| (a) The following provides policy guidelines for the
use of US customary units and metric (SI) units. Throughout this chapter,
metric (SI) units are identified and placed in parentheses after the
US customary units in the text and any associated exhibits.
(b) There are two rationales when converting between
US customary units and metric (SI) units:
(1) Soft conversions--A soft conversion is an exact
conversion.
(A) Example: 200,000 Btu/hr = 58.56208 kW
(B) Example: 120 gallons = 454.24944 liters
(2) Hard conversions--A hard conversion is simply performing
a soft conversion and then rounding off within the intended specific
range.
(A) Example: 200,000 Btu/hr = 58.6 kW
(B) Example: 120 gallons = 454 liters
(c) Repairs and alterations, when performed, shall
be to the specified units used in the original code of construction.
If the original units are US customary units, then the repair or alteration
shall be to US customary units, and if the original units are metric
(SI) units, then the repair or alteration shall be to the metric (SI)
units. The selected units shall be used consistently throughout each
repair or alteration and all aspects of the work required (i.e. materials,
design, procedures, testing, documentation and stamping).
(d) The following procedure shall be used when converting
between US customary units and metric (SI) units.
(1) All conversions will be done using a soft conversion;
(2) Soft conversions will be reviewed for accuracy;
(3) Depending upon a specified value in this chapter,
an appropriate degree of precision shall be identified; and
(4) Rounding up or down may apply to each conversion
to determine the degree of precision needed for each application.
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