting for Gas

Fig. 6

Zeroing the Sensors

Fig. 0

Sensor Test

Fig. 7
Sensor Test
Fig. 1

Test Successful

1
Fig. 8

Attaching the Gas Test Hood