The document outlines the classification of hazardous areas according to DS/EN 60079-10-1 and related guidelines, focusing on the presence of flammable gas atmospheres and the necessary equipment selection under ATEX regulations. It delineates various zones of hazardous areas based on the likelihood of gas presence and details the grading of release types to inform safety practices in offshore and industrial settings. Additionally, it provides definitions for sources of release, ventilation degrees, and specific equipment classification relevant to such environments.

1. HAZARDOUS AREA
HAZARDOUS AREA
CLASSIFICATION
DS/EN 60079-10-1 & UK
ENERGY INSTITUTE, IP15
ENERGY INSTITUTE, IP15

2. BACKGROUND – DS/EN 60079-10-1
CLASSIFICATION EXPLOSIVE GAS ATMOSPHERES
CLASSIFICATION – EXPLOSIVE GAS ATMOSPHERES
ATEX 1999/92 EC Di ti / B h l di ti 92/91/EC ( ff h )
• ATEX 1999/92 EC Directive / Borehole directive 92/91/EC (offshore)
• Danish Regulations (BEK 1480 + Guideline to that)
• Norway: PSA Facilities Regulation (Guideline) points towards IEC
61872-7 – which points towards IEC/EN 60079-10-1-
• Allow for correct selection of equipment (ATEX 94/9/EC)
• Allow for correct selection of equipment (ATEX 94/9/EC)
• Classify for flammable gasses, vapours and mists
• Flammability: Dependent on flash point and design/service
temperature
Probability for fire/explosion:
P(Release) x P(Ignition)

3. AREA CLASSIFICATION – ZONING
EN 60079-10-1 / IP 15
Zone 0: The part of a hazardous area in which a
flammable atmosphere is continuously present or
present for long periods
Zone 1: That part of a hazardous area in which a
flammable atmosphere is likely to occur in normal
operation
operation
Zone 2: That part of a hazardous area in which a
flammable atmosphere is not likely to occur in normal
p y
operation, and if it occurs, it will only exist for a short
period
Non-hazardous: areas that do not fall into any of
the above (IS NOT ‘SAFE AREA’)
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6. Definitions – EN 60079-10-1
• Source of Release: A point of location from which a gas, vapour,
mist or liquid may be released into the atmosphere so that an
explosive gas atmosphere could be formed.
• Grades of release: There are three basic grades of release, as
listed in order of decreasing frequency and likelihood of the
listed in order of decreasing frequency and likelihood of the
explosive gas atmosphere being present:
• Continous grade
• Primary Grade
• Secondary Grade
y
• Degree of ventilation (natural / artificial):
• High ventilation (VH)
High ventilation (VH)
• Medium ventilation (VM)
• Low ventilation (VL)
Low ventilation (VL)

7. HAZARDOUS AREA CLASSIFICATION –
GRADE OF RELEASE – IP 15 DEFINITIONS
C d l l h l
Continuous grade release: A release that is continuous or nearly so, or
that occurs frequently and for short periods
If it is likely to be present for more than 1000 hours per year.
Primary grade release: a release that is likely to occur periodically or
occasionally in normal operations, i.e. a release which, in operating
y p p y
procedures is anticipated to occur
If it is likely to be present for between 10 to 1000 hours per year.
Secondary grade release: A release that is unlikely to occur in
normal operation and, in any event, will do so only infrequently and
for short periods i e a release which in operating procedures is not
for short periods i.e. a release which in operating procedures is not
anticipated to occur. Such release may be of unknown size e.g.
fracture of a drain or unknown size e.g. corrosion hole.
If it is likely to be present for 1 to 10 hours per year
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If it is likely to be present for 1 to 10 hours per year.

8. ZONE – VENTILATION – GRADE OF RELEASE
8

9. Hazardous Area Classification Data Sheets
Part I: Flammable Material List and data

10. Hazardous Area Classification Data Sheets
Part II: List of sources of release

11. Hazardous Area Classification Drawings
EN 60079-10-1, SEC 7.2

12. WHY COMBINE EN 60079-10-1 WITH IP15
• For continous & primary grades of release, the leak size is
typically known.
• We need some advise regarding size and types of leak sources for
secondary grade of release – EN 60079-10-1 is very open on the
subject
subject.
R f t EN 60079 10 1 1 S
• Ref. to EN 60079-10-1, 1. Scope:
For detailed recommendations regarding the extent of the
hazardous areas in specific industries or applications, reference
may be made to national or industry codes relating to those
applications.

