Functional Check Before Starting Work; Automated Switching To Other Measuring Ranges; Exceeding The Lel And Alarm Signal; Button Functions In Measuring Mode - Herth+Buss SelectH2 Bedienhinweis

Operating Instruction

2.5 Functional check before starting work

If the device was kept in highly contami-
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nated impure air for a long time, an under-
ground concentration may be displayed due
to the accumulation of particle deposits on
the sensor. The sensor only becomes clean
gradually after longer periods of use, reach-
ing its original zero point value again.
The sensor head's diffusion area must be
kept clean and free of oil and grease. Spray-
ing with vaporised liquids or gases distorts
the subsequent measurement results.
2.6 Automated switching to other
measuring ranges
Gas concentrations of up to 999 ppm are
shown using this value. If 999 ppm is ex-
ceeded, the volume is shown in vol% as of
1000 pm = 0.1 vol%.
The concentrations are now displayed in in-
tervals of 0.1%. At 1.0 vol%, the analogue bar
reaches the full width of the display.
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2.7 Exceeding the LEL and alarm signal

LEL is displayed if the LEL of the gas is ex-
ceeded. In line with the concentration shown
numerically, the "threshold LEDs" switch to
10, 100, 1000 ppm and 1 vol%. In measuring
mode, the analogue bar functions as an ad-
ditional concentration display and is shown
in full once 1 vol% is reached. The bar dis-
play has a linear resolution range.
An uninterrupted acoustic signal can be
heard. Its speed increases at higher con-
centrations and it becomes a continuous
tone once the LEL threshold is exceeded. If
the LEL is reached when measuring, LEL re-
mains shown in the display, even if the gas
concentration falls again. Resetting this sta-
tus in normal measuring mode is only pos-
sible by switching the device off and restart-
ing it or by pressing the right-hand button
(2x signal tone).
WARNING
If a specific concentration under the
LEL is displayed in a room or contai-
ner, it is still possible that an explosive
gas-air mixture exists at another point
due to light gas rising or heavy gas
"flowing off" .
Operating Instruction

2.8 Button functions in measuring mode

1st function level:
Press the button until a brief signal tone
can be heard. Release the button
2nd function level:
Press and hold the button until 2 short signal
tones can be heard. Release the button.
Upper button:
Switches background lighting for LCD and
buttons on or off. In general, the background
lighting switches on automatically with a
follow-up time of approx. 15 seconds: After
switching the device on and after the heat-
up phase is complete; after each time a func-
tion button is pressed.
The background lighting can be switched
on or off permanently using the upper but-
ton. Two LEDs are provided to illuminate the
LCD. An LED is provided for the keypad.
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Right button:
The right-hand button has
2 sets of functions:
1st function level:
In measuring mode: Switches the signal
tone transmitter on or off in calibration
mode: Confirmation button
2nd function level:
Resets detection mode if the LEL is exceeded
The right button can be used to switch the
signal tone transmitter on or off. The current
status (signal tone transmitter on or off) can
be seen in the display by means of the loud-
speaker special segment. In the 2nd function
level, the detection mode is reset if the LEL
is exceeded. CLr appears in the display for 2
seconds. In calibration mode, the right but-
ton is used to confirm the individual calibra-
tion steps.
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