INFICON Sensistor ISH2000P Hydrogen Leak Detector, Panel Model - Manual (Page 13)

Hydrogen leak detector Sensistor ISH2000 - Operating Instructions
OP-Sensistor ISH2000-EN-201203 11
EN
Pressure shocks might cause strong sounds which can cause impairment of hearing.
Check that all relevant legislation and safety standards are complied with before
putting Sensistor ISH2000 into service.
4.2 Hydrogen Tracer Gas for leak detection
When pure hydrogen gas is released in air its flammability range spans from 4% to
75% of hydrogen in air. Below 4% there is insufficient chemical energy available for
a flame to occur. Above 75% hydrogen there is not enough oxygen left to support a
flame.
When, for example, a mixture of less than 5.5% hydrogen in nitrogen mixes with air
there is not sufficient energy to support a flame, irrespective of the ratio of air-to-
gas.
When a mixture of more than 5.5% hydrogen in nitrogen is released into air there is
a region of ratios of air-to-gas where the mixture is flammable. When, for example,
a mixture of 10% hydrogen in nitrogen mixes with air there is still very little energy
available. Only in exceptional circumstances can a flame be self-supporting.
However, such mixtures cannot detonate.
4.3 Interferences
Most tracer gas methods suffer from some sort of interference. Either the detector is
sensitive to other gases or vapors, or there are other sources of the gas present to
which the detector is sensitive.
Some examples of possible hydrogen sources:
•
Engine exhaust
• Battery charging stations
• Cigarette smoke
• Breathing air
• Human flatulence
• Scratching on aluminum surfaces
WARNING!
Hydrogen/nitrogen mixtures containing
approximately more than 15% hydrogen can
detonate when mixed in certain proportions
with air.
NOTICE!
Never make your own mixtures. Only use ready-
made mixtures or use a certified hydrogen/
nitrogen mixture mixer installed by your gas
supplier.