Heat Exchanger Maintenance - Trane Cold Generator CICD Series Installation, Operation And Maintenance Manual

Maintenance
Oil Level
While the compressor is running, the oil level may be
below the sight glass but still visible through the sight
glass. The oil level should NEVER be above the sight glass!
Oil Appearance
If the oil is dark and smells burnt, it was overheated
because of compressor operation at extremely high
condensing temperatures, a compressor mechanical
failure, or occurrence of a motor burnout. If the oil is black
and contains metal flakes, a mechanical failure has
occurred. This symptom is often accompanied by a high
amperage draw at the compressor motor.
Notes:
• If a motor burnout is suspected, use an acid test kit to
check the condition of the oil. If a burnout has occurred,
test results will indicate an acid level exceeding 0.05
mg KOH/g.
• The use of commercially available oil additives is not
recommended. Liability for any detrimental effects that
the use of non-approved products may have on
equipment performance or longevity must be
assumed by the equipment owner, equipment service
technician, or the oil additive manufacturer.
Scroll Compressor Functional Test
Since the scroll compressor does not use discharge or
suction valves, it is not necessary to perform a pump-
down capability test, i.e. a test where the liquid line valve
is closed and the compressor is pumped in a vacuum to
see if it will pump-down and hold. In fact, this kind of test
may actually damage the scroll compressor.
NOTICE
Compressor Damage!
Do not pump the scroll compressor into a vacuum.
Scroll compressors can pull internal low vacuums when
the suction side is closed or restricted. This, in turn, can
lead to compressor failure due to internal arcing and
instability in the scroll wraps.
The proper procedure for checking scroll compressor
operation is outlined below:
1. Verify that the compressor is receiving supply power of
the proper voltage.
2. With the compressor running, check suction pressure
and discharge pressure.
Discharge pressure: Take at Schrader fitting provided on
the discharge line. Normal discharge pressures are:
• 90°F to 120°F Condenser LWT: 275 to 430 psig
• 120°F to 140°F Condenser LWT: 430 to 560 psig
Suction pressure: Take at Schrader fitting provided on
the suction line. Normal suction pressures are:
• 42°F to 60°F LWT: 104 to 155 psig
40
• 15°F to 39°F LWT: 60 to 103 psig
Compressor Operational Noises
At low ambient startup: When the compressor starts up
under low ambient conditions, the initial flow rate of the
compressor is low. Under these conditions, it is not
unusual to hear the compressor rattle until the suction
pressure climbs and the flow rate increases. These sounds
are normal and do NOT affect the operation or reliability of
the compressor.
Excessive Amp Draw
Excessive Amp Draw occurs either because the
compressor is operating at an abnormally high
condensing temperature OR because of low voltage at the
compressor motor.
Motor amp draw may also be excessive if the compressor
has internal mechanical damage. In this situation,
vibration and discolored oil can also be observed.
Low Suctions
Continuous low suction pressures are most likely caused
by low evaporator load coupled with a system anomaly
such as low chilled water flow.
Note: Operation of the chiller with saturated suction
temperatures below freezing will cause damage to
the evaporator. If this occurs immediately stop the
machine, diagnose and correct the problem.

Heat Exchanger Maintenance

When to Clean a Brazed Plate Heat
Exchanger (BPHE)
A temperature difference, less than specified, indicates a
sign of scaling because fouling of the channel plate surface
decreases the heat transfer. Hence the inlet and outlet
temperatures of the BPHE should be measured
continuously. Pressure drops larger than specified
indicate scaling since it restricts the channel passage and
thus increases velocity. Make sure that readings follow
water flow rate corresponding to the specification, since
changes in flow rate effect temperatures and pressure
drops. By removing the scale build-ups, the operating
efficiencies of the equipment and heat transfer surfaces
are restored. Other benefits from removing the scale are
that it lowers the pressure drops, reduces the power
consumption and extends the lifetime of the equipment.
How to Clean a Brazed Plate Heat
Exchanger (BPHE)
CICD chiller BPHEs are cleaned quickly and easily with
Cleaning in Place (CIP), a method used for the interior
surfaces of closed systems, such as pipes, vessels, process
equipment, and filters. A chemical fluid is circulated
through the BPHE, without the need for disassembly. The
chemicals dissolve or loosen deposits from process
equipment and piping, giving uniform removal and lower
CG-SVX044B-EN