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 in. 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 has less
material to dissolve and flush from the tubes with the result that a more satisfactory cleaning job is
accomplished with a probable saving of time.
WARNING
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.
Testing for evaporator and condenser tube leaks
Evaporator and condenser tube leaks 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 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 nitrogen 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 assists 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 require investigations).
2. Wash off both tube heads and the ends of all tubes with water.
Note: 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 psig to 100 psig (345 kPa 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, it is necessary to make a very thorough test with the leak detector.
43Model YK (Style H), R-134a and R-513A
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