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Darby R., "chemical Engineering Fluid Mechanics", 2nd Editio


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#1 sheiko

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Posted 30 November 2008 - 05:11 PM

FYI, I have attached the latest Errata sheet for the 2nd Edition of the "Chemical Engineering Fluid Mechanics" handbook from Ron Darby.

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#2 Art Montemayor

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Posted 30 November 2008 - 06:20 PM

Sheiko:

Thank you for sharing this important information with all of us.

I have noted the many errata in my copy.



#3 katmar

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Posted 01 December 2008 - 01:46 AM

Thanks Sheiko


#4 sheiko

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Posted 16 February 2009 - 02:32 PM

I have attached the latest Errata for the book, FYI.

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#5 Art Montemayor

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Posted 16 February 2009 - 08:36 PM


Sheiko:

Thanks once again for sharing any errata notices from Ron Darby.

I note that compared with the prior listing you issued on the 2nd Edition, this list only has ONE additional, new errata:

Page 267: Equation (9-1) should be rho = PM/RT

Everything else is the same in both listings. However, I still can not understand the following:

Page 210: Mitered weld bends - there is NO 45 degree: 2 welds

Page 466: Equation (15-62) ........the last term IS vm already. There is NO Vm

Does any body else have any other bugs or errata on this book?


#6 katmar

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Posted 19 February 2009 - 05:43 AM

There is an additional error on Page 210 of the second edition. In the same way that the (L/D)eq values for 2 weld and 3 weld Mitered 90 deg Elbows were given per weld instead of per elbow the Ki values are also per weld. For a 2 weld mitered 90 deg elbow Ki should be 0.136 and for a 3 weld elbow it should be 0.105. The Kd values are not affected by this error.

Strangely, the values for 45 degree elbows only have the error in the (L/D)eq value and not in the Ki value.

Please note that these corrections are my own opinions and are not official.

Art, I am confused by your statement that there is no 2 weld 45 degree mitered bend. There is in my copy. Are you working with the first edition? I believe that was even worse than the second edition in terms of typographical errors. Pity such a good book is marred by these basic production errors. I have attached a scan of the uncorrected version of page 210 from my copy.

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#7 Art Montemayor

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Posted 20 February 2009 - 10:49 AM


Harvey:

Thank you very much for your valuable contribution. Yes, I'm working with the 1st and 2nd Printings of the 2nd edition. Apparently, the editor and printer can't get it straight. It is a downright shame to have these pitiful and totally avoidable errors in such a great book. Ron Darby must be having fits up in College Station.

Table 7.3 on page 210 is particularly a serious blow to this book since it is the backbone of data for Darby's 3-K Method - which Ken has pioneered. Not only is the table badly laid out without any reference guidelines to horizontally orient you across the page, but the organization is terrible. The main category of "Elbows" is listed as 90o, 45o, and 180o. WELL, there is no such thing as a 180o elbow! There is a 180o RETURN - which is certainly not an "elblow".

The listing for valves also does not distinguish between up-flow and down-flow for globe valves and, especially, angle valves. This is a pity because this should be the "central bank" for finding the Ki and Kd for all kinds of piping configurations. There should be no better authoritative source for 3-K calculation instructions.


#8 sheiko

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Posted 21 February 2009 - 04:55 AM

QUOTE (katmar @ Feb 19 2009, 11:43 AM) <{POST_SNAPBACK}>
There is an additional error on Page 210 of the second edition. In the same way that the (L/D)eq values for 2 weld and 3 weld Mitered 90 deg Elbows were given per weld instead of per elbow the Ki values are also per weld. For a 2 weld mitered 90 deg elbow Ki should be 0.136 and for a 3 weld elbow it should be 0.105. The Kd values are not affected by this error.

Strangely, the values for 45 degree elbows only have the error in the (L/D)eq value and not in the Ki value.

Please note that these corrections are my own opinions and are not official.


Harvey,

I am a bit confused about the comment regarding the mitered bends in table 7-3 - do you mean that the values of all the K's in the table should be "per weld", so that for a "3 weld fitting" for example, all of the K's should be multiplied by 3?

#9 katmar

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Posted 21 February 2009 - 02:24 PM

The (L/D)eq values as they were printed in the 2nd Ed were per weld instead of per elbow. For example, for a 2-weld elbow the errata sheet that you posted increased the (L/D)eq value from 15 to 30. This is a factor of 2 because there are 2 welds. Similarly the errata sheet corrected the (L/D)eq value for a 3-weld elbow from 8 to 24 - a factor of 3 because there are three welds.

The corrections I posted above are on the same logic - increase the Ki values by the same factor as the number of welds. I have compared the calculated K values with the Hooper 2-K method and with Crane 410 page A29 to convince myself of this.

This means that you can use the corrected values to calculate the K values for an elbow without again multiplying by the number of welds.

#10 sheiko

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Posted 23 February 2009 - 04:17 PM

Dear Harvey,

In the same way that for a 2 weld mitered 90 deg elbow Ki should be 0.136 and for a 3 weld elbow it should be 0.105, shall we consider that for 2 weld mitered 45 deg elbow Ki should be 0.104 instead of 0.052?

#11 katmar

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Posted 24 February 2009 - 12:45 PM

QUOTE
shall we consider that for 2 weld mitered 45 deg elbow Ki should be 0.104 instead of 0.052?


See my post of Feb 19 above.

If you made Ki 0.104 it would make the resistance of a 2-weld elbow more than that for a 1-weld elbow and that would clearly be wrong. As I said before, I believe the Ki's are correct for the 45 degree elbows, even though the (L/D)eq was wrong.

#12 sheiko

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Posted 24 February 2009 - 04:38 PM

Dear Art,

QUOTE (Art Montemayor @ Feb 20 2009, 04:49 PM) <{POST_SNAPBACK}>
The main category of "Elbows" is listed as 90o, 45o, and 180o. WELL, there is no such thing as a 180o elbow! There is a 180o RETURN - which is certainly not an "elblow".

In the 2nd. edition of the book, the table says it is a "close return bend". I think that should be clear.

QUOTE (Art Montemayor @ Feb 20 2009, 04:49 PM) <{POST_SNAPBACK}>
The listing for valves also does not distinguish between up-flow and down-flow for globe valves and, especially, angle valves. This is a pity because this should be the "central bank" for finding the Ki and Kd for all kinds of piping configurations. There should be no better authoritative source for 3-K calculation instructions.

I don't see why there should be a difference between "up-flow" and "down-flow" for globe valves, as long as the flow is in the right direction thru the valve. No?

#13 sheiko

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Posted 26 February 2009 - 01:47 PM

FYI, attached is the latest errata sheet.

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#14 Jared2000

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Posted 26 May 2011 - 10:08 AM

FYI, attached is the latest errata sheet.


Sheiko,

I believe there may be an error in the Errata. Shouldn't the second correction for page 212 be "3rd and 4th Eqns these Eqns apply for Theta>45 degrees".

It just seems weird for it to be the 2nd and 4th equations.

Jared

#15 sheiko

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Posted 29 May 2011 - 11:29 AM

Sheiko,

I believe there may be an error in the Errata. Shouldn't the second correction for page 212 be "3rd and 4th Eqns these Eqns apply for Theta>45 degrees".

It just seems weird for it to be the 2nd and 4th equations.

Jared


Yes you are right. The corrections applies to the 3rd and 4th equations. No doubt given the formulae.




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