INFORMATION
ON CLEANSING
G AGENTS FOR USE IN MACHINERY SPACES OF SHIPS
(MERC/Circ.289
on 24 November 1994)
The
IMO Guidelines and Specifications for Pollution Prevention Equipment for
Machinery Space Bilges of Ships (resolution MEPC.60(33)) (oil filtering
equipment) have produced some useful and practical information about cleansing
agents and their behaviour.
The
Marino 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.
ANNEX.
INFORMATION OF CLEANSING AGENTS FOR USE IN MACHINERY SPACES OF SHIPS
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 familiarity 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 may 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 pass
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 lime 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 arc
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.
QSDs 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 cure
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 15 ppm bilge alarm.
2.7
Most household types of cleansing agents are emulsifying detergents and should
preferably not be used in machinery spaces: not oven 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.
3.1
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 liters 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.
4.1
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,