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Pump Safety: Flirting With Disaster

I just finished reading your article (Pump Safety: Flirting With Disaster, pp. 67–70, December 2016) and want to indicate the following:

In the third example, the text said that the HBEP/HSO is 0.7, but in the formula, 0.75, (0.75–1) is written as the divisor. With 0.7, the relation QSO/QBEP is 0.166666, which is less than the stated 0.20.

By the way, I found the article very interesting.

Ernesto Calderón
Head of Design Process Engineering, Techint 

Author’s response

Mr. Calderón is correct. He must have read the article very carefully to glean that, in Example 3, I stated that HBEP/HSO was 0.7, but inserted a value of 0.75 into the calculation. With the correct value (0.7), you get a
QSO/QBEP ratio of 0.166666, which is lower than the value of 0.20 that I stated.

 We need to thank Mr. Calderon for identifying the error in my calculations and then calculating the correct value for the QSO/QBEP ratio.

Robert Perez

Editor’s note: The correction to Example 3 as stated above has been included in the online version of this article:


Re-Establishing Course 

Your article in the November 2016 edition of Chemical Engineering was excellent (Re-Establishing Course, pp 67–70; There is so much pertinent information, very to the point and written from your [the authors] personal experience — not by some person just “imagining” what the situation of having to re-establish course would be like. There is nothing like first-hand knowledge to give weight to a story. 

I am retired and not in a position of looking for employment, although I have had a few part- and full-time jobs that needed my area of expertise. I read the story because it sounded interesting and the further I got, the more it made an impression on me. If I were in a position of needed to “start over,” I would have your story as my main guide. Thank you very much. 

Brian T. Bender
Napa, California