Technical data

7.7.4 Tube Leaks
Cooler 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 will drop off sharply.
If a tube is leaking and water has entered the system,
the cooler 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 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
investigation).
2. Wash off both tube heads and the ends of all tubes
with water.
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. Pressurise the dry system with 3.5 to 6.9 barg
of nitrogen. Repeat this with all of the other tubes in
the suspected section or, if necessary, with all the
tubes in the cooler or condenser. Allow the cooler
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 will be
necessary to make a very thorough test with the
leak detector.
4. After the tubes have been corked for 12 to 24
hours, it is recommended that two men working at
both ends of the cooler carefully test each tube –
one man removing corks at one end and the other
at the opposite end to remove corks and handle the
leak detector. Start with the top row of tubes in the
section being investigated. Remove the corks at
the ends of one tube simultaneously and insert the
exploring tube for 5 seconds – this should be long
enough to draw into the detector any refrigerant
gas that might have leaked through the tube walls.
A fan placed at the end of the cooler opposite the
detector will assure that any leakage will travel
through the tube to the detector.
5. Mark any leaking tubes for later identification.
6. If any of the tube sheet joints are leaking, the leak
should be indicated by the detector. If a tube sheet
leak is suspected, its exact location may be found
by using a soap solution. A continuous buildup of
bubbles around a tube indicates a tube sheet leak.
7.8 Electrical Controls
1. All electrical controls should be inspected for
obvious malfunctions.
2. It is important that the factory settings of controls
(operation and safety) are not changed. If the
settings are changed without York approval, the
warranty will be invalidated.
035L02381-GB0 7-7