size of pipe to select. One example is table 7-7;
it shows storm drain sizes. Remember that this
table is to be used only as a guide when estimating
for storm drainage, as different areas have
different intensities of rainstorms.
Another method for sizing building storm
drains is to provide 1 square inch of pipe cross-
sectional area for each 100 square feet of roof
area. This method is easy to remember: 1 square
inch for 100 square feet. (However, it is not as
accurate as using table 7-7.) Using this method,
you can prepare a table similar to table 7-8. Show
the diameter in the first column; then the radius
(which is one-half the diameter); then the square
of the radius; then the cross-sectional area, which
is pi (3.14) times the radius squared. Since each
square inch may take 100 square feet of roof,
move the decimal of the square inches over two
places to the left (which is multiplying by 100) to
get the area of the roof that may be drained to
the pipe. As you can see by comparing table 7-7
with table 7-8, the second method is much more
conservative.
Sizing Site Storm Sewers
While rules of thumb such as those just
described are used to size building storm drains,
different procedures are used to size the storm
sewers that carry the runoff from the building site
and surrounding land areas. The design and
sizing of storm drains are provided by engineers.
It is not necessary that the UT understand the
factors that contribute to the design. Therefore,
the information is not included here.
WATER SUPPLY SYSTEMS
After the pipe runs and fittings are located on
a print or drawing, the size, quantity, and
joining requirements of the pipe must be deter-
mined. When a plumbing print is available for the
job, it will contain this information. If there is
no blueprint, you must determine these require-
ments yourself. The quantity of pipe required and
the number and types of fittings you intend to use
Table 7-8.—Fixture Demand
Table 7-7.—Size of Horizontal Building Storm Drains and Building Storm Sewers
7-10
|
|