13. HAZARDOUS AREA CLASSIFICATION – IP 15
 Risk Target is 10-5 year
For most offshore plants, where there is control of ignition sources
outside the hazardous areas, IP 15’s LEVEL I is applied
Does not concern major releases (spread of flamables more
than 30 m). These shall be minimised by design and operation
to an acceptable residual risk
to an acceptable residual risk.
IP 15, sec. 5.4.5.1: “As a guide, when there are more than 10 leak
sources within close proximity (i e Where their notional zone 2 would
sources within close proximity (i.e. Where their notional zone 2 would
overlap), the area should be classified as zone 2”
Classification only required for fluids with flashpoints nearer than 10
Classification only required for fluids with flashpoints nearer than 10
deg. C to the handling/ambient temperature in the area.
Following: Open field, naturally ventilated, wind speed 0.5 – 2.0 m/s
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g p , y , p /

14. POINT SOURCE
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15. FLUID CATEGORY / CLASS
Fluid
Category
Description
A A flammable liquid that, on release, would vaporise rapidly and
substantially.
B A flammable liquid, not in Category A, but at a temperature
sufficient for boiling to occur on release.
C A flammable liquid, not in Categories A or B, but which can, on
release, be at a temperature above its flash point, or form a
release, be at a temperature above its flash point, or form a
flammable mist or spray.
G(i) A typical methane-rich natural gas.
G(ii) Refinery hydrogen.
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16. FLUID CATEGORY - EXAMPLES
Fluid Category
g y
Condensate / LPG: A
Crude / unstabilized: B
Crude / stabilized: C
Wet/dry gas: G(i)
Produced Water: C
Produced Water: C
Diesel: C
Helifuel: C
Hydraulic oil: C
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17. RELATIONSHIP – CLASS & CATEGORY
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18. IP 15 PROCEDURE – SECONDARY GRADE
RELEASE
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19. IP 15 – LEVEL I, II & III – FLANGES & VALVES
For offshore oil/gas installations, where there is a strong control of
ignition sources outside the classified area LEVEL I is typically
ignition sources outside the classified area, LEVEL I is typically
selected.
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20. CLASSIFICATION AT SPECIFIC EQUIPMENT
Fig 1A. Pump mounted on plated deck – high integrity pump (typically double mechanical seals)
HOLE
DIA
FLUID
CAT.
PRESSURE
BARG
RADIUS
R1 R2
DIA CAT. BARG R1 R2
2 B 10<P<50 4000 5000
2 B P<10 4000 4000
2 C 10<P<50 4500 5500
2 C P<10 4500 4500
Refer to appendix 5 John Crane recommendations for mechanical
Refer to appendix 5, John Crane recommendations for mechanical
seals.
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21. CLASSIFICATION AT SPECIFIC EQUIPMENT
Fig. 1B, Pump mounted on grated deck – high integrity pump (typically double mechanical seals)
HOLE FLUID PRESSURE RADIUS
DIA CAT. BARG R1 R2
2 B P<50 4000 N/A
2 C P<50 4500 N/A
Refer to appendix 5 John Crane recommendations for mechanical
Refer to appendix 5, John Crane recommendations for mechanical
seals.
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22. CLASSIFICATION AT SPECIFIC EQUIPMENT
Fig. 2A, Flange/valve installed over grated deck
g , g / g
HOLE
DIA
FLUID
CAT.
PRESSURE
BARG
RADIUS
R1 R2
1 A / C P<50 2500 N/A
1 B P<50 2000 N/A
1 G(i) P<100 1100 N/A
1 G(i) P<100 1100 N/A
1 G(i) 100<P<150 1400 N/A
1 G(i) 150<P<200 1600 N/A
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23. CLASSIFICATION AT SPECIFIC EQUIPMENT
Control valves, often used block valves and valves not well maintained: A zone 1
with R = 0.3 m.
with R 0.3 m.
