 |
Home > Parts cleaning > Agents > Hydrocarbons
Aliphatic
hydrocarbon solvents, petroleum hydrocarbon solvents
The aliphatic hydrocarbons may be of straight chain, branched
or cyclic molecular structure. Aliphatic hydrocarbons such as
alkanes, isoparaffins and alkenes are the major components of
gasoline. Many solvents can contain a blend of different aliphatic
types or aliphatic and aromatic hydrocarbons depending on the
end use. Common aliphatic solvents are e.g. mineral spirits,
petroleum naptha, petroleum distillate, cyclohexane, octane,
pentane or isopentane, nonane.
Hydrocarbons may contain traces or larger amounts of aromatic
compounds (check your SDS) and these may cause cancer. However
the alkanes themselves cause nonallergic contact dermatitis,
adverse effects on the central nervous system and fetal problems.
N-hexane has a special neurotoxic effect.
Petroleum hydrocarbons are available in two grades, the basic
petroleum distillates and the specialty grade of synthetic paraffinic
hydrocarbons. Products of the petroleum distillate grade include
mineral spirits, kerosene, white spirits, naphtha. These are
technologically less advanced, as they contain components that
have a broad range of boiling points and may include trace amounts
of benzene derivatives and other aromatics. Petroleum distillates
were available many years before chlorinated solvents attained
their popularity. More recently, improved separation and synthesis
techniques have led to the production of the specialty grade
of paraffinic hydrocarbons. Paraffins are straightchain, branched,
or cyclic alkanes; they are aliphatic as opposed to aromatic
(i.e., derived from benzene and naphthalene). The number of
carbons in the paraffin solvent typically ranges from 10 to
14. Compared to petroleum distillates, the paraffinic hydrocarbons
have very low aromatic content, narrower boiling ranges, and
higher solvency, and they are more expensive.
They are typically used when water contact with the parts is
undesirable. Cleaning with petroleum distillates lends itself
to simple, inexpensive, one-step cleaning in situations where
a high level of cleanliness is not essential. Petroleum hydrocarbons
have high solvencies for many "hard-to-clean" organic soils,
including heavy oil and grease, tar, arid waxes. In addition,
they have low liquid surface tension, which allows them to penetrate
and clean small spaces.
No water is used with hydrocarbon cleaners, so there is no potential
for water corrosion or for water to become trapped in cavities.
Some precision cleaning operations are most effective with hydrocarbon
cleaners. The primary pollution prevention benefits of petroleum
hydrocarbon solvents are that they produce no wastewater and
they are recyclable by distillation. Paraffinic grades have
very low odor and aromatic content and low evaporative loss
rates. However, planned recovery of VOCs is an important part
of pollution prevention if these solvents are to be used.
|
|
|
