| 1. |
An air compressor operates by converting mechanical energy into pneumatic energy via compression. |
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True |
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False |
| 2. |
Which one of the following characteristics a compressor with a positive displacement pumping has?
- The pressure against which the compressor works rises to higher and higher values as pumping continues. It must be limited by some external pressure control device.
- The rate of free air delivery is highest at 0 psig and very gradually drops to lower values as pressure increases.
- The amount of heat generated progressively rises as pressure increases, causing substantial increases in temperature of both the air handled and the compressor structure
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1 and 2 |
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1 and 3 |
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1,2, and 3 |
| 3. |
Reciprocating piston compressors inherently generate inertial forces that shake the machine. |
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Thus, a rigid frame, fixed to a solid foundation, is often required. |
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Thus, wheels fixed to the bottom of the reciprocating compressors are needed. |
| 4. |
The rocking piston principle (Fig. 16) is another variation of reciprocal compression. In fact, it can be viewed as a combination of the diaphragm and piston principles. |
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True |
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False |
| 5. |
A rotary vane compressor is used when: |
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We need high pulsation and high vibration in the air output |
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We need no pulsation and minimum vibration in the air output. |
| 6. |
A rotary vane compressor is commonly used for moderately high air flows at pressures under 30 psig, although some rotary vane designs can provide pressures of 200 psig. Rotary vane units generally have lower pressure ratings than piston units because of more difficult sealing problems and greater sensitivity to thermal effects. |
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True |
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False |
| 7. |
Figure 19 – is a basic operation of single stage/two cylinder air compressor. This piston type compressor has two cylinders and the compression action is: |
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Single stage |
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Multi-stage |
| 8. |
In multi-stage compression, the gas moves from one chamber to another |
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True |
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False |
| 9. |
Centrifugal compressors are best suited to the continuous movement of large air volumes through small pressure ranges. Fig. 21 shows the basic operation. Air leaving a rotating impeller passes radially outward to the casing. Centrifugal action builds up: |
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Velocity |
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Pressure |
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Both velocity and pressure |
| 10. |
In selecting the size and type of an air compressor, which one of the following components the designer must consider. |
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How much pressure and air flow is required to meet specific application needs. |
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The drive power requirements for the compressor and how they will be met. |
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Cost |
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Space |
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Weight limitations |
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Needs for oil- free or pulseless air. |
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All of the above |
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