# Errors in new PE-Mechanical reference Handbook V1.1



## Saurabh9978 (Feb 3, 2020)

Hello All

I am preparing for the PE Machine Design and Materials 

I have observed some errors (according to me) for the PE Mechanical reference book V1.1

have you observed any ?

for example page : 184 welding load calculation 

area mentioned for the fillet weld is not correct


----------



## Edgy Cheesy Graphite PE (Feb 3, 2020)

Yep. Check out this thread. It's mostly Thermal-Fluids focused because one of EB's members is a thermal-fluids course creator, so he's been reviewing it very carefully and submitting errors to NCEES. But I'd definitely like to see more MDM stuff posted there.

FYI, I think on page 4ish, they switch from version 1 to version 1.1, but I don't know if all the v1 stuff was corrected.


----------



## OldSquaw (Feb 3, 2020)

Make sure to log in to your NCEES account and use the chat feature to report errors. Every time I report an error, the same test development engineer responds to me very quickly. So they will pay attention if you report an error.


----------



## Abogos (Mar 7, 2020)

Also, have you noticed that the nomenclature is messed up or is it my pdf reader? 
I downloaded the 1.1 version of the manual which is the latest and in the MDM section , which I prepare for, the parentheses or symbols are all messed up. Is anyone else experiencing this the problem?


----------



## MikeGlass1969 (Mar 7, 2020)

I have seen that with other pdf viewers.  You should only be using the Adobe Acrobat, or whatever they call it today, to view or printing the the manual.


----------



## Abogos (Mar 7, 2020)

MikeGlass1969 said:


> I have seen that with other pdf viewers.  You should only be using the Adobe Acrobat, or whatever they call it today, to view or printing the the manual.


Alright, Good to know the manual is ok.


----------



## MikeGlass1969 (Mar 7, 2020)

Well,  I didn't say it was ok.  They are still working out the bugs out of it.  Just best to use Acrobat.


----------



## Abogos (Mar 7, 2020)

MikeGlass1969 said:


> Well,  I didn't say it was ok.  They are still working out the bugs out of it.  Just best to use Acrobat.


Yup i meant the problem i was having wasn’t due to the manual, i know the manual itself is still being improved.


----------



## Engineer_562 (Apr 16, 2020)

I have a quick question about mechanical reference handbook for CBT Exam. The NCEES website says you can download it free if you log into your account. I did but where do I go next? I have not registered for exam. Is that why I can’t have access to it? Is it free for public or just for people who have registered?


----------



## FA_Mechanical engineer (Apr 16, 2020)

You should be able to download without registering. it is open for public to download for free. Highly suggest to get it binded at a local store and use it like other hard cover reference manuals. It is a 500 page manual which is very focused in equations, charts and ASHARE tables etc and I personally think it works out really well during the preparation process.


----------



## Dr. Barber (Apr 16, 2020)

Engineer_562 said:


> I have a quick question about mechanical reference handbook for CBT Exam. The NCEES website says you can download it free if you log into your account. I did but where do I go next? I have not registered for exam. Is that why I can’t have access to it? Is it free for public or just for people who have registered?


Once you log in to your account you can get it from the "View Reference Handbooks" link


----------



## Engineer_562 (Apr 17, 2020)

thank you Dr.Barber. This was really helpful. I guess they can add to their description " Log into your account, go down and click on view reference handbooks" instead of just saying you can get it from your NCEES account.


----------



## Dr. Barber (Apr 17, 2020)

Engineer_562 said:


> thank you Dr.Barber. This was really helpful. I guess they can add to their description " Log into your account, go down and click on view reference handbooks" instead of just saying you can get it from your NCEES account.


I hear you. I had a hell of a time locating it when it first came out.


----------



## Ijoinedbecausecovid (Apr 24, 2020)

I'm studying for the MDM and there are a lot of errors.


----------



## Dr. Barber (Apr 24, 2020)

Ijoinedbecausecovid said:


> I'm studying for the MDM and there are a lot of errors.


...and I'm writing study materials for Thermal Fluids Systems and there are quite a few errors in those sections as well. Please be sure to report the errors to them. Also, if you don't mind post them here so others can see them and give you feedback.


----------



## Ijoinedbecausecovid (Apr 25, 2020)

Dr. Barber said:


> ...and I'm writing study materials for Thermal Fluids Systems and there are quite a few errors in those sections as well. Please be sure to report the errors to them. Also, if you don't mind post them here so others can see them and give you feedback.


Ok cool, I've been sending them in as I find them. Don Colman from NCEES is probably tired of me by now haha. I'll post the ones I've found below. I could be incorrect in my diagnosis so please let me know if I goofed.

#1 Pg. 157 
The 'Vibration Transmissibility' equation should not have the r^2 in front of the equation. One of the PPI problems alerted me to this. I also found a second reference without the r^2: https://nptel.ac.in/content/storage2/nptel_data3/html/mhrd/ict/text/112107212/lec18.pdf

#2 Pg. 60
 Under 'Equivalent Masses', the equation/diagram for 'Masses on a hinged bar' is wrong. The length ratios should be in reference of the total bar length, not the length from the hinge to the first mass. One of the PPI problems alerted me to this. I can't find a corroborating source, but logically the NCEES handbook equation makes no sense.

