This SOP for Preventive Maintenance of Chiller is to establish a standardized procedure for conducting preventive maintenance on the chiller system, ensuring its optimal performance, energy efficiency, and prolonging its operational life.
To lay down the Procedure for preventive maintenance of chiller installed in technical area.
SCOPE:
This SOP is applicable to preventive maintenance of chillers installed in technical area .
RESPONSIBILITY:
Technician/ Operator shall be responsible for proper execution of preventive maintenance as per SOP of Preventive Maintenance of Chiller.
Engineering – Head shall be responsible for reviewing the SOP and for ensuring proper execution of Preventive Maintenance of Chiller as per SOP.
ACCOUNTABILITY:
Engineering – Head shall be accountable for proper implementation of the SOP for Preventive Maintenance of Chiller.
DEFINITIONS:
Planned and scheduled maintenance activities performed on a chiller system to prevent potential issues, ensure efficient operation, and extend the operational life of the equipment.
PROCEDURE:
Preventive maintenance shall be executed as per the SOP No.: SOP/EN/XXXYYY – Execution of Preventive Maintenance of Chiller.
Ensure that the spare parts are available at the time of Preventive Maintenance of Chiller.
Preventive Maintenance of Chiller– Mechanical
Clean all water strainers in chilled water and condensing water piping system
Shut down the pumps
Close the isolation valve of pump.
Drain out the strainer by drain plug provided at the bottom.
Open the flanges of strainer, remove the mesh; clean and replace if required.
Put the mesh inside the strainer, tight the nut and bolts of flanges.
Open the valve
Cleaning of water strainer shall be after every month ± 5 days.
Checking of the valves
Check the valves for smooth closing and opening, it should not be hard, if it is so, the valve preventive maintenance should be carried out as follows
Switch off the pump.
Close the nearby upward and downward side valves.
Open the valve flanges lightly to drain out the water.
After draining the water open the full flanges.
Check the valve steam and valve internals for any damage, for valve seat, gaskets, stem locking nut tightness; if required clean or replace the internals.
Refit the valve, open the both side nearby valves, check for any leakages, check for normal closing and opening operation. If found okay, put the system on or otherwise replace the valve.
The valve checking frequency shall be after every month ± 5 days.
Checking the refrigerant leakage
Check the refrigerant pressure in the refrigerant circuit after every three months. If the refrigerant pressure is below 490 Kpa (g) (71 psi g) at 21deg C or 317 Kpa g (46 psi g) at 10 deg C, call the service engineer of M/s. Trane Chiller.
Checking shall be done on quarterly basis ± 7 days.
Checking of Oil sump level,
Check the oil level in the sight glass, it should be more than 100 mm in the sight glass, if found less, and then call the service engineer of M/s Trane Chillers to charge the oil.
Checking shall be done on monthly basis ± 5 days.
Removing and charging of compressor oil,
The oil is compressor oil sump is under a constant positive pressure at ambient temperature.
To remove oil, open the service valves located on the bottom of the oil sump and drain the oil into a suitable container using the procedure as below
Connect a line to the oil sump drain valve.
Open the valve and allow the desired amount of oil into the container and close the charging valve.
Measure the exact amount of oil removed from the unit.
It is critical to fill the oil lines feeding the compressor when charging a system with oil. It is recommended that to call the service engineer from the M/s Trane for replacing / charging the oil.
Checking of oil filter
Run the chiller on fully unloaded condition for approximately 20 minutes.
Check the oil filter differential pressure by calculating the (difference between the condenser suction pressure and oil pressure) it should not be less than 25 psi, if found less than 25 psi then call the service engineer of M/s Trane Chillers.
Checking shall be done on monthly basis ± 5 days.
Checking of Condenser / Evaporator for Scale, fouling.
Check the condenser/evaporator approach temperature on the screen; it should be less than 5.6°C. If found more than 5.6°C, call the service engineer of M/s Trane Chillers.
Checking shall be done on yearly basis ± 30 days.
Checking of Chilled water pump.
