[USMA:44069] Re: SI 10 question

[James R. Frysinger]

If you prefer, Stan, please read my 8600/s as 8600 s-1. It seems both of 
us understand each form. I of course accept the latter as being quite valid.

Jim

Stan Jakuba wrote:

You must be joking, Jim. Who would ever write 8600/s? In SI or in anything
else! Of course, you can SAY whatever you want, but the subject here is the
WRITTEN language of SI symbols.

It has been the common practice in technical literature for decades
(including in the US, UK, and similar) to write 8600 s^-1 or 8600 
min^-1, to
use your number.

If you had read the three paragraphs carefully (you had seen them many 
times
before) you'd see that, contrary to what you say, those units make 
confusion
impossible. Yes, to understand them, a bit of education helps but such
education is provided at the high-school level. But perhaps only in the 
metric countries.
Stan Jakuba


----- Original Message ----- From: "James R. Frysinger" 
<j...@metricmethods.com>
To: "U.S. Metric Association" <usma@colostate.edu>
Sent: 09 Mar 22, Sunday 14:47
Subject: [USMA:44061] Re: SI 10 question



You may wish to consult Section 8.1 of NIST SP 811. One has to be
careful with using 1/s (or s-1) for rotational rates. There is potential
confusion whether one means shaft rotations per second or angular
velocities of radians per second. So if I say, "The motor is running at
8600/s" what do I mean? Better to say, "The motor is running at a shaft
rotation rate of 8600/s" or "The motor is running at an angular velocity
of 8600 rad/s", whichever is the case. Of course those differ by a
factor of 2 pi.

Jim

Stan Jakuba wrote:

FREQUENCY



There are three kinds of frequencies, and correspondingly three 
different units:



-- Angular Frequency, commonly called angular velocity. Its unit is 
rad/s.



-- Cycle Frequency. It is defined as the number of periodic events 
(cycles) per second. This unit was given the name hertz (in honor of 
the German scientist), symbol Hz.



-- Rotational Frequency, commonly called speed of rotation or simply 
speed. Its unit is s­-1 optionally written also as 1/s.



Note: The units of the cycle frequency and rotational frequency are 
sometimes, and incorrectly, written as c/s or cps, and r/s or rps, 
respectively. These symbols could be misunderstood in non-English 
speaking countries. Furthermore, cycles and revolutions are not 
units; if used, these words should be spelled out or clearly 
abbreviated such as rev./s, rev./min., etc.

Stan Jakuba



----- Original Message ----- From: "James R. Frysinger" 
<j...@metricmethods.com>
To: <si...@listserv.ieee.org>
Sent: 09 Mar 14, Saturday 22:25
Subject: Re: [SI] SI 10 question


Paul,

Rotational speeds are usually given as revolutions per second or 
revolutions per minute. To that point, one would want to list both 
r/s and r/min. Some folks use Hz instead of r/s, especially for 
shaft rotational rates since that is a periodic function (angular 
position as a function of time).

In my physics classes I required my students to use r/min rather 
than rpm.

Jim

Paul Trusten wrote:
Bruce, this is revolutionary! (grin).  I never thought of 
symbolizing that, and it should be symbolized, since we avoid KPH 
in favor of the correct km/h.

Would it be more elegant, to use the base unit of time, and make 
the quantity revolutions per second, proposed symbol r/s?  That 
would make, let's say, 5000 r/min change to about 80 r/s.  I think 
perhaps not, since r/min is an established unit.

Paul

----- Original Message ----- From: "Bruce Barrow" 
<bbarr...@verizon.net>
To: <si...@listserv.ieee.org>
Sent: 14 March, 2009 20:19
Subject: Re: [SI] SI 10 question


Mr. Bowman,

You are coming up with some very good questions!  Our IEEE Std on 
Unit
Symbols, Std 260.1-2004, lists r/min as the appropriate unit 
symbol, and
includes as a note, "Although use of rpm as an abbreviation is 
common, it
should not be used as a symbol."  I'm not sure ordinary mortals, 
as opposed
to members of selected standards committees, understand the 
difference.

I am proposing that our revised SI10 include only "r/min".

Bruce

----- Original Message ----- From: "Lyle Bowman" 
<jbfoo...@comcast.net>
To: "Bruce Barrow" <bbarr...@verizon.net>
Sent: Thursday, March 12, 2009 1:17 PM
Subject: FW: SI 10 question


Mr. Barrow,

Jim may have forwarded my question re 'rpm' (shown below) to you 
already.
Had I known you were the person more directly responsible for the 
SI 10
standard, I would have sent the request directly to you.

Lyle Bowman.

