|Centrifugal, Screw & Reciprocating
Compressor Type Chillers
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Magnetec Inspection Inc.
1159 East North St.,
Bradley, IL 60915
815 802-1363 T
For medium-sized to large facilities, centrifugal chillers are a popular choice. They offer high
operating efficiency and low maintenance requirements in a relatively compact design. But while centrifugal chiller PM
requirements might be low, their maintenance is critical. Ignoring ECT tube inspection may drastically reduce
performance and efficiency, while contributing to frequent breakdowns and early failure.
The most serious maintenance problems facing centrifugal chillers are fouling, corrosion and air leaks. Fouling occurs
when solids in the chilled and condenser water drop out of suspension and attach themselves to heat transfer surfaces
within the chiller. Even a thin layer of solids can dramatically reduce a chiller’s operating efficiency.
Corrosion, an electrochemical process that taking place within a chiller attacks metal surfaces, decreases the efficiency of
heat-transfer surfaces and can lead to the destruction of individual tubes. The rate of corrosion is determined in part by
the quantity of dissolved oxygen in the water, the degree of alkalinity or acidity of the circulating water, and the
concentration of dissolved solids in the water.
Since many centrifugal chillers are low-pressure units, a leak in the system can allow air and moisture to enter and mix
with the refrigerant. Both of these substances reduce the chiller’s capacity and operating efficiency. Moisture also mixes
with refrigerant to form an acid that attacks internal components.
Corrosion is best controlled through a water-treatment program that monitors conditions within the chilled and condenser
water systems and adds in the proper amount of chemicals.
While centrifugal chillers have been the industry
standard for years, absorption units are gaining
ground. The cost of electricity, particularly for those
who pay high demand charges or peak rates, has led
many facilities to consider chillers driven by alternative
fuels. With its ability to use steam or natural gas, the
absorption chiller gives users that flexibility.
Proper PM of absorption chillers is critical for their
efficient operation. Like centrifugal units, absorption
chillers require a comprehensive inspection of the
tubes to monitor for active corrosion and/or fouling…
Depending on chiller run time, managers should add a
comprehensive ECT inspection of the chiller tubing.