Lcd Contrast; Alarms And Warnings; Gas Alarms; Low Battery Alarm - 3M 740 Serie Instrucciones De Uso

LCD Contrast

To change the LCD Contrast (background lighter or darker), press and hold the PEAKS/NO button for approximately 7 seconds. The LCD Contrast will be displayed. To
change the LCD Contrast from its current setting, press the arrows until the desired level of contrast is reached. To exit, either wait 7 seconds for it to return to normal
operating mode or press the POWER/SELECT button.

ALARMS AND WARNINGS

Do not cover or obstruct display, audible alarm opening or visual alarm cover. Doing so may adversely affect product performance and result in sickness or death.
Vibrator and LCD may not function effectively below – ºF (–0 ºC). Using the instrument below this temperature may adversely affect product performance and result
in sickness or death.
Do not open the 70 series detector in a potentially hazardous area. Failure to do so may result in sickness or death.
High off-scale combustible readings (indicated by 'OVR') indicate an explosive concentration and may result in sickness or death.
Leave the area immediately if the instrument displays any rapidly increasing readings followed by declining or erratic readings may indicate a gas concentration beyond
the upper scale limit (e.g. 100% LEL) which may be hazardous. Failure to do so may result in sickness or death.
The 70 series detector will activate warning and alarm signals whenever targeted gas concentrations reach an alarm or warning set point for the unit. Alarm conditions
are indicated by the sounding of the buzzer once every second, actuation of the vibrator and flashing of the red LEDs. The LCD display will begin flashing the level of gas
and which sensor is in alarm. If the sensor is in STEL or TWA alarm, this will also be noted on the LCD display, if this alarm is enabled (see Viewing and Changing Settings).
Flashing of the red LEDs only indicates a warning condition.

Gas Alarm

EX (Combustible)
CO (Carbon Monoxide)
CO – STEL Alarm
CO – TWA Alarm
HS (Hydrogen Sulfide)
H S – STEL Alarm

HS – TWA Alarm
OX (Oxygen) – High
OX – Low
Table 1 – Default Alarm Set Points (All set points are user adjustable)

Gas Alarms

The Gas Alarms are activated whenever the targeted gas concentration exceeds the alarm set point (Fig. 1). These levels are also user configurable on start up (see Viewing
and Changing Settings). Factory default alarm levels are listed in Table 1. The STEL alarm uses a 15-minute floating average gas reading. The STEL is used to set short-term
exposure limits. The TWA alarm uses an 8-hour floating average gas reading. The TWA is used to set daily exposure limits. The audible and vibratory alarms can be silenced
for up to 5 minutes (Fig. ). This can be done by pressing the POWER/SELECT button. The visual alarm will continue until concentrations fall below the alarm set points.

Low Battery Alarm

If the battery is approaching the point where it cannot provide power to continue monitoring, a Low Battery Alarm will occur (Fig. ). When this alarm occurs, the unit
should be taken to a safe location and the battery changed or charged according to these User Instructions. The LCD display should be checked frequently to see if there
are flashing readings indicating a gas alarm in addition to the low battery alarm. The low battery alarm will continue for at least 15 minutes or until the detector is turned off.
This alarm cannot be silenced.
Fig. 1
Gas Alarm

Gas Warnings

The Gas Warning is activated when the target gas concentration starts to approach the alarm set point. The Gas Warning starts at 50% of the target gas alarm set point, or
for Oxygen, 50% of the difference between atmospheric and high or low alarm levels. The warning is indicated by a periodic flash of the red LED indicator.
WARNING
Factory Default Alarm Set Points
10% LEL
5 ppm
00 ppm
5 ppm
10 ppm
15 ppm
10 ppm
.0 % v/v
19.5 % v/v
Fig. 

Low Battery Alarm

STEL Alarm
11
Fig.