YORK INTERNATIONAL
FORM 160.73-O2 (605)
32
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
rec om mends the use of this type of organization. The
Dow Industries Service Division of the Dow Chemical
Com pa ny, Tulsa, Oklahoma, with branches in principal
cit ies is one of the most reliable of these companies.
TESTING FOR EVAPORATOR AND CONDENSER
TUBE LEAKS
Evaporator and condenser tube leaks in R-134a systems
may result in refrigerant leaking into the wa ter circuit,
or water leaking into the shell depending on the pres-
sure levels. If refrigerant is leaking into the water, it
can be de tect ed at the liquid head vents after a pe ri od
of shut down. If water is leaking into the re frig er ant,
sys tem capacity and effi ciency will drop off sharp ly. 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 im me di ate ly to
pre vent se vere rusting and corrosion. The refrigerant
sys tem should then be drained and purged with dry ni-
tro gen to prevent severe rusting and corrosion. If a tube
leak is in di cat ed, the ex act lo ca tion of the leak may be
de ter mined as fol lows:
1. Remove the heads and listen at each section of tubes
for a hiss ing sound that would indicate gas leakage.
This will assist in locating the section of tubes to be
fur ther in ves ti gat ed. If the prob a ble lo ca tion of the
leaky tubes has been de ter mined, treat that sec tion in
the fol low ing man ner (if the lo ca tion is not defi nite,
all the tubes will re quire in ves ti ga tions).
2. Wash off both tube heads and the ends of all tubes
with water.
Do not use carbon tetrachloride for
this pur pose since its fumes give the
same fl ame dis col or a tion that the
re frig er ant does.
3. With nitrogen or dry air, blow out the tubes to clear
them of traces of re frig er ant laden moisture from the
circulation water. As soon as the tubes are clear, a
cork should be driven into each end of the tube. Pres-
surize the dry system with 50 to 100 PSIG (345 to
690 kPa) of nitrogen. Repeat this with all of the oth er
tubes in the sus pect ed sec tion or, if nec es sary, with
all the tubes in the evaporator or con dens er. Allow
the evaporator or con dens er to re main corked up to
12 to 24 hours be fore pro ceed ing. De pend ing upon
the amount of leak age, the corks may blow from the
end of a tube, indicating the lo ca tion of the leak age.
If not, if will be nec es sary to make a very thor ough
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
op po site end to remove corks and handle the leak
de tec tor. Start with the top row of tubes in the sec-
tion being investigated. Remove the corks at the ends
of one tube simultaneously and insert the ex plor ing
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 evaporator opposite the detector will
as sure that any leakage will travel through the tube
to the detector.
5. Mark any leaking tubes for later identifi cation.
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
bub bles around a tube indicates a tube sheet leak.
Maintenance