#3 Pg. 174
 The equation solving for D in the figure in row 3 column 1 should use the variable 'y', not 'v'. Probably a typo. 

#4 Pg. 9
Regarding the chart for relating viscosity and temperature of various SAE oils. The Y axis shows viscosity in units of reyn. I think the Y axis needs a x10^-6 (i.e. E-6).

#5 Pg 197
The Basic Pitch Diameter of a #6 UNC screw is a typo. Should be 0.1177, not 1.1177.

#6 Pg 196
The 'Tensile Stress Area' units should be in^2, not in. This is goofed in all of the charts.

Not necessarily mistakes, but, there are a lot of equations that have variables with no legend so you have to just know/guess what the variable is. I don't know if NCEES intends to supply ambiguous equations or not. There is also a lack of variable consistency in the handbook. For example, 's' is used for distance in pg 119 'Work' equations. Everywhere else it is 'x'. Another thing I noticed while studying was that the chart 'Approximate Values of Effective Length Factor, K' on pg. 150 is not always clear depending on how the question is asked. At least in the PPI practice problems (and in the NCEES practice  test #56 although the picture clarifies), the rod end condition will be described using words like 'pinned' or 'securely attached' or ' free to move'.  You just need to know what the English words translate to. Another weird thing is Pg 156. where it seems like they just lumped some general vibration equations in with the 'Torsional Vibration' section. Everything from 'critical damping constant' to ' damped natural frequency' is not strictly torsional vibration so it is weird that its in that section.  Pg. 185 is not clear that the 'Unit Second Moment of Area' refers to per unit throat length, not per unit weld size. Maybe that is obvious to someone who works with welds...

One of their replies makes it seem like these might not be fixed before I take the test:
"I will forward your comment to the committee responsible for the Mechanical PE Exam Reference manual for review. This may not happen before you take your exam as they do not meet frequently. If you have any concerns during your exam on handbook content please use this form of communication to let us know so we can review the item and the handbook."

Hope that helps some people!


----------



## ChooChooEngineer_PE (May 14, 2020)

Didn't know the Europeans had switched to kpsi and inches... (p.194)


----------



## DKS (May 14, 2020)

Ijoinedbecausecovid said:


> #1 Pg. 157
> The 'Vibration Transmissibility' equation should not have the r^2 in front of the equation. One of the PPI problems alerted me to this. I also found a second reference without the r^2: https://nptel.ac.in/content/storage2/nptel_data3/html/mhrd/ict/text/112107212/lec18.pdf


I believe that the equation for transmissibilty in 2.15.3 as it appears is correct as it is for force transmitted _due to base excitation_, rather than for force applied directly to an oscillating mass (through, for example, rotating unbalance).  (Note that the figure shows the base being excited and the section is titled Vibration Transmissibility, _Base Excitation_.)

An equation that is equivalent to the equation that appears in Section 2.15.3 of the NCEES manual appears on page 241 (equation 3.74) of the Fourth Edition of Mechanical Vibrations by S.S. Rao for base excitation.

The version of the transmissibility without the leading r^2 is for force applied directly to an oscillating mass, and an equation that is equivalent to the transmissibility without the leading r^2 appears on page 691 (equation 9.94) of the Fourth Edition of Mechanical Vibrations by S.S. Rao for force applied to an oscillating mass

Basically both the equations are correct, but are used for two different methods of exciting the mass.

Hope that helps.


----------



## PE Mechanical Reference1.2 (Oct 28, 2020)

Hey everyone,

I'm so happy to find this thread. I am studying for PE and so far I have two possible errors I found. Both are with table

1) steel pipe fraction tables 3.4.2.11 

The headloss values ( for steel, c=100) is twice the correct value. The tables I found online and if you convert the psi values to ft, they give half of the value given in the table. Anyone found the same? (I have asked NCEES for review but Don replied that review may take long time.)

2) Relative roughness values  are given as a range. Which one should we be using to get correct value. The range is big for cast iron, hence makes big difference in the answer. Please help me


----------



## Dmck (Dec 31, 2020)

2.18.2.1 Torque Requirements

T = K Fi *d *= torque*, in ft-lb*

Fi = .25Fp (reused connections)

Fi=.0Fp  (Permanent Connections)
K = torque coefficient
*d = bolt diameter, in inches*

*Torque *is has units of * "in-lb"* if* d* is plugged to the equation in terms of inches, not *ft-lb*.

Be sure to convert d or T depending on question.

I'm 3 days out from exam, and just realized this mistake with the help of a PPI solution. That would have been a horrible stupid mistake on the exam if the final answer was off by a factor of 12 from my answer and I did not understand why.


