6-12T -296
tact occurs. Do not allow the solution to
splash onto concrete.
5. Fill the tubes with this solution by filling from the bot-
tom. See Figure 6-17. Important: be sure to provide
a vent at the top for escaping gas.
Centrifugal pump
30 GPM at 35’ head
Pump
Suction
Pump
support
Tank
Fine mesh
screen
Return
Remove water
regulating valve
Condenser
Globe
valves
Vent
Close vent pipe
valve when pump
is running.
Priming
connection
Figure 6-17 Water-Cooled Condenser Cleaning --
Forced Circulation
6 Allow the Oakite No. 32 solution to soak in the tube
coils for several hours, periodically pump-circulating
it with an acid-proof pump.
An alternate method may be used whereby a pail
(see Figure 6-18) filled with the solution and
attached to the coils by a hose can serve the same
purpose by filling and draining. The solution must
contactthescaleateverypointforthoroughde-scal-
ing. Air pockets in the solution should be avoided by
regularly opening the vent to release gas. Keep
flames away from the vent gases.
7 The time required for de-scalingwill vary, depending
upon the extent of the deposits. One way to deter-
mine when de-scaling has been completed is to
titrate the solution periodically, using titrating equip-
ment provided free by the Oakite Technical Service
representative. As scale is being dissolved, titrate
readings will indicate that the Oakite No. 32solution
is losing strength. When the reading remains
constant for a reasonable time, this is an indication
that scale has been dissolved.
8 When de-scaling is complete, drain the solution and
flush thoroughly with water.
9 Following the water flush, circulate a 56.7 gram (2
ounce) per 3.785 liter (1 U.S. gallon) solution of
Oakite No. 22 thru the tubes to neutralize. Drain this
solution.
10 Flush the tubes thoroughly with fresh water.
NOTE
If thecondenser coolingwaterisnot beingused
as drinking water or is not re-circulated in a
closedor tower system, neutralizingis not nec-
essary.
11 Put the unit back in service and operate under nor-
malload. Checktheheadpressure. Ifnormal, athor-
ough de-scaling has been achieved.
What You Can Do For Further Help:
Contact theEngineering and ServiceDepartment of the
OAKITEPRODUCTSCO.,19RectorStreet, NewYork,
NY 10006 U.S.A. for the name and address of the
service representative in your area.
Fill condenser with clean-
ing solution. Do not add
solution more rapidly than
vent can exhaust gases
caused by chemical
action.
Condenser
Vent
pipe
1” Pipe
5’ Approximate
3’ to 4’
Figure 6-18 Water Cooled Condenser Cleaning -
Gravity Circulation
6.13 FILTER-DRIER
On unitsequipped witha water-cooledcondenser, if the
sight glass appears to be flashing or bubbles are
constantly moving through the sight glass when the
suctionmodulationvalveisfullyopen, theunitmayhave
a low refrigerant charge or the filter-drier could be
partially plugged.
a. To Check Filter-Drier
1. Test for a restricted or plugged filter-drier by feeling
the liquid lineinlet andoutlet connections of thedrier
cartridge. If the outlet side feels cooler than the inlet
side, then the filter-drier should be changed.
2. Check the moisture-liquid indicator if the indicator
shows a high level of moisture, the filter-drier should
be replaced.
b. To Replace Filter-Drier
1. Pump down the unit (refer to paragraph 6.4 and
replace filter-drier.
2. Evacuate the lowside inaccordance withparagraph
6.6.
3. After unit is in operation, inspect for moisture in sys-
tem and check charge.
6.14 THERMOSTATIC EXPANSION VALVE
The thermal expansion valve (see Figure 2-2) is an
automatic device which maintains constant superheat
oftherefrigerant gas leavingthe evaporator,regardless
of suction pressure.
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