ICT - ANALYSIS
The Future for Solvent Vapour Degreasing Equipment. Innovation Driven by Legislation Syd Treacher EnviroTech Europe Ltd. – Esher, United Kingdom
V
streacher@hotmail.com
apour degreasing is the simplest
driven the development of new polymers
A little history of the chemistry helps to
but most effective degreasing and
with results as good as, if not better than,
explain the changes since the introduction
cleaning process for industrial
the solvent based originals.
of the vapour degreasing process. Suitable
use. It has, until recently, been subject
As with coatings, cleaning systems have
chemicals must be very good solvents
to little change since it was first invented
had to change. With increased regulation,
for oil, grease, and other industrial soils
in the early part of the last century. The
users of solvent have been targeted
non-flammable, safe for users and the
name for the process is a misnomer, as
and alternatives are encouraged by the
environment and very stable when heated
the cleaning is achieved by solvent vapour
relevant authorities and law makers
continuously for long periods.
condensing on the cooler target parts
often without serious consideration of
Halogenated hydrocarbons are the
the hot liquid solvent dissolving oil and
unintended consequences.
solvents of choice for “Condensation
removing dirt.
For example, water-based cleaning is
Cleaning”. The process is essentially
Vapour degreasing is a mature chemical
the obvious alternative but this has
simple. A tank with a sump to contain
technology on which legislation is now
many disadvantages compared to
the solvent, heaters at the base and
effecting changes so fundamental that
condensation cleaning as although
condensation coils around the top section
the more accurate name for the process
the machines are simple and relatively
to control the height of the vapour is all
“Condensation Cleaning” should be
cheap, the processes require multiple
that is required. When heated in the sump,
used to reflect the way in which it works.
tanks for immersion or spray processing
halogenated solvents produce a saturated
The open topped tanks so ubiquitous
or long programmed cycles in batch
vapour between 3 and 4 times heavier
in factories and workshops worldwide
machines for cleaning, rinsing and drying.
than air at a temperature greater than the
are no longer acceptable and the
Water based processes are slow, energy
ambient conditions. This allows the solvent
alternatives in equipment design and their
intensive and occupy more floor space
vapour to condense on the surface of
fundamental differences in technology,
than condensation cleaning equivalent
the parts to be cleaned. The condensate
which guarantee the continuing use of
where only one tank with small footprint
dissolves the contaminants such as oil,
vapour degreasing in the future, need to
is needed, delivering shorter process
greases and soils returning the used
be considered and understood.
times and most importantly using
solvent into the sump of the machine for
minimal energy.
recycling into vapour which continuously
In Europe, the United States and in other
The ideal cleaning process would be
condenses onto the parts until they have
advanced industrialised economies
“Condensation Cleaning” with water but
achieved the same temperature as the
increasingly stringent legislation to control
due to the physical characteristics of the
solvent vapour when, with no further
emissions of VOCs and especially solvents
water vapour/steam and the inability to
condensation, the process is complete.
has led to new formulations for paints
carry onto the surface of the targeted
Parts removed from the cleaning
and other coatings, where water replaces
parts surfactants to remove the oil,
machines are very clean, warm and dry.
most of the solvent. In the early days the
grease and soils and the difficulty of
The most common halogenated solvents,
quality of the coatings was not as good as
rinsing and especially drying this can only
in use for commercial purposes, are
solvent based coatings but innovation has
ever be a dream.
non-flammable so present no risk in this
118
N. 51 - MAY/JUNE 2018 - international PAINT&COATING magazine
