In large capacity centrifugal compressors, the upper limit is how many tons?

• A. 1000
• B. 2500
• C. 5000
• D. 7500

Answer: (C)

The concept being tested is the practical size limit for a single centrifugal compressor in large cooling plants. In this application, centrifugal machines are used for very high flow with modest pressure rise, but there is a practical cap on how much capacity a single unit can efficiently and safely handle. That cap is about five thousand tons of refrigeration. One ton equals 12,000 BTU per hour, so five thousand tons amounts to roughly 60 million BTU per hour (60 MBH). Beyond this, achieving stable operation, acceptable surge control, and feasible motor and bearing loads becomes impractical, so larger cooling needs are met by multiple compressors in parallel or by different equipment.