UFC 3-420-01
25 October 2004
buildings operated on a nominal 40-hour week or on a nominal two-shift basis (either a
5- or a 7-day week), a clock or other automatic control will be installed on domestic hot-
water circulating pumps to permit operation only during periods of occupancy plus 30
minutes before and after.
M.
SECTION 608.1 General. Add after the last sentence: "Single check valves
are not considered adequate protection against back flow. Backflow preventer
applications will be tested, approved, and listed by the Foundation for Cross-Connection
Control & Hydraulic Research."
N.
SECTION 611.2 Reverse osmosis systems. Add in front of the first
sentence: "Reverse osmosis water treatment systems will be installed when water of a
higher purity than that produced by the domestic water is required, such as for de-
ionized or distilled water systems used in hospitals. A water quality analysis will be
performed and water treatment design will proceed based on that analysis. Reverse
osmosis is a general term covering equipment that can have various types of filter
elements and membranes and polishing components. The reverse osmosis membrane
selection is critical and the operating pressure depends upon the membrane selected.
Pump pressures can range from 80 to 800 psi (552 to 5516 kPa). The reverse osmosis
unit is only part of the required treatment systems, which may include pretreatment
facilities and organic filters. In some cases, booster pumps may be required for final
water distribution. Materials for piping, pumps, valves, and other components must be
carefully selected due to the corrosive nature of the high-purity water produced.
O.
[For Army and Navy projects only] Add "SECTION 613 Water softening
treatment equipment. Normally, water softening treatment equipment will be installed,
when the water analysis performed indicates a total water hardness exceeding 1.0
grains per gallon, (17 ppm) expressed as calcium carbonate. Also, water softening
usually is required at laundries, mess halls, and hospitals. Each category has its own
recommended limits for maximum hardness. Water hardness for laundries should not
exceed 2.5 grains per gallon (43 ppm) and water hardness is usually reduced to zero.
Large mess halls should have a water hardness not exceeding that provided for
laundries; whereas, hospitals can utilize water of up to 3 grains per gallon (51 ppm)
water hardness. Water softening equipment consists of a softener unit and a
regeneration brine tank utilizing common salt (NaCl) for regeneration of the softener
exchange material. Softening units can be multiple units where two or more units utilize
the same regenerating brine tank to provide for continuity of treatment during
regeneration of a softening unit.
IPC CHAPTER 7 "SANITARY DRAINAGE" SUPPLEMENTS.
A.
SECTION 712.3.1 Sump pump. Add after the last sentence: "Sump pumps
will be installed in pits below the lowest floor. Subsoil drains may discharge into this pit.
For Navy projects, provide a single pump unit where the function of the equipment is
not critical, and provide duplex pump units where the function of the equipment is critical
and also where six or more water closets are being served. When duplex pump units
A-21
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