Check for any leakages from the mechanical seal, if found rectify the same.
Check the lubrication of mechanical seal and coupling if required lubricate the same with recommended lubricating grease.
If the pump having coupling provision, Check the condition of coupling between pump and motor, if found damage replaces the same.
Check the pump for any abnormal sound if found, check the bearing impeller and other moving parts, if found damage rectifies the same.
Clean the strainers.
Checking shall be done on quarterly basis ± 7 days.
Checking of instruments.
Check the instruments for proper installations.
Check the instruments for tight end connections and tight contacts; if required tight the same.
The online installed instrument are as follows
Pressure gauge on condenser inlet line
Temperature gauge on condenser inlet line.
Pressure gauge on secondary pump discharge.
Temperature gauge on evaporator outlet
RTD sensor on the discharge of secondary pump.
Checking shall be done on quarterly basis ± 7 days.
Checking of Condenser pump.
Check for any leakages from the mechanical seal, if found rectify the same.
If the pump having coupling provision, Check the condition of coupling between pump and motor, if found damage replaces the same.
Check the lubrication of mechanical seal and coupling if required lubricate the same with recommended lubricating grease.
Check the pump for any abnormal sound if found, check the bearing impeller and other moving parts, if found damage rectifies the same.
Clean the strainers.
Checking shall be done on quarterly basis ± 7 days.
Checking of chilled water pipeline and fittings
Check all the pipe line supports and flange joints and tighten them if found loose.
Check the flange joints nut and bolts on pipeline and fittings for leakages. If any leakage is present then check the gaskets, if found damaged replace the same and tighten the clamp.
Check the insulation and cladding, if required repair the insulation and cladding.
Checking shall be done six monthly ± 15 days.
Recommended oil
Trane Polyolester Oil is the approved oil for the RTWS units. Polyolester oil is extremely hygroscopic meaning it readily attracts moisture. The oil cannot be stored in plastic containers due to the hygroscopic properties. As with mineral oil, if water is in the system it will react with the oil to form acids.
Description Acceptable Levels are as
Moisture content less than 300 ppm
Acid Level less than 0.5 TAN (mg KOH/g)
Preventive Maintenance of Chiller – Electrical
Checking of Crank case Heaters
Switch ON the power supply of the chiller, machine should be in OFF position.
Physically touch the oil sump from outside, it should be hot, if found cold, call the service engineer of M/s Trane Chillers.
Checking shall be done on quarterly basis ± 7 days.
Checking of Terminals, Wiring and Components
Ensure that the power supply to the machine is switched off.
Clean the panel internally and externally by using vacuum cleaner.
Visually check all the power and control wiring and terminals in the electric panel and at all the field instruments for any sign of overheating and loose terminals.
Check and ensure by using appropriate tools that all the wires are properly tightened.
Check and ensure that double earthing is provided to the panel.
Ensure that there is no chance for the entry of dust into the panel.
Ensure that all switches are working.
Checking shall be done on quarterly basis ± 7 days.
Checking of Contactors
Ensure that the power supply to the machine is switched off.
Open contactor contact points cover.
Remove dust from control panel with air blower.
Check all the contacts for pitting and carbon deposits in the contacts.
Clean all the contacts with carbon tetra chloride or with contactor cleaner.
Replace the contacts if found damaged or welded.
Check the earthing of the panel body.
A good earthing shall show less than 2 Volts between the Neutral Wire of the Incoming Power supply and Panel Body.
Checking of contactors shall be done on quarterly basis ± 7 days.
Checking of Pump Motor
Check the insulation resistance of motor winding with the help of meagger.
Check the phase continuity and winding continuity of motor with the help of tong tester.
Physically check the motor terminal box and terminal connections.
Check the voltage and ampere ratings of motor with the help of tong tester.
Check the direction of rotation; it should be as per recommended direction
Checking shall be done after every six month ± 15 days.
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Check the phase continuity and winding continuity of motor with the help of tong tester.
