Introduction; Applications; Terms And Dimensions - Herth+Buss ELPARTS SelectH2 Operating Instructions Manual

Operating Instruction
1

Introduction

1.1 Applications

The SelectH2 gas detector is a selective and
sensitive hydrogen gas detector. Indication
on the display ranges from 0 ppm up to the
lower explosion limit (LEL) of the gas. The
range is stored in the microprocessor and
can be requested through selective sensors.
The SelectH2 is equipped with a suction
pump, a GGS 1000 and GGS 6000.

1.2 Terms and dimensions

ppm
Stands for parts per million = number of
parts per million other parts, a customary va-
lue for smallest quantities in gas detection.
1 ppm is the quantity of 1cm3 gas in 1m3 of
air. 1ppm = 0.0001 vol%, therefore
0.1% gas = 1000 ppm.
Lower explosion limit LEL
At certain values in a mixture with air, diffe-
rent depending on the type of gas, combusti-
ble gases reach a point at which the influence
of an ignition source results in an explosive
ignition. This is referred to as the lower ex-
plosion limit (or sometimes lower flammable
limit "LFL ") and is 4.0 vol% for hydrogen. This
means that relatively small quantities are
enough to create a flammable mixture. The
following figure shows this using a room as
an example. Gradual filling with gas results
in the value of 4.0% being reached quickly.
The range from 0% gas to the LEL is divided
into % of the LEL. 4.0% hydrogen in air corre-
sponds to 100% of the LEL.
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The SelectH2 uses acoustic signals to indi-
cate that this LEL value is being approached.
LEL: Lower explosion limit
<
UEL: Upper explosion limit
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