Are You A Pump Ninja?

1. For a given size piping system, adding a second identical pump in parallel will …

Increase the flow rate to a point determined by the system curve.

Double the flow.

Double the pressure (head).

None of these answers is correct.

Adding a second identical pump in parallel to a piping system will increase the flow rate. However, the increase in flow rate will be limited by the system curve, which represents the relationship between flow rate and pressure drop in the system. Therefore, the flow rate will increase up to a point determined by the system curve, but it will not necessarily double.

Explanation

Adding a second identical pump in parallel to a piping system will increase the flow rate. However, the increase in flow rate will be limited by the system curve, which represents the relationship between flow rate and pressure drop in the system. Therefore, the flow rate will increase up to a point determined by the system curve, but it will not necessarily double.

2. When starting up a centrifugal pump, the suction valve should always be ...

Fully open.

Partially open, then opened the rest of the way a few minutes afterward.

Fully closed.

It doesn't matter, because it is a centrifugal pump.

When starting up a centrifugal pump, the suction valve should always be fully open. This is because a centrifugal pump relies on the flow of liquid through the impeller to generate pressure and create the necessary suction. By fully opening the suction valve, it allows for maximum flow of liquid into the pump, preventing any potential cavitation or damage to the pump. Partially opening the valve or keeping it fully closed can restrict the flow and cause issues with the pump's performance. Therefore, it is important to always start the centrifugal pump with the suction valve fully open.

Explanation

When starting up a centrifugal pump, the suction valve should always be fully open. This is because a centrifugal pump relies on the flow of liquid through the impeller to generate pressure and create the necessary suction. By fully opening the suction valve, it allows for maximum flow of liquid into the pump, preventing any potential cavitation or damage to the pump. Partially opening the valve or keeping it fully closed can restrict the flow and cause issues with the pump's performance. Therefore, it is important to always start the centrifugal pump with the suction valve fully open.

3. Water will boil at what temperature (F)?

It depends on the pressure.

212

100

33

600

The boiling point of water is not a fixed temperature but rather depends on the pressure applied. At sea level, water boils at 212 degrees Fahrenheit, but at higher altitudes where the atmospheric pressure is lower, water boils at a lower temperature. Similarly, at higher pressures, such as in a pressure cooker, water can reach higher temperatures before boiling. Therefore, the correct answer is that the boiling temperature of water depends on the pressure.

Explanation

The boiling point of water is not a fixed temperature but rather depends on the pressure applied. At sea level, water boils at 212 degrees Fahrenheit, but at higher altitudes where the atmospheric pressure is lower, water boils at a lower temperature. Similarly, at higher pressures, such as in a pressure cooker, water can reach higher temperatures before boiling. Therefore, the correct answer is that the boiling temperature of water depends on the pressure.

4. Given a specific fluid to be pumped, at what viscosity range should you begin to apply viscous corrections to the hydraulic performance for a centrifugal pump?

5 to 15 centipoise

Above 300 centipoise

Above 600 centipoise

Centrifugal pumps do not require viscosity corrections.

Viscous corrections should be applied to the hydraulic performance of a centrifugal pump when the viscosity of the fluid being pumped falls within the range of 5 to 15 centipoise. This means that if the fluid's viscosity is below 5 centipoise or above 15 centipoise, there is no need to make any adjustments to the pump's performance based on viscosity.

Explanation

Viscous corrections should be applied to the hydraulic performance of a centrifugal pump when the viscosity of the fluid being pumped falls within the range of 5 to 15 centipoise. This means that if the fluid's viscosity is below 5 centipoise or above 15 centipoise, there is no need to make any adjustments to the pump's performance based on viscosity.

5. Which fluid, when subjected to cavitation conditions, will normally create the most damage in a pump (assuming all other conditions are the same)?

Water at 68 F

Gasoline (87 octane) at 75 F

Ethylene glycol mixed with water at 50 percent (180 F)

Ethanol at 75 F

Naval jet fuel JP5 at 68 F

Water at 300 F

When subjected to cavitation conditions, the fluid that will normally create the most damage in a pump is water at 68 F. Cavitation occurs when the pressure of a fluid drops below its vapor pressure, causing the formation and collapse of vapor bubbles. These collapsing bubbles can create intense shockwaves that can erode the pump's impeller and other components, leading to damage. Water is particularly prone to cavitation due to its low vapor pressure, and at 68 F, it is in a temperature range where cavitation is more likely to occur.

Explanation

When subjected to cavitation conditions, the fluid that will normally create the most damage in a pump is water at 68 F. Cavitation occurs when the pressure of a fluid drops below its vapor pressure, causing the formation and collapse of vapor bubbles. These collapsing bubbles can create intense shockwaves that can erode the pump's impeller and other components, leading to damage. Water is particularly prone to cavitation due to its low vapor pressure, and at 68 F, it is in a temperature range where cavitation is more likely to occur.