A specific evaluation shall be made to decide if there is a further zone 2 around the
zone 1.
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24. CLASSIFICATION AT SPECIFIC EQUIPMENT
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25. CLASSIFICATION AT SPECIFIC EQUIPMENT
SPO Compact Flange
Fully welded ASME B31 3 piping
Fully welded ASME B31.3 piping
and SPO compact flanges
No classification!
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26. CLASSIFICATION AT SPECIFIC EQUIPMENT
EN 1127-1, ANNEX B
Defines equipment which are ”durably technically tight”,
• Canned motor pumps
examples:
• Magnetic coupled sealless pumps
• Tongue/groove flanges (EN 1092-1, Type C & D)
o gu /g oo a g ( 09 , yp & )
• If rarely detached: NPT connections (up to DN 50)
Should normally not cause classified areas.
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27. CLASSIFICATION AT SPECIFIC EQUIPMENT
Seal Sealing Arrangement Description
Max. Release Flow Rate
(kg/s)
Hazard Radius R1/R2
(m)
John Crane recommendations for mechanical seal Maximum release flow
rates for pumps in all fluid categories and process pressures
ITA / Appendix 5:
John Crane
Single
Single seal ( without fixed throttle
bushing, in a pump with no wear
rings). This may be a component or
cartridge, general-purpose seal
Use IP-15 calculation ( Hole
size. 0,23xshaft dia.)*
See IP-15
Single
Single seal with a fixed throttle
bushing or a single seal in an API
610 pump. This may be a
component or cartridge, general-
l
0,0003 <2
John Crane
recommendaations for
Pumps / Mechanical Seals.
purpose seal
Single
Single seal,, supplied to ISO 21049,
with a fixed throttle bushing ( code
1CW-FX) or a single seal, supplied
to ISO 21049 with a solid floating
bushing ( code 1CW-FL) in an API
610 or ISO 13709 pump.
0,00015 <2
Dual, unpressurised seal ( without
fixed throttle bushing in a pump with
(
For dry gas seals on
J h C Dual unpress.
fixed throttle bushing, in a pump with
no wear rings). This may be a
cartridge or non-cartridge, general-
purpose seal
Use IP-15 calculation ( Hole
size 2 mm )**
See IP-15 ( 4 to 6 )
Dual unpress.
Dual, unpressurised seal ( ISO
21049, code 2CW-CW, 2CW-CS,
with auxiliary plan 52, 75 or 76 ) with
a fixed throttle bushing or the same
seal arrangement but in an API 610
0,00001 <2
compresors, John Crane
states the two last rows
for pumps will apply for
th d l pump or ISO 13709 pump.
Dual unpress.
Dual, unpressurised seal as above
but containement system connected
to an open vent pipe
0,00001 at seal. 0,0025 at vent <2
Dual press
Dual pressurised seal (without fixed
throttle bushing, innon-cartridge,
general purpose seal
Use IP-15 calculation ( Hole
size 2 mm )**
See IP-15 ( 4 to 6)
Dual, pressurised Seal (ISO 21049,
code 3CW-CW with auxiliary plan
the dry gas seals,
depending on execution of
the dry gas seal
Dual press
code 3CW-CW, with auxiliary plan
53 or 54 ) with a fixed throttle
bushing or the same seal
arrangement but in a API 610 or ISO
13709 pump
NIL _
Dual press
Dual, pressurised Seal (ISO 21049,
code 3NC, with auxiliary plan 74 )
with a fixed throttle bushing or the
same seal arrangement but in a API
0,01 2***
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610 or ISO 13709 pump
* Use seal chamber presssure as release pressure ( If not known use discharge pressure )
** Use 5 bara as release pressure
*** For R2, Cat C use 2,5 m

28. HAZARDOUS AREA DOSSIER
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29. ENCLOSED AREAS
• Minimum 12 ACH (IP 15), no stagnant zones to ensure area
classification will correspond to grade of release.
• Pressurisation to safe a room adjacent to classified area: Min. 5
mm WG overpressure (IP 15)
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