Operating instructions

66 IMM AGSB-60
Charging Oil
The oil separator is equipped with two sight glasses
that are used to indicate oil quantity. Oil charge
determination must be done at, or near, full load. It
may be normal to see the oil below the bottom sight
glass while running at part load conditions due to oil
laying in the compressor casting at low refrigerant
flows. However, oil trips at part load indicate low oil
level. While operating at full load with a proper oil
charge in a circuit, the bottom sight glass should
show full with some movement of bubbles, the top
sight glass should appear full but there should be a
violent show of bubbles.
If the separator has too much oil while at full load,
both sight glasses will be clear (level above the upper sight glass) and may exhibit some
bubbling in the top sight glass. If the circuit has too much oil, the circuit may be limited on
low discharge superheat, low suction pressure, high evaporator approach, and/or high
condenser approach due to an excessive amount of oil out in the system. If the oil separator is
low on oil there will be visible levels in one or both sight glasses (this tends to be a collection
of oil in sight glasses as the oil travels down the sides of the vessel during the separation
process). Low oil trips in the Event (1 time trip) and Alarm buffers (2 trips in 60 minutes) may
indicate low oil charge, or operation with low discharge superheat due to over charging oil or
over charging refrigerant.
If it is determined that oil should be added to a circuit, the oil should be pumped in at the
backseat port on the service valve either on the top of the oil separator barrel or at the service
valve on the oil line exiting the oil separator. It may be necessary to shut the circuit off to
reduce the pressure in the oil separator to make it easier to pump oil in to the separator.
Compressor oil must be ICI RL68HP, McQuay Part Number 735030442 in a 1 gallon
container, or ICI RL68H, Part Number 735030444 in a 1 gallon container.
NOTE
Unit operation with low discharge superheat due to excessive oil or excessive
refrigerant charge can cause poor oil separation in the oil separator and the
subsequent coating of heat transfer surfaces, which will reduce unit performance and
limit unit operating range.
Standard Controls
NOTE: A complete explanation of the MicroTech II controller and unit operation is contained in
the Operation Manual OM AGS.
Thermistor sensors
Evaporator leaving water temperature - This sensor is located on the evaporator water
outlet connection and is used for capacity control of the chiller and low water temperature
freeze protection.
Upper
Sight
Glass
Lower
Sight
Glass