1. Determine the presence of environmental hazardous gases
CLASSⅠ(Flammable Gases, Vapors or Liquids)
Area Classification
Division 1:
Where ignitable concentrations of flammable gases, vapors or liquids can exist all of the time or some of the time under normal operating conditions.
Division 2:
Where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operating conditions.
Zone 0:
where ignitable concentrations of flammable gases, vapors or liquids are present continuously or for long periods of time under normal operating conditions.
Zone 1:
Where ignitable concentrations of flammable gases, vapors or liquids are likely to exist under normal operating conditions.
Zone2:
where ignitable concentrations of flammable gases, vapors or liquids are not likely to exist under normal operation conditions.
2. Distinguish the types of environmental hazardous gases
Groups
Division 1 and 2 Zone 0, 1 and 2
A(acetylene) IIC (acetylene & hydrogen)
B (hydrogen) IIC (acetylene & hydrogen)
C (ethylene) IIB (ethylene)
D (propane) IIA (propane)
3. Telephone max. surface temperature(less than gas ignition temperature)
Temperature classes
Division 1 and 2: Zone 0, 1 and 2:
T1 (≤450°C) T1 (≤450°C)
T2 (≤300°C) T2 (≤300°C)
T2A (≤280°C) –
T2B (≤260°C) –
T2C (≤230°C) –
T2D (≤215°C) –
T3 (≤200°C) T3 (≤200°C)
T3A (≤180°C) –
T3B (≤165°C) –
T3C (≤160°C) –
T4 (≤135°C) T4 (≤135°C)
T4A (≤120°C) –
T5 (≤100°C) T5 (≤100°C)
T6 (≤85°C) T6 (≤85°C)
4. Equipment protection methods and corresponding marks
| 4.1 International Protection Techniques (Equipment Protection Levels) | 4.2 North American Protection Techniques |
| Zone0:
• Intrinsic safety,”ia”(Ga) • Encapsulation,”ma”(Ga) or “m” for CAN • Class I,Div 1 intrinsic safety |
Div.1:
• Intrinsic safety • Explosionproof • Purged/pressurized (Type X or Y) • Any Class I, Zone 0 technique |
| Zone1:
• Flameproof,”d”(Gb) • Pressurization,”px” or “py”(Gb) or “p” fo4 CAN • Powder filling,”q” (Gb) • Oil immersion,”o” (Gb) • Increased safety,”e”(Gb) • Intrinsic safety,”ib”(Gb) • Encapsulation, “mb” (Gb) or “m” for CAN • Any Zone 0 technique • Any Class I, Div 1 technique |
Div.2:
• Hermetically-sealed • Non-incendive • Non-sparking • Purged / pressurized (Type Z) • Sealed • Any Class I, Division 1 technique • Any Class I, Zone 0,1 or 2 technique |
| Zone2:
• Pressurization,”pz”(Gc) or “n” for CAN • Intrinsic safety,”ic”(Gc) or “n” for CAN • Encapsulated,”nC”(Gc) • Enclosed-break,”nC”(Gc) • Energy-limited,”nL”(Gc) • Hermetically-sealed,”nC”(Gc) • Non-incendive,”nC”(Gc) • Non-sparking,”nA”(Gc) • Restricted breathing,”nR”(Gc) • Sealed,”nC”(Gc) • Encapsulation,”mc”(Gc) or “n” for CAN • Any Zone 0 or 1 technique • Any Class 1, Div 1 or 2 technique |
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5. Determine the presence of dust
CLASⅡ(Combustible Dusts)
Area Classification
Division1:
Where ignitable concentrations of combustible dust can exist all of the time or some of the time under normal operating conditions.
Division 2:
Where ignitable concentrations of combustible dust are not likely to exist under normal operating conditions.
Zone 20:
Where ignitable concentrations of combustible dust or ignitable fibers/flyings are present continuously or for long periods of time under normal operating conditions.
Zone 21:
Where ignitable concentrations of combustible dust or ignitable fibers/flyings are likely to exist under normal operating conditions.
Zone 22:
Where ignitable concentrations of combustible dust or ignitable fibers/flyings are not likely to exist under normal operating conditions.
6. Distinguish the type of dust
Groups
Division 1 and 2: Zone 20, 21 and 22:
E (metal dust – Div. 1 only) IIIC (conductive dust)
F (carbonaceous dust) IIIB (non-conductive dust)
G (non-conductive dust) IIIB (non-conductive dust)
– IIA (combustible flyings)
7. Telephone Max. Surface Temperature
Temperature Classes
Division 1 and 2: Zone 20, 21 and 22:
T1 (≤ 450°C) None.
T2 (≤ 300°C) —————————-
T2A (≤ 280°C) Note: For Zone 20, 21
T2B (≤ 260°C) and 22, equipment
T2C (≤ 230°C) shall be marked to
T2D (≤ 215°C) show the operating
T3 (≤ 200°C) temperature
T3A (≤ 180°C) (maximum surface
T3B (≤ 165°C) temperature)
T3C (≤ 160°C)
T4 (≤ 135°C)
T4A (≤ 120°C)
T5 (≤ 100°C)
T6 (≤ 85°C)
8. Equipment protection methods and corresponding marks
| 8.1 International Protection Techniques (Equipment Protection Levels) | 8.2 North American Protection Techniques |
| Zone 20:
• Enclosure, “ta” (Da) • Intrinsic safety, “ia” (Da) • Encapsulation, “ma” (Da) • Any Class II, Div 1 technique |
Div.1
• Intrinsic safety • Dust-ignitionproof • Pressurized • Any Zone 20 technique |
| Zone21:
• Enclosure, “tb” (Db) or “t” for USA • Pressurization, “p” (Db) • Intrinsic safety, “ib” (Db) • Encapsulation, “mb” (Db) • Any Zone 20 technique • Any Class II, Div 1 technique |
Div.2
• Dust-tight • Hermetically-sealed • Non-incendive • Pressurized • Sealed • Any Class II, Division 1 technique • Any Zone 20, 21 or 22 technique |
| Zone 22:
• Enclosure, “tc” (Dc) • Pressurization, “p” (Dc) • Intrinsic safety, “ic” (Dc) • Encapsulation, “mc” (Dc) • Any Zone 20 or 21 technique • Any Class II, Div 1 or 2 technique |
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Explosion-proof area classification reference
FOR EXAMPLE( Explosion poof telephone certification standard)
| II 2G Ex eb ib [ib Gb] mb IIC T6 Gb
II 2D Ex ib [ib Db] tb IIIC T80 °C Db IP66 |
II: for surface industry
2: Permitted in Zone 1 and Zone 21 G: gas D: dust Ex: Denotes explosion protection eb: Increased safety tb: Enclosure protection ib Gb: Intrinsic safety ib Db: Intrinsic safety mb: Encapsulation ib: Intrinsic safety IIC: acetylene & hydrogen IIIC: conductive dust T6: equipment surface temperature ≤85°C IP66: ingress protection standard |