2. Engineering specifications
2.1.1 The system should consist of a control
panel housing the gas analysis unit and sample extraction
pump(s), connected to gas sampling pipes, and one or more
2.1.2 The system should be capable of
continuously measuring hydrocarbon gas concentrations, and may
be arranged to operate on a sequential scanning principle,
provided that each sampling line of each protected space is
analysed at intervals not exceeding 30 min.
2.1.3 The system should be provided with a means
to monitor air flow acceptable to the Administration.
2.1.4 Means should be provided to prevent
ballast water from entering the system.
2.1.5 The system should have ingress protection
suitable for the installed location of each component. In any
event, the system should be designed such that dust may not
enter in sufficient quantity to interfere with the satisfactory
operation of the equipment and water splashing against the
enclosure from any direction has no harmful effect.
2.1.6 Enclosures containing electrical
components such as gas analysis units, extraction pumps, and
alarm control devices should be of gas-tight construction having
doors fitted with gaskets. Electrical components which would
reasonably be expected to come into contact with sample gases
should be explosion-proof.
2.1.7 The system should be designed, constructed
and installed to prevent the leakage of hydrocarbon gases into
any accommodation and service spaces, control stations or
2.1.8 The system should be designed to withstand
supply voltage variations and transients, ambient temperature
changes, vibration, humidity, shock, impact, and corrosion
normally encountered on ships, and to avoid the possibility of
ignition of a flammable gas mixture.
2.1.9 The switchover sequence should be designed
to keep changing the sampling line of each protected space
according to a planned sequence, even if flammable gas above the
alarm level is detected at a sampling point.
2.2 Component requirements
2.2.1 The gas analysis unit should be:
- designed and tested according to standard IEC 60079-29-1, or
alternative standards acceptable to the Administration;
- capable of accurately measuring gas concentrations between
0% and 200% of the alarm setpoint defined by paragraph
- designed to prevent tampering or unauthorized interference
with the alarm setpoint.
2.2.2 Extraction pumps
220.127.116.11 Extraction pumps should have sufficient
power and be of adequate capacity to operate with the normal
conditions of ventilation in the protected spaces with the
connected sampling pipe sizes to ensure a response time in
accordance with paragraph
2.1.2 for all sampling points.
18.104.22.168 Main and back-up extraction pumps of
equal power and capacity should be provided and arranged to
automatically switch over to the back-up pump in case of failure
of the main pump. Alternatively, any failure of the main
extraction pump should be automatically indicated and at least
one spare extraction pump or equivalent parts should be provided
2.2.3 Sampling pipes
22.214.171.124 Sampling pipes should be constructed of
stainless steel, or other corrosion resistant materials
acceptable to the Administration, and should be a minimum of 6
mm in inner diameter.
126.96.36.199 The location, number and arrangement of
sampling points within a space should be determined in
consideration of design parameters including the configuration
of the space, internal obstructions, the length and internal
diameter of sampling pipes, the extraction pump capacity, and
the density of the vapours of the oil products intended to be
188.8.131.52 Sampling pipes located within ballast
tanks should be of sufficient strength to withstand hydrostatic
pressure when in the most severe ballast condition.
184.108.40.206 Sampling pipes should be arranged to
prevent progressive flooding upon failure.
220.127.116.11 Sampling pipes should be provided with a
suitable connection for the fitting of portable detection
18.104.22.168 Sampling pipes should include a means to
prevent blockage from debris accumulation.
22.214.171.124 Sampling pipes should be