Area Served
Pre-filters
After-filters
(Efficiency)
(Efficiency)
Orthopedic Surgery
30
99.97; HEPA
Filters
Medical Media
30
85
Make-up units for lab and kitchen range hood
30
-
Patient Bed Rooms
30
85
Patient care such as examination, and
30
85
treatment areas.
Pharmacy
30
85
Radiation Therapy
30
85
Radiology
30
85
Special Procedure Rooms
30
85
Spinal Card Injury Unit (SCIU)
30
85
SPD
30
85
Warehouses
30
-
(a) Notes:
(1) See Article 2.11.3 for laboratory hood filtration requirements.
(2) See Article 3.6 for BMT area.
(3) 50 mm (2 inch) thick-away filters with 15 percent efficiency are not
rated or tested as per ASHRAE standard 52.1.
(4) See VA Master Specification Section 15885, "AIR FILTERS" for filter
grades, percent, nominal efficiency and application.
(5) Design face velocity should not exceed 2.5 m/s (500 FPM) for all filters.
Preferred filter dimensions are 600 mm x 600 mm (24 inch x 24 inch). See
Specifications Section 15885, "AIR FILTERS" for recommended pressure drop.
Return and outdoor air (mixed air) shall pass through pre-filters and after-
filters.
2.3.3 CENTRAL HUMIDIFIERS
(a) Central humidifiers shall be steam manifold jacketed type with duct
mounted sensor/controller and high limit control. To protect the after-filter
from moisture, the humidifier shall be installed downstream of the after-
filter.
(b) The A/E shall consider use of chemically untreated steam source that does
not require use of facility's boiler steam, and make recommendations to VA
before proceeding with design.
2.3.4 DUCT LINING AND SOUND ATTENUATORS
(a) Field applied duct lining is not permitted in the supply air ducts.
Omission of duct lining usually requires sound attenuators in the ductwork to
meet the specified NC criteria. Perform sound analysis to ascertain the need
for sound attenuators.
(b) Air Terminal Units: Factory applied fiberglass liner, with coating to
prevent erosion and no exposed edges, is permitted in air terminal units
located downstream of the after-filters.
HVAC DESIGN MANUAL
2-8
HVAC SYSTEMS AND EQUIPMENT
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