5.1.1 Installation of mechanical equipment within hazardous areas should be
limited to that considered to be necessary for operational purposes within that
area. Wherever possible, the installation of fired equipment or internal combustion
machinery in hazardous areas should be avoided.
5.1.2 Where it is considered necessary for mechanical equipment or machinery
to be installed in a hazardous area, it is to be constructed and installed so as to
reduce the risk of sparking due to friction between moving parts or the formation of
static electricity, or to ignition due to exposed high-temperature exhausts, etc.
Electrical equipment shall comply with Pt 7, Ch 2, 8 Electrical equipment for use in explosive gas atmospheres.
Non-electrical equipment or machinery shall comply with the appropriate
parts of EN 13463 Series Non-electrical equipment for use in potentially
explosive atmospheres', alternatively protection by installation in a
pressurised enclosure complying with IEC 60079-2 Electrical apparatus for
explosive atmosphere.
Engines (Internal combustion engines) shall normally be located in
non-hazardous (safe) areas. Where it is considered necessary for internal combustion
engines to be located in a Zone 2 hazardous area the engine and installation shall
comply with Pt 7, Ch 2, 7 Engines in hazardous areas of this Chapter. Engines are not permitted
in Zone 0 and Zone 1 hazardous areas on offshore installations.
Where it is considered necessary to install gas turbines in hazardous
areas guidance shall be obtained from relevant International or National Standard(s)
such as ISO 21789 - Gas turbine applications – Safety.
5.1.3 Air compressors are not, in general, to be installed in hazardous areas.
However, where this is not practicable, such installation may be accepted provided
that the air inlet is from a non-hazardous area in accordance with Pt 7, Ch 2, 6.4 Location of air intakes and exhausts, and that the inlet ducting is fitted with
suitable gas detectors arranged to give an audible and visual alarm and to shut down
the compressor in the event of flammable and/or toxic gases entering the air inlet.
Any mechanical equipment or machinery installed in a hazardous area shall comply
with Pt 7, Ch 2, 5.1 General 5.1.2.
5.1.4 Fans located in hazardous areas are to be of the non-sparking type and
comply with EN 14986:2007 Design of fans working in potentially explosive
atmospheres or alternative relevant International or National
Standard.
5.1.6 Wherever possible, piping system arrangements are to preclude direct
communication between hazardous and non-hazardous areas, and between hazardous areas
of different classifications. Where pipes, ducts or cables pass through decks or
bulkheads, the penetration is to be designed to prevent the passage of hazardous
gases.
5.1.7 Maintenance hatches and removable panels are to be provided with
suitable seals to prevent the passage of hazardous gases when closed.
5.1.8 When oil storage pumps and ballast pumps in dangerous or hazardous
spaces are fitted with automatic or remote controls so that under normal operating
conditions they do not require any manual intervention by the operators, they are to
be provided with the alarms and safety arrangements required by Table 2.5.1 Alarm and safety
arrangements, as appropriate.
Alternative arrangements which provide equivalent safeguards will be considered. The
design of the alarm, control and safety systems is to comply with the requirements
of Pt 6, Ch 1, 2 Essential features for control, alarm and safety systems. Where machinery is arranged to start
automatically or from a remote control station, interlocks are to be provided to
prevent start-up under conditions which could cause hazard.
Table 2.5.1 Alarm and safety
arrangements
| Item
|
Alarm
|
Note
|
| Bulkhead gland
temperature
|
High
|
Any machinery item
|
| Bearing temperature
|
High
|
Any machinery item
|
| Pump casing temperature
|
High
|
‘Oil storage’ pumps
only
|
| Bilge level
|
High
|
|
| Hydrocarbon concentration
|
High
|
>20% LEL
|