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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
•
15°F to 39°F LWT: 60 to 103 psig
40
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 overall operating
costs. Following is a general description of the system setup,
the CIP procedure, and the various cleaning fluids.
CG-SVX044F-EN
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