CEM Compressed Air and Power Systems

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

The compression process generates large amounts of heat and has multiple energy conversion losses; only about 10-15% of electrical input reaches the end-use tool or process as useful work.

Question 2

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

Accepted Answer

0.5-1%

Answer

As a rule of thumb, each 2 psig reduction in discharge pressure reduces compressor energy consumption by approximately 0.5-1%, providing an easy, no-cost savings opportunity through pressure optimization.

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

Leaks in typical industrial compressed air systems waste 20-30% of total compressor output, requiring compressors to run additional hours to compensate for the constant air loss.

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 controls throttle compressor inlet valves to precisely match output to demand, while load/unload controls cycle between full load and unloaded (wasteful) operation.

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

Since 80-93% of compression energy becomes heat in the compressed air and compressor components, this heat can be recovered using heat exchangers to provide useful building heat or hot water.

CEM - Certified Energy Manager Practice Test

CEM - Certified Energy Manager Practice Test

CEM Compressed Air and Power Systems