Please answer true or false for each question. Part I: Indicate whether true or
ID: 1714610 • Letter: P
Question
Please answer true or false for each question.
Part I: Indicate whether true or false T or 1 point each correet answer T Cavitation in a pump occurs when the absolute pressure is les than the vapor pressure or water. The water vaporizes and forms small bubbles that collape when they reach a region of higher pressure in the pump. This results in vibrations that can damage the pump. The net positive suction head (NPSH) is the total absolute head above the vapor pressure o the uid at the eye or Given three pipes in Parallel. The head loss is the eams in each pipe and the now rate is the same in each pipe. always proceed in the downstream, direction. That is becaus wrhen two pumps are connected in parallel in a pipeline. the discharge is increased but the pressure head remains the The Hazen-Williams coefficient varies with pipe material and age, and is independent of flow rate. Therefore, the Hazen-Williams equation applies only to fully turbulent now. where tully turbulent flow is detined as flow with Reynosidx nurnber Ihat corresponds to the t1 at (horizontal) portion of th Mloody diagram. renea portion of the Mooy direction of now) even Given an MI 1low profile, the specifis energy decreases in the downstream direction (direction of now even though Energy grade line (EGL) is defined as the total enersy ata pont in a nuid system. EGL is the sum of the pressure headd, clevation head and velocity head terms. In open ohannel flow, the pressure head term is equivalent to the Accordingly, EGL ix th xum of the depth of flow depth of now y or channels sloped less than 10 elevation above some horizontal datum, and velocity head. Another energy much for open channel flow is specifie energy, which is the total energy measured relative to the channel bed. EAduplex station has two pumps. Typical South Carolina practice has the two pumps altenating lead and lag status. A uch, duplex stations have three switch elevations: lead pump on, lag pump on. and pumps ofr. The specific norgy curve is obtai nod by plotting KPecific energy for range of depth values (y values) fer giver discharge in a channel. The curve falls in the first quadrant, with asymptotes of the y E (43° line and the abscissa CE axis). The ourve has three distinot portions corresponding to saberitieal, critical and Critical flow (depth) occurs at the point of minimum specifie energy, where the Froude number equals 1 The depth o low at this point is termed the oritioal depth and is designated as y At depths below ye. the low is classified as subcritical becaus, the depth of flow is below (sub) the critical depth, and at dep ths greater than y . th flovv is elaxxified ax xuPereri tical, because the depth of now/ iss greate than the eritieal depth. The governing relationships for network analysis uing the Hardy-Cross method are nodal sontinuity and energy conservation round prirnary !0p. In the esase or networks with fixed grade nodex, the energy equaticr1 18 writter between any two nxed grdes nodes. A sequence or pipe oonnecting any two nxed grade nodes is known as path. Given a system with n fxed grade nodes, there will be n 1 paths point (cross-section) along a channel. Unitorm now is now steady now is now that does not ohange with time at that does not change in space along a channel profile analysis involves determination of the non-uniform flow depth along channel _copen channel flows are elaxxified aas. Huberítieal, critical, or supercritical by eornparing the uniform and criticalExplanation / Answer
1. True, because when vapour reaches to discharge side, it no longer sees vacuum which is compressed back and this occurs vibrations which are harmful to pump.
2. True, definition of Net positive suction head.
3. False, All three pipes will be having different flow rates.
4. True.
5. True, as pipe has its own capacity to carry flow at different velocities.
6. False, it is controlled by gravitational forces.
7. True.
8. False, it remains unchanged unless until mass is unchanged of flow.