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.
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, Johnson Controls 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 in refrigerant circuits can 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 decreases sharply. If a tube
is leaking and water has entered the system, the evaporator and condenser must be valved off
from the rest of the water circuit and drained immediately to prevent severe rusting and corrosion.
The refrigerant system must 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 can be determined as
follows:
1. Remove the heads and listen at each section of tubes for a hissing sound that might indicate
gas leakage. This can help identify the section of tubes that requires further investigated.
- If you can determine the probable location of the leaky tubes, go to Step 2 to treat that
section.
- If the location is not definite, you must investigate all of the tubes.
2. Wash off both tube heads and the ends of all tubes with water.
3. To clear the tubes of traces of refrigerant-laden moisture from the circulation water, blow out
the tubes with nitrogen or dry air.
4. As soon as the tubes are clear, insert a cork into each end of the tube.
5. Pressurize the dry system with 50 psig to 100 psig (345 kPa to 690 kPa) of nitrogen.
6. Repeat Step 3 to Step 5 with all of the other tubes in the suspected section or, if necessary,
with all the tubes in the evaporator or condenser.
7. Keep the cork inserted in the evaporator tubes for 12 h to 24 h before proceeding.
- Depending upon the amount of leakage, the corks may blow from the end of a tube,
indicating the location of the leakage. Go to Step 9.
- If the corks remain inserted, go to Step 8 to conduct a thorough test with the leak
detector.
159
YMC
2
Mod B with OptiView Control Center
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