Zone and rating
Zone classification (0 / 1 / 2 for gas, 20 / 21 / 22 for dust) decides the Ex construction and must be formally confirmed by the safety department or design institute.
DIANREZHANELECTRIC HEATINGIndustry Solutions中文INDUSTRY SOLUTION · S6
Ex-area heating,
to the duty.
Heating for flammable or explosive atmospheres: zone, Ex level, temperature class, isolation and over-temperature protection.
- Explosive medium and group
- Hazardous zone classification
- Temperature class requirement
- Medium temperature and flow
- Site electrical conditions
- Certificate requirements
SCENARIO
Typical duty
Read the process, then the equipment
Petrochemical, coating and dust-handling areas contain explosive gas or dust, and the heater itself is a potential ignition source. The design has to satisfy the standard on three levels at once — electrical construction (flameproof, increased safety), surface temperature (temperature class) and protective interlocks. No single item passing means the whole unit is compliant.
Temperature class
Every surface in contact with the medium must stay below the ignition temperature for its class (T1–T6), which directly limits surface load.
Multiple protection
Over-temperature, low flow, earth-leakage, grounding and pressure interlocks must all be provided, and Ex equipment needs its certificate and factory test report.
Installation compliance
Cable entry sealing, cable selection and bonding to ground must follow hazardous-area installation rules — otherwise a perfectly certified unit loses its protection.
SOLUTION PATH
From duty to equipment,
four steps
- 01
Confirm the hazard data
Establish the explosive medium group and ignition temperature, and obtain the zone classification drawing as the basis for Ex rating and temperature class.
- 02
Choose the Ex construction
Select flameproof (Ex d), increased safety (Ex e) or another construction by zone; terminal chambers, terminals and cable glands matched to the same protection.
- 03
Limit surface temperature
Back-calculate permitted surface load from the temperature class, keep a safety margin, and prove the limit under the worst credible case.
- 04
Interlocks and certification
Provide over-temperature cut-out, flow interlock and earth-leakage protection, request the examination certificate and test report, and install to the standard with acceptance checks.
RECOMMENDED EQUIPMENT
Equipment directions
FAQ
Common questions
01What does Ex d IIB T4 actually mean?+
Ex marks explosion-protected electrical equipment, d is flameproof construction, IIB is the gas group, and T4 means the maximum surface temperature stays below 135 °C. The rating must match the site medium and zone — it cannot be downgraded at will.
02Must hazardous-area equipment carry a certificate?+
Yes. Proper Ex electrical equipment is issued an examination certificate and ships with a factory test report. Check certificate details against the nameplate when purchasing.
03How do dust environments differ?+
Dust areas use zones 20 / 21 / 22 and correspondingly Ex t (dust-protected) construction, with particular attention to heat dissipation through dust layers and to cleaning regimes.
INQUIRY PREP
Come prepared,
decide faster on Hazardous Area
Have these parameters ready — they feed directly into model selection, power sizing and mechanical design review.- Explosive medium and group
- Hazardous zone classification
- Temperature class requirement
- Medium temperature and flow
- Site electrical conditions
- Certificate requirements
Other solutions
S1Chemical & process pipeline heatingHeat-up, trace heating and temperature holding for process media. Fix medium, pressure, corrosivity and Ex requirements first.S2Waste gas & VOC treatment heatingWaste-gas pre-heating and duct boosting before catalytic oxidation. Fix air volume, rise, pressure drop and fan interlocks.S3Industrial drying & hot airStable hot air for drying rooms, lines and fresh-air systems. Judge velocity, temperature uniformity and staged control.S4Reactor thermal-oil temperature controlIndirect heating and constant control through a thermal-oil loop. Fix the temperature band, circulation rate and heat consumers.S5Tank & liquid heatingLiquid heat-up through flanged immersion elements or an external loop. Watch level, scaling, material and surface load.