070.650-IOM (JUL 19)
Page 38
SGC/SGX ROTARY SCREW COMPRESSOR
MAINTENANCE
VIBRATION ANALYSIS
Periodic vibration analysis can be useful in detecting bearing
wear and other mechanical failures. If vibration analysis is
used as a part of your preventive maintenance program, take
the following guidelines into consideration.
1. Always take vibration readings from exactly the same
places and at exactly the same percentage of load.
2. Use vibration readings taken from the new unit at start-up
as the baseline reference.
3. Evaluate vibration readings carefully as the instrument
range and function used can vary. Findings can be easily
misinterpreted.
4.Vibrationreadingscanbeinuencedbyotherequipment
operating in the vicinity or connected to the same piping
as the unit.
OIL QUALITY AND ANALYSIS
High quality and suitable oil is necessary to ensure compres-
sor longevity and reliability. Oil quality rapidly deteriorates in
systems containing moisture and air or other contaminants. In
order to ensure the quality of the oil in the compressor unit:
1. Only use FRICK oil or high quality oils approved by Johnson
Controls - FRICK for your application.
2.OnlyuseFRICKlterelements.Substitutionsmustbeap-
proved in writing by Johnson Controls - FRICK engineering
or warranty claim may be denied.
3. Participate in a regular, periodic oil analysis program to
maintain oil and system integrity.
OPERATING LOG
The use of an operating log as included in this manual
permits thorough analysis of the operation of a system by
those responsible for its maintenance and servicing. Con-
tinual recording of gauge pressures, temperatures, and other
pertinent information, enables the observer and serviceman
to be constantly familiar with the operation of the system
and to recognize immediately any deviations from normal
operating conditions. It is recommended that readings be
taken at least daily.
TROUBLESHOOTING GUIDE
Successful problem solving requires an organized approach to
denetheproblem,identifythecause,andmaketheproper
correction. Sometimes it is possible that two relatively obvi-
ous problems combine to provide a set of symptoms that
can mislead the troubleshooter. Be aware of this possibility
and avoid solving the wrong problem.
ABNORMAL OPERATION ANALYSIS AND CORRECTION
Four logical steps are required to analyze an operational
problem effectively and make the necessary corrections:
1.Denetheproblemanditslimits.
2. Identify all possible causes.
3. Test each cause until the source of the problem is found.
4. Make the necessary corrections.
Therststepineffectiveproblemsolvingistodenethe
limits of the problem. The following list of abnormal system
conditions can cause abnormal operation of SGC/SGX
compressors:
1. Insufcientorexcessiverefrigerant or gas load.
2. Excessively high suction pressure.
3. Excessively high discharge pressure.
4. Excessively high or low temperature coolant to the oil
cooler.
5. Excessive liquid entering the compressor (slugging).
6. Insufcientoilcooling.
7. Excessive oil cooling
8. Incorrect gas line sizing.
9. Improper system piping.
10. Wrong operation of hydraulic operated slide valve.
11. Problems in electrical service to compressor.
12. Moisture present in the system.
Make a list of all deviations from normal compressor opera-
tion. Delete any items, which do not relate to the symptom
and separately list those items that might relate to the symp-
tom. Use the list as a guide to further investigate the problem.
The second step in problem solving is to decide which items
on the list are possible causes and which items are addi-
tional symptoms. High discharge temperature and high oil
temperature readings on a display may both be symptoms
of a problem and not causally related.
The third step is to identify the most likely cause and take
action to correct the problem. If the symptoms are not re-
lieved, move on to the next item on the list and repeat the
procedureuntilyouhaveidentiedthecauseoftheproblem.
Oncethecausehasbeenidentiedandconrmedmakethe
necessary corrections.
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