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Newsletter winter 1997 |
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Multiple Stage Cleaning Reduces New Solvent
Purchases & Saves Money
Let your dirty solvent
do your dirty work. That's the
principle behind multiple-stage cleaning. Whether you are
cleaning printing presses or automotive parts, multiple-stage
cleaning can reduce your costs for solvent purchases and disposal.
When one container of solvent is used for
cleaning, the solvent becomes dirty with the soils that it
removes from the parts, decreasing its ability to clean well.
With multiple-stage cleaning, dirty solvent removes most of
the soil, while the clean solvent of the additional stages
thoroughly cleans the parts and brings them to specification.
Solvent use decreases because the solvent
is used longer before it is discarded. When only given
a cursory look, multiple-stage cleaning appears to use more
solvent. Not so. While you need extra containers of solvent
for the added cleaning steps, all the solvent lasts much longer
than it would if used in a single cleaning step.
Using multiple-stage cleaning can also making
drying times more consistent. After the dirty cleaning of
the first stage, the cleaner solvent in the later stages evaporates
at a consistent rate.
Determine the number of stages that work
best for your operation. Often only two or three stages
are appropriate. Multiple-stage cleaning can be accomplished
with flushing, immersion, sprays or a combination of these.
The first stage can be used as a presoak.
| A three-stage cleaning
process works like this: |
| Stage 1: |
Majority of the soil is
removed using dirty solvent. |
| Stage 2: |
Soil, left after the first
stage, is removed using partially dirty solvent. |
| Stage 3: |
Any remaining soil is removed
by the cleanest solvent. |
Industry Example
When the solvent in the stage-1 container becomes too dirty,
empty it. Refill the container with the solvent from the subsequent
stage; for example, the solvent from stage 2 becomes stage-1
solvent. Refill stage 3 with fresh solvent.
Anagram, a flexographic printer, used one
bucket of solvent to flush unused ink from the printing decks.
With the help of a MnTAP intern, they developed a three-stage
cleaning process for their printing presses.
Using all three stages takes them an extra
four to six minutes per deck. Often using only their first
two stages is sufficient.
Savings: $28,200 per year through reduced
solvent purchases and disposal costs. Reduces solvent waste
by almost 120 drums per year.
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