----------



## ZDG (Dec 28, 2021)

What is the process for exam questions that require material that is incorrect in the Reference Book? I am finding the same problem with steel pipe friction tables 3.4.2.11 . I am using reference book 1.4.

During the exam, will we be expected to use the incorrect table, or go into it memorizing the errata before hand?


----------



## Edgy Cheesy Graphite PE (Dec 28, 2021)

ZDG said:


> What is the process for exam questions that require material that is incorrect in the Reference Book? I am finding the same problem with steel pipe fraction tables 3.4.2.11 . I am using reference book 1.4.
> 
> During the exam, will we be expected to use the incorrect table, or go into it memorizing the errata before hand?


That's a good question. I'd be curious to know.


----------



## Slay the P.E. (Dec 28, 2021)

ZDG said:


> steel pipe friction tables 3.4.2.11 . I am using reference book 1.4.


What error do you see in this table?


----------



## ZDG (Dec 28, 2021)

Slay the P.E. said:


> What error do you see in this table?



I was looking at 8 inch and 10 inch steel pipe friction head loss per 100 ft for 1000 gpm flow. seems to be off by a factor of 2 from what I found online and in the solutions for TFS PPI 6 minute problems 3rd edition section 3 question 7. I have not checked for any other values. I read head loss as 3ft/100ft for 8inch and 1ft/100ft for 10 inch in the NCEES charts. I believe the correct numbers should be about half that (1.5ft head/100ft pipe and 0.5 ft head/100ft pipe).


It appears to be the same error that someone had in version 1.2 a year ago. I can get screenshots tomorrow if people want to verify if this is an error or if I am reading it wrong. I suppose I'll use the NCEES chat support to report this, however I'm concerned that during test day I will not know what to do if I either dont realize a mistake or know there is one and am unsure of which numbers to use.


----------



## Slay the P.E. (Dec 28, 2021)

@ZDG

For 8-inch pipe, (ID=7.981”) with Q=1000 gpm, the Hazen Williams equation with C=100 yields 3 ft head loss for a length of 100 ft, matching the value in the table.

From 3.4.2.3, Hazen-Williams for 1 foot length is:

h = 10.44 (Q^1.85)/(C^1.85*D^4.87)

If you plug in the numbers you’ll see the value in the table is correct.

This is also corroborated by the online calculator at Engineering Toolbox:


----------



## ZDG (Dec 29, 2021)

Thank You @Slay the P.E. . I was looking at this chart Pressure Loss in Steel Pipes Schedule 40


The PPI book I have uses numbers more in line with the link above. The book calls out 8 and 10 in schedule-40 steel pipe and uses 1.56 and 0.5 . "The head loss per 100 linear feet of pipe, hf, can be found using pipe friction tables. Be sure to use the water, schedule-40 steel pipe table. Looking up hf for a 10 in pipe with a flow rate of 1000gpm, it is found that hf=0.5ft/100ft" and similarly with 1.56ft for 8in. After seeing that the reference manual had errors in the past and with 2 sources showing otherwise (albiet with no rigour put into my search), I assumed the reference manual was wrong. Ill take it as a study exercise to figure out why Hazens Williams you used and the Darcy Weisbach used in the link above differ and when to use each one. 

Thank you for the insight and apologies for my misleading post. I found this old post through googling information about reference book mistakes.


----------



## Slay the P.E. (Jan 1, 2022)

ZDG said:


> Thank You @Slay the P.E. . I was looking at this chart Pressure Loss in Steel Pipes Schedule 40
> 
> 
> The PPI book I have uses numbers more in line with the link above. The book calls out 8 and 10 in schedule-40 steel pipe and uses 1.56 and 0.5 . "The head loss per 100 linear feet of pipe, hf, can be found using pipe friction tables. Be sure to use the water, schedule-40 steel pipe table. Looking up hf for a 10 in pipe with a flow rate of 1000gpm, it is found that hf=0.5ft/100ft" and similarly with 1.56ft for 8in. After seeing that the reference manual had errors in the past and with 2 sources showing otherwise (albiet with no rigour put into my search), I assumed the reference manual was wrong. Ill take it as a study exercise to figure out why Hazens Williams you used and the Darcy Weisbach used in the link above differ and when to use each one.
> ...


Ok, I see now.

As you have also noted, the table you linked uses the Darcy-Weisbach equation and the table in the reference handbook uses Hazen-Williams. One can find references recommending C=150 for Hazen-Williams in new steel pipe. Using C=150 brings the results a lot closer.

It is worth noting that the reference handbook does NOT have Darcy-Weisbach tabulated (as of version 1.4). You would have to use the actual equation.

The differences in the two approaches can be so large that the exam problem will have some unambiguous way to let you know which approach to use (for example they would give you a wall roughness or a Darcy friction factor so you would use Darcy-Weisbach since these parameters are not used in Hazen-Williams).

*EDIT*: By the way, Hazen-Williams only applies to ambient temperature water. Anything else (hot water, any other fluid etc) will have to be analyzed with Darcy-Weisbach.


----------

