Johnson Controls YORK YVAM 0350, Руководство по эксплуатации и техническому обслуживанию

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Industries Service Division of the Dow Chemical Company, Tulsa, Oklahoma, with branches in
principal cities is one of the most reliable of these companies.
Evaporator tube leaks
Evaporator 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 can drop off sharply.
If a tube is leaking and water has entered the system, turn off the valve to the evaporator to
separate it from the rest of the water circuit. Immediately drain the evaporator to prevent severe
rusting and corrosion. Drain the refrigerant system and purge with dry nitrogen to prevent severe
rusting and corrosion.
Testing for evaporator tube leaks
About this task:
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 investigation.
- 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.
7. Keep the cork inserted in the evaporator tubes for 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. Go to Step 9.
- If the corks remain inserted, go to Step 8 to conduct a thorough test with the leak
detector.
8. If the corks remain inserted after 12 to 24 hours, two people working at both ends of the
evaporator must carefully test each tube. One person removes the corks at one end of the
tube and the second person removes corks from the opposite end and handles the leak
detector.
a.
Begin with the top row of tubes in the section being investigated and remove the corks
at the ends of one tube simultaneously.
b. Insert the exploring tube for 5 seconds. This is the amount of time required to draw any
refrigerant gas that might have leaked through the tube walls into the detector. A fan
placed at the end of the evaporator opposite the detector can ensure that any leakage
travels through the tube to the detector.
9. Mark any leaking tubes for later identification.
What to do next:
If any of the tube sheet joints are leaking, the leak can be indicated by a leak detector. If a tube
sheet leak is suspected, its exact location can be found by using a soap solution. A continuous
buildup of bubbles around a tube indicates a tube sheet leak.
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