Каталог Weidmuller: Electronics - Analogue Signal Conditioning

Technical appendix/Glossary
EX basics
Safety in hazardous areas
Group II "G" divides the Ex zone into three zones with different
safety requirements.
• Zone 0 This zone applies to dangerous explosive atmospheres
where the risk is present often or over long
time periods.
=> > 50 % of the operational time, or more than
1.000 hours per year.
• Zone 1 This zone applies to situation where explosive
atmospheres may occasionally be present during
normal operations.
=> Occasionally, less than 10 hours per year.
• Zone 2 This zone applies to situation where explosive
atmospheres are normally not present or only
briefly present during normal operations.
=> Max. 30 min/year.
Hazardous areas
Zone 0 Zone 1 Zone 2 Safe zone
Explosion risk
Continual,
long-term, often
Occasionally Rarely None
Spark source None Rarely and short-term Occasionally
Continual,
long-term, often
Direct surroundings = Zone 1
≥ 4.0 m²
Piping, Zone 0
0.2 m² 0.2 m²
Manholes
Zone 1
(Zone 0)
Fuel pumps
Zone 1
Zone 2
W
0.8 – 1.0 m²
Tank, Zone 0
When flash point
< 35 °C
Sand filling
Typical division of zones at a fuelling station
W.12