The IMO Guidelines and Specifications for Pollution Prevention Equipment for
Machinery Space Bilges of Ships (resolution MEPC.60 (331)) (oil filtering equipment) have
produced some useful and practical information about cleansing agents and their behaviour.
The Marine Environment Protection Committee (MEPC) considered these findings and
concluded that the effective operation of oil separating and filtering equipment could be
improved if this information is brought to the attention of shipowners and shipboard
personnel.
Therefore, the Committee decided to issue an MEPC circular
The Committee encourages Member Slates of IMO to make this circular available to
shipowners and shipboard personnel.
Annex Information of cleansing Agents for use in Machinery Spaces of Ships
1 Operational procedures
1.1 Research and reports from Administrations have revealed that failure of oil filtering
equipment to perform effectively is mainly caused by improper use of cleansing
agents and unfamiliarity with proper operation of the oil filtering equipment,
especially when cleansing agents, heavy fuel oil and lubricating oil form part of the
oily water bilge mixture to be filtered.
1.2 Shipowners and ship operators should ensure that an operation manual is on board,
and that the crew members are given an opportunity to study this manual and
practice with the equipment to become fully conversant with it.
1.3 It is essential for the proper use of the equipment that crew members have a good
understanding of both its working principles and its operation.
1.4 Administrations nay require crew members responsible for the oil filtering equipment
to demonstrate their ability and knowledge of its operation.
1.5 The oil filtering equipment will perform best while processing bilge water with a
low level of oil content. Reducing the oil content of bilge water not only improves
the effectiveness of oil filtering equipment but also improves economy and reduces
fire hazards.
1.6 There are a number of ways to reduce the amount of oil which finds its way into
the bilge:
- leaking oil pipes. couplings, etc . should be repaired without delay;
- water from oil tanks should be drained into a waste oil tank;
- waste oil from cleaning or other activities should be drained into a waste oil tank;
- machinery which is likely to leak oil should be fitted with drip trays which can be
drained to a waste oil tank; and
- cleaning of floor plates, engines, etc , with oil products should be minimized.
1.7 It is important that machinery spaces be kept clean. The use of cleansing agents is
one of the primary means of achieving this, and it is realized that most cleansing
agents eventually end up in the bilge
1.8 However, many of the cleaning products cause oily-water mixtures to emulsify.
Unfortunately, these emulsions have an adverse effect on the performance of oil
filtering equipment.
1.9 Emulsions should be broken or separated before the mixture is pumped into the
filtering equipment. It should also be realized that after separation the emulsion may
reform when the mixture is stirred, for instance by a centrifugal type pump that may
be used to pump the bilge water to the oil filtering equipment.
1.10 To avoid problems caused by emulsions, use the cleansing agents which are
recommended by the manufacturer of the oil filtering equipment or which pasts the
emulsion separation test described in section 3.
1.11 Different cleansing agents are used for different cleaning purposes. It is important to
read the label or product data sheet prior to selecting a cleansing agent appropriate
for the job. Where label information is inadequate to determine the effects on the
cleansing agent of the oil filtering equipment, the emulsion separation test in section
3 should be conducted before allowing the cleansing agent to drain into the bilge.
1.12 Care should be taken to avoid draining different types of cleansing agents into the
bilge at the same time. Otherwise, emulsions may be formed which may even be
permanent.
2 Properties of cleaning products
2.1 Some cleansing agents already on the market claim not to effect oil filtering
equipment . They either do not produce an emulsion, or they have the ability to
break the emulsion a short time after it is formed; these products are called
Quick-Separating Detergents (QSDs).
2.2 There are many different types of cleansing agents . The two principal types are
QSDs and emulsifying detergents.
2.3 QSDs work by penetrating between the surface and the adhering grease and oil, and
after using, any emulsion formed by the cleaning action is quickly broken QSDa
should generally be used for cleaning machinery spaces.
2.4 Other kinds of cleansing agents are emulsifying detergents. The grease and oil is
broken up into fine droplets which form an emulsion that can be quite stable. As
most hand wash lotions or gels belong to this type, special care should be taken
when using these products.
2.5 When a QSD is mixed with only a small amount of emulsifying detergent, as for
instance a hand cleaner. small water droplets will be formed and these are likely to
be taken up by the oil. This may well result in a stable mixture looking like a
mayonnaise, which will effectively block the oil filtering equipment.
2.6 Furthermore, caution should be taken when using hydrocarbon solvent-based QSDs
since they may affect the performance of the 15ppm bilge alarm.
2.7 Most household types of cleansing agents are emulsifying detergents and should
preferably not be used in machinery spaces: not even in the smallest quantities.
However, if this is unavoidable, arrangements should be made to prevent the effluent
from draining into the bilge; for example, hand wash basins in machinery spaces
should have a permanent drain connection to a dirty water tank.
2.8 Emulsifying detergents should not be allowed to drain into the bilge or machinery
spaces.
3 Emulsion separation test
3.1 A simple method to check if the separation time of an emulsion is acceptable can be
carried out as follows:
- fill two bottles of approximately 0.5 litres in size about 60% full of clean fresh
water,
- add approximately 10% of oil, preferably fuel oil to both bottles,
- to one bottle only add 2%, or an amount specified by the cleansing agent
manufacturer, of the cleansing agent to be tested,
- shake both bottles well by hand for approximately one minute,
- let both bottles stand,
- the bottle without cleansing agent should show clear water underneath the oil
within a relatively short time,
- the other bottle will need more time for separation; the time needed for this bottle
is the so-called separation time which should be less than one hour. At the end of
the separation time the mixture of this bottle should have water with light turbidity
at least over half of the height of the bottle.
3.2 The purpose of the bottle with only water and oil is to see if the oil will separate
from the water: if this should not be the case, the test is invalid because the effect
of the cleansing agent cannot be determined.
4 Safety aspects
4.1 When applying cleansing agents it should always be kept in mind that they might
contain certain chemicals which are hazardous to human health and may cause acute
or chronic intoxication. In addition, some cleansing agents are flammable liquids
although in general the flash point is rather high. Therefore, it is important to follow
the manufacturers instructions for its storage, application and precautions to be
taken.
4.2 Some Administrations have issued special safety regulations or guidelines with respect
to the composition and use of cleansing agents. These requirements may deal with
the storage of cleansing agents, marking of receptacles, provision of data sheets,
operating instructions and special personal protection equipment and should be
carefully observed.
4.3 For safely reasons cleansing agents used on board should:
- have a flash point above 61°C; and
- not contain Benzene, Tetrachloromethane, Tetrachloroethane,
Pentachloroethane or chemicals with a comparable toxicity.
4.4 When applying cleansing agents, contact with skin and respiration of vapours should
be minimized. If possible work should be done at well-ventilated places. Never leave
receptacles open at the work place. Extensive cleaning may require the use of
filter-type respiratory protection.
4.5 Before starting work, eyes should always be protected by chloroprene goggles. In
addition, barrier creams against skin defatting effects should be used and gloves and
protective clothing be worn.
4.6 It is recommended not to use high pressure spray equipment to apply cleansing agents