Maintenance
The evaporator is large enough to hold all the charge, for any unit, below the centerline of the shell. Therefore, no special precautions are required to restart the unit after isolating the charge in the evaporator.
Filter Replacement
Procedure
A dirty filter is indicated by a temperature gradient across the filter, corresponding to a pressure drop. If the temperature downstream of the filter is 8°F [4.4°C] lower than the upstream temperature, the filter should be replaced. A temperature drop can also indicate that the unit is undercharged. Ensure proper subcooling before taking temperature readings.
1.With the unit off, verify that the EXV is closed. Close the
2.Attach the vacuum hose to the service port on the
3.Evacuate the refrigerant from the
4.Remove the vacuum hose.
5.Depress the Schrader valve to equalize pressure in the liquid line with atmospheric pressure.
6.Remove the bolts that retain the filter flange.
7.Remove the old filter element.
8.Inspect the replacement filter element and lubricate the
CAUTION
Do not use mineral oil. It will contaminate the system.
9.Install the new filter element in the filter housing.
10.Inspect the flange gasket and replace it with a new one if damaged.
11.Install the flange and torque the bolts to
12.Attach the vacuum hose and evacuate the liquid line.
13.Remove the vacuum hose from the liquid line and attach the charging hose.
14.Replace the stored charge in the liquid line.
15.Remove the charging hose.
16.Open the
Lubrication System
The lubrication system has been designed to keep most of the oil lines filled with oil as long as there is a proper oil level in the oil sump.The total oil charge can be removed by draining the oil system, the oil return line from the evaporator, the evaporator, and the compressor. Very small quantities of oil may be found in other components.
Oil Charging Procedure
Proper charging of the oil system is critical to the reliability of the compressor and chiller.Too little oil can cause the compressor to run hot and inefficiently. When taken to an extreme, low oil level may result in infant failure of the compressor.Too much oil will result in high oil- circulation rates, which will foul the condenser and evaporator performance.This will result in inefficient operation of the chiller. Taken to an extreme, high oil levels may result in erratic
•Compressor
•Oil separator
•Discharge line with service valve
•Oil line from separator to compressor
•Oil line drain (lowest point in system)
•Oil cooler
•Oil temperature sensor
•Oil line shutoff valve with flare service connection
•Oil filter (internal to compressor) with
•Oil
•Oil return line from evaporator with shutoff valve, strainer, and solenoid control valve.The standard oil charge for each circuit size is shown inTable 1.
Measuring the oil level
1.To measure the oil level, use the oil drain valve on the oil line and a service valve on the discharge line. This measurement can only be made when the circuit is not running. Note: the bottom plate of the oil separator is approximately 1" [25 mm] thick.
2.The initial oil charge should be approximately at the level as shown inTable 6.This is the approximate oil level if all the oil is in the oil lines, filter, and oil sump, and the unit is in vacuum so that there is no refrigerant dissolved in the oil.
3.After the unit has run for a while, the oil level in the sump can vary greatly.
The
1.Some service procedures may result in loss of small quantities of oil that must be replaced (oil analysis, compressor filter replacement,
2.Additionally, some maintenance procedures may result in virtually all of the oil being removed (compressor motor burn or total removal of the charge to trouble- shoot a unit).
3.Finally, leaks may result in a loss of oil that must be replaced.
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