06-06
capacity due to possibility of reentry of air from cooling towers,
air cooled condensers, etc. The bottom of the intake louvers shall be
located as high as possible but not less than three feet above ground
level. Maximum louver velocity shall not exceed 4 m/s (750 feet per
minute) through the free area of 35 percent. For drainable louvers,
maximum velocity of 5 m/s (1,000 feet per minute) and 45 percent free
area is acceptable.
F. MISCELLANEOUS: At medical centers where cottonwood trees, or similar
types, are likely to interfere with operation of air intakes for air
handling units, cooling towers, or air cooled condensers, provide
easily cleanable screens or roughing filters at the air inlets.
8. SEISMIC REQUIREMENTS
8.1 GENERAL
A. Earthquake-resistive design shall comply with the requirements of
Construction Standard CD-54, Natural Disaster Resistive Design (Non-
Structural), latest edition of VA Handbook H-18-8, Seismic Design
Requirements, and the Uniform Building Code (UBC) published by
International Conference of Building Officials (ICBO).
B. Earthquake-resistive design for HVAC equipment shall be provided
where `Z' value is 0.10 or greater and for piping and ductwork where
`Z' value is 0.20 or greater. The `Z' values for VA sites are listed
in VA Handbook H-18-8. These values must be verified with VA for a
specific project before proceeding with the design.
C. HVAC equipment, certain ductwork, and piping shall be braced in
accordance with the most current edition of Seismic Restraint Manual
Guidelines for Mechanical Systems (SMACNA) and National Uniform
Seismic Installation Guidelines (NUSIG).
D. Unless otherwise shown by SMACNA or NUSIG, provide required details
and structural calculations to completely address seismic bracing
requirements. See paragraph 8.4 "CALCULATIONS".
E. SMACNA does not cover all conditions such as, providing bracing
details for seismic restraints of equipment or details of flexible
joints when crossing seismic or expansion joints, or bracing of in-
line equipment, etc. Also be careful in using SMACNA details where
`Z' value is more than 0.40, as these details may not apply.
F. Coordinate earthquake-resistive design with the project Professional
Structural Engineer for appropriateness and soundness.
G. Both, SMACNA and NUSIG list conditions under which seismic bracing
may be omitted. However, a design professional may revoke these
omissions on an individual project basis.
29
Previous Page
