A compressor with a displacement of 20 cfm pumps 17 cfm. What is its volumetric efficiency?

To determine the volumetric efficiency of a compressor, the formula used is:

[ \text{Volumetric Efficiency} = \left( \frac{\text{Actual Volume Pumped}}{\text{Displacement Volume}} \right) \times 100% ]

In this scenario, the compressor has a displacement volume of 20 cubic feet per minute (cfm) and is actually pumping 17 cfm.

Using the formula:

1. Actual volume pumped = 17 cfm

2. Displacement volume = 20 cfm

Plugging the values into the equation yields:

[ \text{Volumetric Efficiency} = \left( \frac{17 \text{ cfm}}{20 \text{ cfm}} \right) \times 100% ]

Calculating this gives:

[ \text{Volumetric Efficiency} = (0.85) \times 100% = 85% ]

Therefore, the volumetric efficiency of the compressor is indeed 85%. This metric indicates how effectively the compressor is moving air compared to its maximum capacity, which is critical for understanding its performance in various applications.