Check the voltage and ampere ratings of motor with the help of tong tester.
Check the direction of rotation; it should be as per recommended direction
Checking of motor shall be done on half yearly basis ± 15 days.
Checking of PLC
Check the PLC for blinking of LED.
Check the display
Check the wiring contacts, if required tight the same.
Checking of PLC shall be done after every six month ± 15 days.
Checking of safety interlocks
If evaporator water flow is not established in 4 minutes and 15 sec, the HMI will de-energizes the evaporator water pump. If the flow returns the evaporator water pump will start.
The chiller is inhibited from running as the ice building process has been normally terminated on the evaporator entering temperature. The chiller will not start unless the ice building command is removed or cycled.
Chiller is stopped by tracer or BMS system, if it is connected to the system.
The chiller is inhibited because of lack of communication with the BMS. This is only valid for 15 minutes after power up.
The chiller will inhibit based on the outdoor air temperature.
The chiller is inhibited from starting due to low condenser temperature.
The chiller will wait for 20 minutes for evaporator water flow rate.
The chiller will wait indefinitely in cool mode for leaving water temperature higher than the chilled water set-point.
The chiller will wait indefinitely in heating mode for leaving temperature lower than the hot water set point.
The chiller will wait up to 4 minutes for condenser water flow.
The chiller will wait up to 30 minutes for condenser water pre run time to allow the condenser water loop to equalize in temperature
High condenser pressure limit; the circuit is experiencing condenser pressure at or near the condenser limit setting. Compressor on the circuit will be unloaded to prevent exceeding limits.
If the saturate temperatures at or near the low refrigerant temperature cutout setting. Compressor on the circuit will be unloaded to prevent tripping.
The compressor must be shut down after the run unload time.
Safety interlocks shall be checked on six monthly basis ± 15 days.
Scheduling other maintenance and checks:
Use a non destructive tube test to inspect the condenser and evaporator tubes at 3 year intervals.
Post Preventive Maintenance of Chiller– CheckList
Whenever any modifications and major works are carried out to the equipment, the same shall be mentioned in the equipment history card as per the respective SOP.
Connect the equipment main power supply and start the equipment.
Ensure that the equipment is running smoothly, without any abnormality.
If any abnormality is observed in the above, same will be attended in co-ordination with User department Head.
Record the Preventive maintenance details shall be record as per Format No. SOP/EN/XXXYYY.
ABBREVIATIONS:
CRF No. : Change Request Form number
SOP : Standard Operating Procedure
PLC : Programmable Logical controller
LED : Light Emitting Diode
BMS : Building management System
REFERENCES:
Operational & Maintenance Manual of Chiller.
DISTRIBUTION LIST:
SOP shall be distributed to following departments Quality Assurance, Engineering as per user request.
ANNEXURES:
Preventive Maintenance Checklist & Record for Chiller : SOP/EN/XXXYYY
Checklist & Records forPreventive Maintenance of Chiller
Equipment Name
Location
Equipment ID
Frequency
Things to be done:
Check List
Remarks
Monthly Check List
Clean all water strainers in chilled water and condensing water piping.
Checking of valves.
Checking of oil sump level.
Checking of oil filter.
Quarterly Check List
Checking of the refrigerant leakages.
Checking of chilled water primary and secondary pump for abnormal sound, leakages, mechanical seal and lubrication.
Checking of installed instruments for proper end connections and wiring contacts.
Checking of condenser pumps for any abnormal sound; leakages; mechanical seal and lubrication.
Checking of crank case heaters.
Checking of terminals; wiring and components.
Checking of contactors.
Half Yearly Check List
Checking of condenser and evaporator for scale and fouling.
Checking of chilled water pipe line and fittings for any leakages, insulation; cladding.
Checking of pump motor.
Checking of PLC.
Checking of safety interlocks.
Yearly Check List
Checking of condenser and evaporator for scale and fouling and de-scaling of the same.
Scheduling other maintenance
Conduct non destructive testing of condenser and evaporator tubes after every 3 years.
