WAZIPOINT Engineering Science & Technology: Maintenance Procedure of Centrifugal Water Chiller

Thursday, April 25, 2019

Maintenance Procedure of Centrifugal Water Chiller

Maintenance Procedure of Centrifugal Water Chiller

What is the maintenance procedure of centrifugal water chiller and how keep your chiller on trouble-less operation. Yes, of course maintenance is important fact for this. Proper maintenance not only give you hassle free smooth operation, it also ensure optimize your property operating lifetime. 

Most of manufacturer offer some maintenance rules and procedure of their equipment. If user follows these instruction and carry-out the maintenance work correctly, machinery will give maximum usability. 

To keep fit your centrifugal water chiller following general maintenance is required. Although some of the information presented here commonly what is applicable for other types of chiller. 

Maximum time centrifugal chiller after installing put into continuous operation without full-time attendant using BMS (Building Management System) or simple clock system. Actually water chiller is designed for maximum consistency with a minimum amount of maintenance. 

However, certain routine maintenance procedures are either required or recommended based on daily completed and reviewed operating log.

For maintenance a chiller we can consider the following major fields:

Operating log Mechanical components Heat-transfer surfaces Fluid analysis

Operating log:
Chilled water inlet and outlet temperatures and pressures
▲ Chilled water flow
▲ Evaporator refrigerant temperature and pressures
▲ Evaporator approach temperature
▲ Condenser water inlet and outlet temperatures and pressures
▲ Condenser water flow
▲ Condenser refrigerant temperature and pressures
▲ Condenser approach temperature
▲ Oil pressures, temperature levels
▲ Addition of refrigerant
▲ Addition of oil
▲ Vibration levels

Special attention should be given to:

■ Reviewing the operating log and trends
■ Observing the oil pressure drop to determine if the oil filter needs to be replaced
■Monitoring evaporator and condenser approach temperatures
■ Observing and recording the oil level
■ Monitoring purge pump-out operation

Mechanical Components:

Required maintenance
◆ Compressor and motor: no maintenance required
◆ Controls: no maintenance or calibration required

Recommended maintenance

◆ Visually inspect overall unit
◆ Inspect safety controls and electrical components
◆ Tighten electrical connections
◆ Check for leaks

Other design-specific requirements

◆ Change oil when oil analysis dictates
◆ Replace oil filter periodically
◆ Replace filter drier periodically
◆ Clean oil strainers annually
◆ Check shaft alignment annually
◆ Check coupling annually
◆ Replace shaft seal every 2 to 4 years
◆ Compressor teardown inspection every 5 to 10 years

Heat Transfer Surfaces:

Recommended maintenance
◆ Use a qualified water treatment specialist
◆ Clean condenser tubes as needed
◆ Clean water-side strainers
◆ Test tubes every 3 years

Fluid Analysis:

Oil analysis

◆ Conduct annual analysis to verify system integrity
◆ Measure oil pressure drop to determine if filter needs changing
◆ Measure charge

Refrigerant charge

◆ Conduct analysis of refrigerant
◆ Inspect purge system

Why perform regular oil analysis?

◆ Helps reduce maintenance costs
◆ Detects problems without compressor disassembly
◆ Extends service life of oil charge
◆ Reduces environmental problems related to oil disposal
◆ Helps maintain compressor efficiency and reliability
◆ Helps lower refrigerant emissions

As for any mechanical equipment a daily visual inspection is recommended to check for oil leaks, gas leaks, water leaks, condensation, loosened electrical or control wiring, any signs of corrosion. Especially controls and electrical components should be checked. A qualified engineer or service technician need to check the chiller annually. 

Most of the microprocessor-based chiller is automated and user-friendly, connected with BMS (Building Management System), they generate signal and alarm or diagnostic massage when problem occurs. 

The chiller compressor and motor assembly in direct-drive; the hermetic compressor designed chiller actually removed oil and refrigerant seal replacement frequently, they need some periodic maintenance.

Oil and refrigerant analysis is a key preventive maintenance measure and should be conduct regularly. Oil and refrigerant charges, and examining the trends of this data can help identify potential problems before they occur.

Regular oil analyses can be used to determine proper oil change intervals and predict major problems before they occur, oil analysis is an important annual maintenance job required for centrifugal  water chillers which may be conducted more frequently for chillers that run  continuously.

Refrigerant analysis measures contamination levels and determines suitability for continued use also helps to extend the life of the existing charge and ensures that the chiller is operating at peak efficiency.


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