3.1.1 Means
are to be provided to maintain the hold space at an acceptable temperature.
This can be achieved by either; the direct removal of the waste heat
from the refrigerant equipment of each container, or by the dissipation
of the waste heat using large quantities of external ambient air.
In each case the system is to be arranged in such a way as to minimise
its affect on the hold space temperature. This may be accomplished
by the use of a ventilation system of a mechanical supply and/or extract
type.
3.1.2 The
selection of a maximum allowable hold temperature is to be agreed
between the designer and Operator/Owner. Whilst the recommendations
given in these Rules do not stipulate a maximum allowable hold temperature,
generally it should not exceed 45°C dry bulb. Guidance should
be sought from container manufacturers on the maximum allowable ambient
air temperature. When determining the maximum allowable hold temperature,
the maximum number of refrigerated containers within the hold space,
operating at their design condition, is to be taken into consideration.
3.1.3 The
ventilation system is to have sufficient capacity to remove or dissipate
the heat from each designated refrigerated container cell and maintain
the hold temperature at or below the maximum allowable hold temperature.
3.1.4 The volume of air to be supplied or exhausted from a hold space per
refrigerated container is at the discretion of the ventilation system designer. For
guidance purposes, an indication of the amount of air required for a standard FEU having
an air cooled condenser operating at the example notation as stated in Pt 7, Ch 10, 1.1 General 1.1.5 is as follows:
- Simple supply only system 90 m3/min
- Supply and exhaust duct system 75 m3/min
- Sealed exhaust system 37 m3/min
3.1.5 The
design of the hold space is to be compatible with the type of ventilation
system proposed. For example, for supply and ducted exhaust systems,
the semi enclosure of each stringer level may be beneficial. For a
simple supply only system the provision of multiple gratings in each
stringer level would benefit the free circulation and removal of warm
air.
3.1.6 Only
container cells served by the ventilation system are to be used for
the transportation of refrigerated containers.
3.1.7 The
design heat rejection for each container cell and the total hold space
heat rejection, including any heat imparted from the ventilation system
fans, if applicable, are to be stated. Guidance on heat rejection
values which may be used is given below.
3.1.8 The
minimum quantity of air supplied or extracted for each container cell
and for each hold space is dependent on the type of system proposed
and to be stated.
3.1.9 The
ventilation system designer is to stipulate the maximum allowable
back pressure occurring within the hold space. Due regard needs to
be given to this value when selecting the ventilation fans and their
ability to operate efficiently again the proposed maximum back pressure.
The lower the back pressure, the more efficient the system and, hence,
the lower the electrical power requirement to drive the fan motors
for a given air throughput.
3.1.10 For
supply air systems, the air outlet at each container location is to
be such as to provide a flow of air towards the container's integral
refrigeration system. Consideration should be given to the use of
movable spigot outlets or ducting to allow both standard and high-cube
containers to be stowed in any location.
3.1.11 The
positions of supply air inlets and exhaust air outlets are to be such
as to reduce the possibility of shortcycling. An adequate distance
is to be maintained between inlet and outlet vents on the open deck.
3.1.12 The
effect of warm exhaust air on deck-stowed refrigerated containers
is to be taken into consideration. Similarly, the effect of warm exhaust
air from deck-stowed refrigerated containers on the inlet air to the
hold is to be considered.
3.1.13 Arrangements
are to be provided to permit a rapid shutdown and effective closure
of the ventilation system in each hold space in case of fire.
3.1.14 Ventilation
ducts which penetrate the deck and/or hatch coaming, including dampers
and / or closures, are to be made of steel and their arrangement is
to be to the satisfaction of the relevant Administration. The use
of nonmetallic flexible ducts, local to each container location, will
be acceptable provided the material demonstrates suitable low flame
spread characteristics.