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RPM or Rev/Min?
3

RPM or Rev/Min?

RPM or Rev/Min?

(OP)
Which is preferred on a plot of something against engine speed?  Are they interchangeable?  Is it simply preference?  Or is there good argument for one over the other?

- Steve

RE: RPM or Rev/Min?

"rpm" is fewer letters and is universally recognized.  "Rev/min" could easily apply to Microsoft and their revision history.

David

RE: RPM or Rev/Min?

rpm is specific to English and so not preferred from a global perspective.  ISO 1000 shows the SI unit for rotational frequency to be s-1, it recognizes min-1, and has the following note:

The designations "revolutions per minute" (r/min) and "revolutions per second" (r/s) are widely used for rotational frequency in specifications on rotational machinery. (See IEC 27-1.)

RE: RPM or Rev/Min?

(OP)
David, it could also describe the politics of some countries...

My audience is truly international, but we impose (US) English on them.

The question arose because during an overhaul of some software I'm responsible for, the US reviewer asked me to change all "rev/min" labels to "RPM".

- Steve

RE: RPM or Rev/Min?

I use "rpm" (lowercase) and have never had it not recognised by any customer in the world. Coming from a general acoustics and vibration background, I mentally convert it to Hz or rad/s. Any calcs are done in Hz or rad/s so in my manifesto rpm, RPM, or rev/min would not exist.

M

--
Dr Michael F Platten

RE: RPM or Rev/Min?

What does the rev counter in your car (if it has one) say?

It is one of those things like the 3 on an analog watch - you see it every day but don't really remember what it says.

RE: RPM or Rev/Min?

(OP)
I don't have a car.

- Steve

RE: RPM or Rev/Min?

xwb,

It says 1/min, which is accepted within SI, so that it needn't be translated for every language in the world.

RE: RPM or Rev/Min?

(OP)
Similarly, my analog watch does not have a 3 on it, just day and date where the 3 should be winky smile

I do often see tr/min and U/min in my work though.

- Steve

RE: RPM or Rev/Min?

U/min I know (German), but tr/min I've never seen. What would it be short for?

Benta.
 

RE: RPM or Rev/Min?

I would be more worried about the readers ability to comprehend the rest of the write up, if they can't comprehend rpm or any other similar terms that are in use for ages!


 

Rafiq Bulsara
http://www.srengineersct.com

RE: RPM or Rev/Min?

Quote (CoryPad):

rpm is specific to English and so not preferred from a global perspective.  ISO 1000 shows the SI unit for rotational frequency to be s-1, it recognizes min-1, and has the following note:

   I realize that revolutions are not real units of measure, but neither are radians, or degrees for that matter.  I would take RPM over that, any time.  
 

               JHG

RE: RPM or Rev/Min?

Once upon a time in the dim and distant I was asked to rewrite part of a report to change the first occurrence of rpm to revolutions per minute (rpm). When I pointed out that all of the report's intended readers would understand the meaning of "rpm" to my Japanses mentor, he replied along the lines of "not everyone understands abreviations Bennett-san". It turns out neither he or his boss understood the term, as neither of them were engineers.

RE: RPM or Rev/Min?

Had neither of them ever purchased an LP recording on vinyl?  My mom had a high school education but she knew that 45 rpm rotated faster than 33-1/3 rpm.

David

RE: RPM or Rev/Min?

It isn't a matter of education level.  Phonographs in Japan wouldn't have the rotation speed switch labeled with the English letters rpm.

RE: RPM or Rev/Min?


Benta,

tr/min = turns/min?

RE: RPM or Rev/Min?

(OP)
"tours" according to my French colleague.

- Steve

RE: RPM or Rev/Min?

Quote:zdas04
..."Rev/min" could easily apply to Microsoft and their revision history.

Thank you -- my best loll in a long while.  The second l stands for "loudly."

...or it could be revisions/min in the kingdom of design engineering.  Or as I like to refer to these so-called revisions as, "revelations."

cheers

RE: RPM or Rev/Min?

IEEE SI 10 shows the plane angle symbol for revolution or turn units as r and the value in SI units r=2 pi rad.  Also it shows to convert from rpm to radian per second (rad/s) multiply by 2 pi/60.  Minitue is abreviated as min.  Thus consider r/min for rpm.

RE: RPM or Rev/Min?

IEEE 100 agrees with r/min.

RE: RPM or Rev/Min?

Fighting culture with obscure standards (that too French!) has no hope of success.

In North America and South Asia, r/min user would have more explaining to do than rpm.

