Technical data

7.7.2 Tube Cleaning
Cooler
It is difficult to determine by any particular test whether
possible lack of performance of the water cooler is due
to fouled tubes alone or due to a combination of
troubles. Trouble which may be due to fouled tubes is
indicated when, over a period of time, the cooling
capacity decreases and the split (temperature
difference between water leaving the cooler and the
refrigerant temperature in the cooler) increases. A
gradual drop-off in cooling capacity can also be caused
by a gradual leak of refrigerant from the system or by a
combination of fouled tubes and shortage of refrigerant
charge. An excessive quantity of oil in the cooler can
also contribute to erratic performance.
Condenser
Condenser trouble due to fouled tubes is usually
indicated by a steady rise in head pressure, over a
period of time, accompanied by a steady rise in
condensing temperature, and noisy operation. These
symptoms may also be due to foul gas build-up. Purging
will remove the foul gas revealing the effect of fouling.
Tube Fouling
Fouling of the tubes can be due to deposits of two types
as follows:
1. Rust or sludge - which finds its way into the tubes
and accumulates there. This material usually does
not build up on the inner tube surfaces as scale, but
does interfere with the heat transfer. Rust or sludge
can generally be removed from the tubes by a
thorough brushing process.
2. Scale - due to mineral deposits. These deposits,
even though very thin and scarcely detectable
upon physical inspection, are highly resistant to
heat transfer. They can be removed most
effectively by circulating an acid solution through
the tubes.
7.7.3 Tube Cleaning Procedures
Brush Cleaning of Tubes
If the tube consists of dirt and sludge, it can usually be
removed by means of the brushing process. Drain the
water sides of the circuit to be cleaned (cooling water or
chilled water) remove the heads and thoroughly clean
each tube with a soft bristle bronze or nylon brush. DO
NOT USE A STEEL BRISTLE BRUSH. A steel brush
may damage the tubes.
Improved results can be obtained by admitting water
into the tube during the cleaning process. This can be
done by mounting the brush on a suitable length of 1/8"
pipe with a few small holes at the brush end and
connecting the other end by means of a hose to the
water supply.
The tubes should always be brush cleaned
before acid cleaning.
Acid Cleaning of Tubes
If the tubes are fouled with a hard scale deposit, they
may require acid cleaning. It is important that before
acid cleaning, the tubes be cleaned by the brushing
process described above. If the relatively loose foreign
material is removed before the acid cleaning, the acid
solution will have less material to dissolve and flush from
the tubes with the result that a more satisfactory
cleaning job will be accomplished with a probable
saving of time.
Acid cleaning should only be performed by an expert.
Please consult your local water treatment
representative for assistance in removing scale build-up
and preventative maintenance programs to eliminate
future problems.
7-6 035L02381-GB0