Fluid Mechanics - Study Mode
[#721] With increase in the temperature, viscosity of a liquid
Correct Answer
(B) Decreases
[#722] A centrifugal pump has the following specifications: Power = 4 H.P.
Speed = 800 rpm Head = 8 metres Flow = 1000 litres/minutes. If its speed is halved, then the new head will be __________ metres.
Correct Answer
(A) 2
[#723] With increase in pump speed, its NPSH requirement
Correct Answer
(B) Increases
[#724] With increase in the shear rate, the apparent viscosity of pseudoplastic fluids
Correct Answer
(B) Decreases
[#725] Air vessel provided in a reciprocating pump
Correct Answer
(D) None of these
Explanation
Solution: What is a Reciprocating Pump? Imagine a pump that uses a piston (like in a car engine) to push fluid. That's basically a reciprocating pump. Because of this piston movement, the flow isn't constant
it goes in pulses. What is an Air Vessel? An air vessel is like a small tank filled with air, connected to the pipe near the pump. Why do we need it? Let's look at the options: Option A: Smoothens the flow by avoiding pulsations This is the correct answer. Think of the air in the vessel as a cushion. When the pump pushes hard (during its stroke), some of the fluid goes into the air vessel, compressing the air. When the pump's push is weaker, the compressed air pushes the fluid *out* of the vessel. This helps to even out the flow, making it smoother and less jerky. Option B: Increases the volumetric efficiency of the pump Volumetric efficiency is about how much fluid the pump *actually* delivers compared to how much it *should* deliver theoretically. While smoother flow *can* indirectly help a little, it's not the main reason for the air vessel. Option C: Saves the pump from the danger of cavitation Cavitation is when bubbles form in the liquid due to low pressure and then collapse violently, damaging the pump. While air vessels can help *reduce* pressure fluctuations, they're not primarily designed to prevent cavitation. Other measures (like increasing the inlet pressure) are more important for that. Option D: None of these Since Option A is correct, this is wrong. Therefore, the primary purpose of an air vessel in a reciprocating pump is to smooth out the flow and reduce pulsations.