# Merms Chapter 18 (Hydraulic Machines)



## Clydeman (Dec 7, 2010)

I started going in some depth through the fluids section of MERMS (starting at 14) a few weeks back. I just finished going through 18 &amp; 19.

Much of the information in Chapter 18 (Hydraulic Machines) is new to me. I am fine with Chapters 16 &amp; 17 (Fluid Flow &amp; FLuid Dynamics) and have vague memories of the subject matter from my Fluids course.

Chapter 18 though worries me a little bit. Does MERMS do a good job of summarizing this subject? I have pulled out my Fluids book and it seems like Chapter 18 goes much futher into application (pump sizing and selecting) than a theoretical Fluids class deals with.

Is there better material out there or should I simply rely on MERMS? A lot of the Chapter 18 sample problems seem a lot more involved than I would expect on the test.

I would imagine most fluid problems would involve Bernoulli, impulse momentum, hydrostatic pressure or buoyancy.

I realize I need to be careful not to focus to greatly on any one area (a problem I will likely have in studying for the PE).

Any thoughts.


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## navyasw02 (Dec 7, 2010)

Nathan Satter said:


> I started going in some depth through the fluids section of MERMS (starting at 14) a few weeks back. I just finished going through 18 &amp; 19.
> Much of the information in Chapter 18 (Hydraulic Machines) is new to me. I am fine with Chapters 16 &amp; 17 (Fluid Flow &amp; FLuid Dynamics) and have vague memories of the subject matter from my Fluids course.
> 
> Chapter 18 though worries me a little bit. Does MERMS do a good job of summarizing this subject? I have pulled out my Fluids book and it seems like Chapter 18 goes much futher into application (pump sizing and selecting) than a theoretical Fluids class deals with.
> ...


I found the MERM to be the best for fluids, thermo, and heat transfer (not as good with heat xfer, but all you need). Stick with the MERM and do practice problems from those chapters and you'll be fine. I dont remember which chapters were which, but get really familiar with the pump horsepower tables, head loss calculations, pipe equivalent lengths, and all that sort of thing. You'll see tons of practice problems on those.


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## MadDawg (Dec 7, 2010)

Nathan Satter said:


> I started going in some depth through the fluids section of MERMS (starting at 14) a few weeks back. I just finished going through 18 &amp; 19.
> Much of the information in Chapter 18 (Hydraulic Machines) is new to me. I am fine with Chapters 16 &amp; 17 (Fluid Flow &amp; FLuid Dynamics) and have vague memories of the subject matter from my Fluids course.
> 
> Chapter 18 though worries me a little bit. Does MERMS do a good job of summarizing this subject? I have pulled out my Fluids book and it seems like Chapter 18 goes much futher into application (pump sizing and selecting) than a theoretical Fluids class deals with.
> ...



While studying I pulled out my college textbooks from fluids and thermo, and it's obvious that the textbooks are written more towards the theory while the MERM is more focused on actual application of the theory. Big portions of the textbooks focused on deriving the equations that on the test (in the limited amount of time given) you just need to know which equation to use and which units the formula is in (the first page of each chapter in Lindeburg defines this so you don't need to guess whether to use feet or inches, etc.)

Most of the topics in Ch 18 were new to me, but working the practice problems in NCEES and 6 min solutions helped a whole lot.


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## Capt Worley PE (Dec 8, 2010)

I wish I'd had the MERM in college.

Trust the MERM.


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## Master slacker (Dec 8, 2010)

Looking at my MERM on my shelf, I can say that I remember using only the MERM in the test. It was more than adequate for hydraulics.


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## mechaniac (Dec 14, 2010)

Can one rely only on MERM for thermo? I find this section very brief. I'm thinking of taking the T&amp;F depth.


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## MadDawg (Dec 14, 2010)

mechaniac said:


> Can one rely only on MERM for thermo? I find this section very brief. I'm thinking of taking the T&amp;F depth.


I took T&amp;F and brought my thermo book--didn't take it out of the box. The only books I used besides the MERM were steam tables (the MERM would have been sufficient but the separate steam tables helped b/c I kept my MERM open to the applicable section instead of flipping back to the appendix constantly) and my machine design book for one quick definition-type problem. The answer to the MD problem was probably in the MERM but I knew what section to go to in Shigley's so that saved a few seconds.

If I have to do it all again in April I'll bring all my books again though--a sore back is better than sitting in the test knowing the answer to a simple question is in a book you left at home! And now I know I can bring a backpack/rolling suitcase instead of just a bankers box!


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## RobertR (Jan 13, 2011)

You don't need much more than MERM (and a few others) for the exam. Taking college textbooks with you is a waste of time.


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## momech (Jan 14, 2011)

RobertR said:


> You don't need much more than MERM (and a few others) for the exam. Taking college textbooks with you is a waste of time.


I agree. I only used the MERM and Cameron for the entire exam (morning and T&amp;F depth).


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## Relvinim (Jan 17, 2011)

If I were you I would get real familiar with Hydraulic machines chapter. When you start working on all the sample exams, NCEES, Lindberg, 6MS, etc...you will see quite a bit of questions on pumps. Fortunately it's mostly basic stuff andI think the MERM has all you need to know. I can't speak for the the Depth section since I did Machine Design but for the breath section I was prepared enough. And BTW all I needed for MD was the MERM and Shigley Mechanical Engineering Design.


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