Detergents and/or some solvents and/or oils may be the cause
of turbidity or cloudiness of a bilge sample. Water-soluble solvents
and detergents do not emulsify in water by themselves, however, they
contribute to the emulsification of oil and insoluble solvents. In
many cases, water insoluble solvents act like oils in that often they
form droplets (though colourless and transparent) that may be read
by both 107(49) and older oil content
meters. Most light scattering 107(49) OCM
are more sensitive to these type of emulsions. The majority of solvents
will not form stable emulsions unless emulsification enhancers are
present as is the case with industrial metal cleaners and other types
of formulated cleaners. Many shipboard detergents and some solvents
used in the engine-room are alkaline and non-volatile and can be easily
detected using a simple test described below. The presence of some
solvents and detergents in the absence of oil, alone and together,
form micro- and mini- emulsions in water. These contaminants, alone
or together, may or may not also cause turbidity, depending on the
exact composition and temperature of the processed bilge water. This
type of non-oil emulsions can be detected by the OCM even when no
visible turbidity exists (visible to the naked eye; visible is a relative
term when instrumentation is involved).