James,
I believe you'll find your answer in section 1.6.1.4 (in the '13
and '16 editions) which reads:
1.6.1.4 If a value for measurement as given in this standard is
followed by an equivalent value in other units, the first stated
shall be regarded as the requirement.
Also, the '16 edition contains the following paragraph:
1.6.3* Some dimensions used in this standard are exact and some are
not. Nominal dimension are often used, such as the
dimensions used for pipe sizes. The metric equivalent shown in this
standard might not be an exact conversion to the SI unit, but the
nominal metric equivalent is typically used or a reasonably
equivalent value or approximate conversion is used. It shall be
acceptable to use the exact conversion or the conversions stated in
the standard, even though they might not be exact.
And the annex goes on to say:
A.1.6.3 Some dimensions used in this standard require a tight
precision and others do not. For example, when performing
hydraulic calculations more precision is required than when
specifying a nominal dimension. An example is pipe sizes, where we
typically refer to a nominal diameter rather than the exact
diameter. The metric equivalents also have a set of generally
accepted nominal measurements, and they are not a precise conversion
from the “English Unit” nominal dimension. Throughout the standard
the generally accepted nominal pipe sizes have been used. For
example 1 in. pipe = 25 mm, 11⁄4 in. pipe = 32 mm, 11⁄2 in. pipe =
40 mm, and so forth. In other cases, rounding is used and the number
of significant digits taken into account. For example, a 30 ft
ceiling would be 9.144 m. This implies a level of precision that is
higher than used for the original dimension, and a conversion to 9.1
m or even 9 m is more appropriate. Another example is that in the
standard, 1 in. has been converted to 25 mm and not 25.4 mm, 2 in.
to 50 mm, 6 in. to 150 mm, and so forth. Finally, locally available
material can have different characteristics in countries that use
metric units than are typically found in the United States. Examples
are things like standard door or window sizes, rack dimensions, and
so forth. In these cases an approximate conversion can also be
used. Where approximate conversions have been used, it is acceptable
for a designer or installer to use an exact conversion rather than
the approximate conversion used in the standard.
I wasn't a part of it however memory serves to tell me there was a
substantial metric conversion task group for this cycle.
*Ken Wagoner, SET
*Parsley Consulting***
*350 West 9th Avenue, Suite 206
*Escondido, California 92025
*****Phone 760-745-6181*
Visit our website <http://www.parsleyconsulting.com/> ***
On 04/20/2016 3:42 PM, James Crawford wrote:
NFPA #13 (2013) section 8.12.3.2 minimum distance between ESFR heads not
less than 8’-0” or (2.4 m)
We are looking at a project and the ESFR heads are space at 2.4 meters apart
and this seems to meet code, but 2.4 m equals 7’-10 ½”.
Is this an over site by NFPA or are you allowed to be less than 8’-0” or
should it be 2.439 m and was just missed in the conversion.
This would be the same for the obstruction rule 1’-0” is 0.305 m not 0.3 m
and 2’-0” is 0.610 m not 0.60 m
Just wondering.
Thank you
James Crawford
Phaser Fire Protection Ltd.
Phone 604-888-0318
Fax 604-888-4732
Cel 604-790-0938
Email [email protected]
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