Term
| What are the Two major categories of Pumps? |
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Definition
| Positive Displacement Pumps and Non-Positive Displacement Pumps |
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Term
| Name Four general classifications of pumps |
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Definition
| Rotary, Jet, Centrifugal, Reciprocating |
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Term
| Explain the operation of a Fee-Water Injector |
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Definition
| It uses a condensable gas to entrain a liquid and discharge against a higher than either the motive or suction pressures. |
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Term
| What is the maximum feed-water temperature when using injectors? |
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Definition
| 130° to 150° is considered the maximum temperature. |
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Term
| What are the operating mediums for duplex pumps? |
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Definition
| Duplex pumps can operate on steam, compressed air, and water. |
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Term
| How do you set the valves on a duplex pump? |
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Definition
1. Close steam and exhaust valves. Drain pump and Tag Out Lock Out.
2. Center the Pistons
3. Plumb the Rocker arm
4. Square the valve over the ports
5. Equalize the lost motion
6. Move piston off center |
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Term
| What is meant by the term "Lost Motion"? |
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Definition
| Lost Motion is the amount the valve rod moves without moving the valve gear |
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Term
| What is the effect of too much lost motion? Not enough Lost Motion? |
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Definition
| Too much Lost Motion will cause the pistons to trike the heads, Not enough Lost Motion will cause the pump to Short stroke. |
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Term
| What is a Cushioned Valve? |
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Definition
| They are manual valves located at each end of the steam chest, they act as an added control to prevent the steam piston from striking the cylinder heads when the pump operates at high speeds. |
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Term
| What is the area of a piston 6" in diameter? |
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Definition
Area = d² X .7854.
6 X 6 X .7854 = 28.27 in² |
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Term
| Does a Duplex Pump displace an equal amount of water on the forward and reverse stroke? Why? |
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Definition
| Yes, because the net effect of the piston rod on the displacement is equal on both sides of a duplex pump. |
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Term
| What type of pump is a Metering Pump? A Vacuum Pump? |
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Definition
| A metering pump is a Positive displacement Pump and a Vacuum pump is also a Positive displacement Pump |
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Term
| What type of service would you expect to see a Rotary Pump? A Gear Pump? |
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Definition
| Rotary pumps and Gear pumps are typically used to pump heavy fuel oils |
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Term
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Definition
| The sudden formation and collapse of low pressure bubbles in water by mechanical forces. This occurs at the inlet of a centrifugal pump when the temperature of the water is too hot or when the suction is too low. |
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Term
| Explain what you would do if a pump began to cavitate |
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Definition
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Term
| What is the best way to avoid pump Cavitation? |
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Definition
| Make sure there is enough water at the correct temperature at all times |
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Term
| Explain the operation of a Centrifugal Pump |
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Definition
| A Centrifugal pump has an impeller attached to the shaft, as the impeller rotates, water enters the center and is thrown outward by Centrifugal force. The water leaves the impeller at a high velocity which is converted to pressure by a volute. |
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Term
| Name three advantages and disadvantages of a Centrifugal Pump. |
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Definition
Advantages: Cost-Effective, Few moving parts, Easy to use, Low Vibration
Disadvantages: Can only pump water, Uses electricity, can break easily, Cavitation, alignment is critical, Ineffective at some loads |
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Term
| Define Head, NPSH, and Velocity Head. |
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Definition
Head: The pressure Gravity adds
Net Positive Suction Head: The minimum suction conditions to prevent cavitation in a pump.
Velocity Head: The kinetic energy per round or the vertical distance a liquid would have to fall to acquire the stated velocity. |
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Term
| What do the numbers 8 X 6 X 12 refer to in a Duplex Pump? |
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Definition
The first number (8) = Diameter of the steam piston in inches.
The second number (6) = Diameter of fluid piston in inches.
the Third number (12) - Length of the stroke in inches. |
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