Rafiq Bulsara
http://www.srengineersct.com

RE: RPM or Rev/Min?

Quote:

I realize that revolutions are not real units of measure, but neither are radians, or degrees for that matter.  I would take RPM over that, any time.

I have to take issue with that.  These are all "real", they all have a perfectly logical definition.  However, only radians are dimensionless, which you will find out very quickly if you are solving equations using angles. (Yep, just finished finals, and yep, had to be careful with that one.) Of course, I hate it when a pre-derived formula calls for an angle and only gives the correct value when you input degrees without explicitly telling you to do so.

For this same reason, the 1/rev placard on my tachometer drives me nuts.  Its not that I don't know what they're implying, it that what they're implying is not what they're actually saying.

RE: RPM or Rev/Min?

Why isn't it R'spm?

rmw

RE: RPM or Rev/Min?

I've always been a little bothered by the use of RPMs in the automotive world.  Revolution(s?) per minutes?  How many minutes are we talking about anyways?

RE: RPM or Rev/Min?

It's the revolutions that are plural, the minute is singular.  How is it any different than any other rate unit like miles per hour or gallons per second?

RE: RPM or Rev/Min?

Or runs batted in.

rmw

RE: RPM or Rev/Min?

Quote (dgallup ):

...like miles per hour...

I thought it was miles-pen-hour because that is how the instructor pronounced it at least 70 times during a class in driving a 1-1/2 ton ruck for the army in basic training.

Permit me to digress?  A once upon a time co-worker used to complain that his mother would insist that he wash his hands with hot soap and water.  (Surely?) she must have said, "hot soapy water."  Some quirk of the mind made me think of this from reading Busa's plural minutes comment.

RE: RPM or Rev/Min?

Perhpas to clarify, it the plot should be multiplied by 360 and read "degrees per second, dps, or deg/sec."

Or to very precies it should be multipled by 6.28 and read radians/second?

Or, the plot should read hz/2*pi /sec?

Personally, rpm on a plot, and rev/min in a computation would work for me.


 

RE: RPM or Rev/Min?

Other languages often adopt english terms (just as english adopts theirs).  If there is an issue, just footnote it or hyperlink it to the wikipedia article.

Matt Lorono
Lorono's SolidWorks Resources & SolidWorks Legion

&

RE: RPM or Rev/Min?

I have two non American or British racing friends (really, I do)...One is a French Canadian the other Japanese.  Both are in their late 50's, early 60's I'm guessing.  I mentioned this thread since they both speak fair English.  Both are well traveled men and "rpm" seems the only thing they have ever used...Ever!  Man, if a French speaking Canadian is willing to go with "rpm"...That's just gotta be definitive!

Rod

RE: RPM or Rev/Min?

I would do what the Jerries do, use s^-1.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

RE: RPM or Rev/Min?

Abbreviation, SI label or acronym?
Somewhere in the dim past, I was taught that it was courteous to write out in full, capitalized, the first use of an acronym.
The correct initialization or acronym treatment of Revolutions Per Minute is RPM. It may be abbreviated as rpm, and SI is SI.
 

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: RPM or Rev/Min?

waross,
A few years ago a new magazine about PDA's was published.  I bought a copy to learn but to no avail because they used abbreviations and/or acronyms galore without writng out in full the descriptive words symbolised by the letters after each first use of these "modern" symbolisms.  It was pretty much unintelligible for anyone not on the cutting edge of Personal Digital Assistant devices.

An acronym is an abbreviation but an abbreviation is not always an acronym.  For example, RPM is not an acronym.

ac•ro•nym  [ak-ruh-nim]  Show IPA
–noun
1.
a word formed from the initial letters or groups of letters of words in a set phrase or series of words, as Wac from Women's Army Corps, OPEC from Organization of Petroleum Exporting Countries, or loran from long-range navigation.
2.
an acrostic.
a•cros•tic  [uh-kraw-stik, uh-kros-tik]  Show IPA
–noun
1.
a series of lines or verses in which the first, last, or other particular letters when taken in order spell out a word, phrase, etc.
 

RE: RPM or Rev/Min?

(OP)
Like LOMBARD from the 1980's.

- Steve

RE: RPM or Rev/Min?

Interestingly, most of the world's languages do not have any abbreviation for 'revolutions per minute'. In fact, very few languages are using abbreviations to the extent of English language.
Cheers,
gr2vessels

RE: RPM or Rev/Min?

Where I work we have 2 maybe 3 pages of abbreviaions and acronyms.  It can be helpful but also disconcerting.

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