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FORM 160.67-O2
ISSUE DATE: 10/9/2020
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 wa-
ter or chilled water) remove the heads and thorough-
ly 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 con-
necting 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 sav-
ing of time.
Acid cleaning should only be performed by
an expert. Please consult your local water
treatment representative for assistance in
removing scale buildup and preventative
maintenance programs to eliminate future
problems.
COMMERCIAL ACID CLEANING
In many major cities, commercial organizations now
offer a specialized service of acid cleaning evaporators
and condensers. If acid cleaning is required, YORK
recommends the use of this type of organization. The
Dow Industries Service Division of the Dow Chemical
Company, Tulsa, Oklahoma, with branches in principal
cities is one of the most reliable of these companies.
JOHNSON CONTROLS
TESTING FOR EVAPORATOR AND
CONDENSER
Tube Leaks
Evaporator and condenser tube leaks in R-134a sys-
tems may result in refrigerant leaking into the water
circuit, or water leaking into the shell depending on the
pressure levels. If refrigerant is leaking into the water,
it can be detected at the liquid head vents after a period
of shutdown. If water is leaking into the refrigerant,
system capacity and efficiency will drop off sharply. If
a tube is leaking and water has entered the system, the
evaporator and condenser should be valved off from
the rest of the water circuit and drained immediately to
prevent severe rusting and corrosion. The refrigerant
system should then be drained and purged with dry ni-
trogen to prevent severe rusting and corrosion. If a tube
leak is indicated, the exact location of the leak may be
determined as follows:
1. Remove the heads and listen at each section of
tubes for a hissing sound that would indicate gas
leakage. This will assist in locating the section of
tubes to be further investigated. If the probable
location of the leaky tubes has been determined,
treat that section in the following manner (if the
location is not definite, all the tubes will require
investigations).
2. Wash off both tube heads and the ends of all tubes
with water.
Do not use carbon tetrachloride for this
purpose since its fumes give the same
flame discoloration that the refrigerant
does.
3. With nitrogen or dry air, blow out the tubes to
clear them of traces of refrigerant laden moisture
from the circulation water. As soon as the tubes
are clear, a cork should be driven into each end
of the tube. Pressurize the dry system with 50 to
100 PSIG (345 to 690 kPa) of nitrogen. Repeat
this with all of the other tubes in the suspected
section or, if necessary, with all the tubes in the
evaporator or condenser. Allow the evaporator or
condenser to remain corked up to 12 to 24 hours
before proceeding. Depending upon the amount
of leakage, the corks may blow from the end of a
tube, indicating the location of the leakage. If not,
if will be necessary to make a very thorough test
with the leak detector.
SECTION 6 - MAINTENANCE
77
6
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