CEM Compressed Air and Power Systems 1

Question 1

Compressed air systems are considered energy-intensive because:

Accepted Answer

Only 10-15% of electrical input is converted to useful work at the point of use; the rest is wasted as heat

Answer

Compressors run at 100% mechanical efficiency

Answer

Compressed air is always produced at higher pressure than needed

Answer

Compressor motors always operate at unity power factor

Question 2

Reducing compressed air system header pressure by 2 psig typically reduces compressor energy consumption by approximately:

Accepted Answer

0.5-1%

Answer

0.1%

Answer

5-10%

Answer

20-30%

Question 3

In a compressed air system, air leaks are significant because:

Accepted Answer

Leaks waste compressed air continuously, forcing compressors to run longer and consume more electricity

Answer

They cause pressure surges that damage pneumatic tools

Answer

Leaks introduce moisture into the compressed air system

Answer

Leaks cause excessive pressure buildup in headers

Question 4

A compressor with a modulating control will save more energy than one with a load/unload control because:

Accepted Answer

Modulating control continuously matches compressor output to actual demand, reducing unloaded running losses

Answer

Modulating control maintains full-load current regardless of demand

Answer

Load/unload control requires a larger receiver tank than modulating control

Answer

Modulating control operates the compressor at higher pressure

Question 5

Heat recovery from compressed air systems is feasible because:

Accepted Answer

About 80-93% of electrical energy input to compressors is converted to heat, which can be recovered for space or water heating

Answer

Compressed air cools significantly during compression

Answer

Compressed air heat is at temperatures suitable for steam generation

Answer

Compressor heat recovery reduces the need for cooling towers

Question 6

Pressure/flow controllers installed in compressed air systems save energy by:

Accepted Answer

Decoupling supply and demand sides, allowing lower supply pressure while maintaining stable header pressure for end uses

Answer

Increasing system pressure to reduce compressor run time

Answer

Eliminating the need for air dryers

Answer

Increasing receiver tank volume automatically