------ Forwarded Message
From: Lyle Bowman <jbfoo...@comcast.net>
Date: Tue, 10 Mar 2009 15:12:50 -0700
To: "James R. Frysinger" <j...@metricmethods.com>
Conversation: SI 10 question
Subject: FW: SI 10 question

Jim,

Thanks for the prompt response to my question.

Perhaps, you can help me with another question also. In Table A.1 
of the
SI
10  standard (Page 36), the 'to convert from' column lists 
'revolutions
per
minute (rpm)'. The previous E 380 standard listed both rpm and 
r/min, and
I
note that the BIPM SI Brochure also lists both of these. The ASTM 
Form and
Style for ASTM Standards document lists just r/min. Since the SI 
10 has
been
my 'bible' for revising the some 35 ASTM standards I'm 
responsible for,
I've
used 'rpm' in those revisions.

My question is why does the SI 10 standard list only 'rpm'?

I've conjectured that 'rpm' was preferred because it definitely 
would not
be
mistaken for a SI unit, but 'r/min' might possibly be.

Regards,

Lyle.

------ Forwarded Message
From: "James R. Frysinger" <j...@metricmethods.com>
Date: Tue, 10 Mar 2009 16:02:43 -0500
To: Lyle Bowman <jbfoo...@comcast.net>
Cc: <d.rin...@ieee.org>, <j.frysin...@ieee.org>, 
<b.bar...@ieee.org>,
<m.kipn...@ieee.org>, <r.ge...@ieee.org>, <k.breitfel...@ieee.org>,
<y.hos...@ieee.org>
Subject: Re: SI 10 question

Dear Mr. Bowman,

I am the chair of a committee, some members of which represent 
the IEEE
portion of the IEEE/ASTM Joint Committee for Maintaining SI 10. Your
message has been forwarded to me for a reply.

Standard practice in the U.S. is to use a space instead of a 
hyphen when
unit symbols are used, whether the expression is in noun ("a 
width of 35
mm") or adjectival form ("35 mm film"). That would comply with the
normative statements of IEEE/ASTM SI 10 as well as NIST SP 811. 
Further,
and importantly, it complies with Section 5.3.3 of the SI 
Brochure (8th
ed.)

Your suggestion to make an explicit statement in SI 10 regarding
application of this practice to the adjectival form is noted and 
will be
considered for the revision (update) now in progress. Thank you 
for that
thought!

You may have noticed that SP 811 says the hyphen "is acceptable" 
(but
not required) in adjectival forms when the unit name is spelled out
("35-millimeter film"). Personally, I prefer using a space there as
well; the movement in language is generally toward economy of
punctuation, except as needed to avoid ambiguity.

Thank you very much for your interest in SI 10. Most certainly, 
we are
pleased to hear that you are working towards improved metrication of
ASTM standards. If you have any other questions, please do not 
hesitate
to write or call.

regards,
James R. Frysinger (Jim)
Chair, Standards Coordinating Committee 14
IEEE Standards Association

d.rin...@ieee.org wrote:

Jim,

Please see the communication (below), regarding SI 10.

Thanks,
****************************************************************
David L. Ringle
Manager - IEEE-SA Governance, Policy & Procedures
IEEE Standards Activities Department
445 Hoes Lane
Piscataway, NJ  08854-4141 USA
TEL: +1 732 562 3806
FAX: +1 732 875 0524
d.rin...@ieee.org
****************************************************************

March 4, 2009

I'm an ASTM member and have been given the task of revising the
measurement units in many ASTM standards to SI units.

The IEEE/ASTM SI 10-2002 standard has been my primary reference 
in doing
this task.

There's one question that I haven't been able to resolve, and 
that is
whether to place a hyphen between a number and an SI unit when the
combination is used in an adjectival sense. My SI 10 reference 
(Section
3.5.1, item d)) says to leave a space between a 'numerical value 
and a
unit symbol', and does not comment on the possible adjectival 
usage.

An earlier ASTM E 380 SI Standard says to hyphenate when the 
combination
is used in an adjectival sense, and the current NIST Special 
Publication
811 (SP 811) says specifically not to hyphenate in that situation.

Assuming that it's also the intention of the IEEE/ASTM 10-2002 
standard
to not hyphenate when a combination of a numerical value and a unit
symbol is used in an adjectival sense, I'd recommend that a 
specific
statement to that effect be included in the standard.

I'd appreciate being informed if my above assumption is incorrect.

Sincerely,
Lyle Bowman
728 Montecillo Road
San Rafael, CA  96904-3136

Phone: 415-479-3004

Email: jbfoo...@comcast.net

--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030

(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108


------ End of Forwarded Message

------ End of Forwarded Message









--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030

(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108





--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030

(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108






--
James R. Frysinger
632 Stony Point Mountain Road
Doyle, TN 38559-3030

(C) 931.212.0267
(H) 931.657.3107
(F) 931.657.3108