Testing For Evaporator And Condenser Tube Leaks - York YVWA Installation Operation & Maintenance

FORM 201.30-ICOM1 (519)
ISSUE DATE: 05/22/2019
2. To make sure that the concentration of refriger-
ant reached all parts of the system, slightly open
the oil charging valve and test for the presence of
refrigerant with a leak detector.
3. Test around each joint and factory weld carefully
and thoroughly.
4. To check for refrigerant leaks in the evaporator
and condenser, open the vents in the evaporator
and condenser heads and test for the presence of
refrigerant. If no refrigerant is present, the tubes
and tube sheets may be considered tight. If refrig-
erant is detected at the vents, remove the heads,
locate the leak, (using the soap test or leak detec-
tor) and repair.
5. When system is absolutely tight, blow the nitro-
gen and refrigerant mixture through the charging
valve.
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 into the shell, depending on the pressure
levels.
If refrigerant is leaking into the water, it can be detect-
ed 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, determine the exact location of the
leak using the following information:
1. Remove the heads and listen at each section of
the tubes for a hissing sound that would indicate
gas leakage, which will help locate the section of
the tubes to be further investigated. If the prob-
able location of the leaky tubes has been deter-
mined, treat that section in the following manner
(if the location is not definite, investigate all of
the tubes).
JOHNSON CONTROLS
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
process 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.
4. After the tubes have been corked for 12 to 24
hours, it is recommended that two men working
at both ends of the evaporator 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 five seconds –
this should be long enough to draw into the de-
tector any refrigerant gas that might have leaked
through the tube walls. A fan placed at the end of
the evaporator 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.
SECTION 7 - MAINTENANCE
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