3.22.4.6 AIR DISTRIBUTION: The air distribution system for S/KI TB
isolation rooms and TB treatment rooms shall be designed to ensure that
the air distribution patterns have the following characteristics:
(a) The supply air flows towards the patient beds or treatment tables and
not towards corridors or adjacent areas.
(b) The exhaust air registers are located close to the patient.
(c) CDC requires that the negative pressure in the room should be
monitored daily while the room is being used for TB isolation. This could
be as simple as periodic measurement of the direction of air flow
direction using simple procedures such as flutter strips or small amounts
of smoke, or can utilize more elaborate pressure sensors. As a minimum we
recommend that the exhaust fan be monitored with an airflow switch such
that alarms are sent to a central location, such as the engineering
control center (ECC) or nurses station if the fan stops. However the
monitoring is accomplished, it should be documented regularly with records
maintained for a reasonable length of time. VAMC staff should use their
judgment to determine if more elaborate monitoring systems are required
for their application.
3.22.5 AIR HANDLING SYSTEMS (EXISTING AND NEW FACILITIES)
3.22.5.1 EXISTING FACILITIES
3.22.5.1.1 All AIR SYSTEMS: The S/KI TB isolation rooms and TB treatment
rooms should be located in existing facilities only where "all air" types
of HVAC systems are installed, provided these systems operate 24 hours a
day including the following:
(a) The existing HVAC systems have adequate spare capacity to meet the
increased demand for the supply and outdoor air volumes. Components, such
as supply air fan, motor, cooling and heating coils, and the elements of
the air distribution system, should be closely reviewed and revised, as
necessary, to meet the new duty conditions.
(b) Individual room temperature control is required for each patient room
and treatment room. For the ambulatory care areas (emergency rooms and
waiting areas etc.), individual room temperature control is desirable, but
not mandatory.
3.22.5.1.2 FAN COIL UNITS: The S/KI TB isolation rooms and TB treatment
rooms and waiting areas for S/KI TB patients shall not be located in areas
utilizing fan coil units because of the following reasons:
(a) Recirculation of room air will make it difficult to control droplet
nuclei.
(b) The periodic removal and replacement of air filters, installed in fan
coil units, could be an additional source of contamination. These filters
are inefficient for preventing the spread of droplet nuclei.
(c) With fan coil units, the quantity of outdoor air is small, estimated
only to meet the minimum ventilation and/or toilet exhaust needs. The
feasibility and cost of increasing the outdoor air quantity, to meet the
HVAC DESIGN MANUAL
3-29
HVAC REQUIREMENTS FOR OCCUPIED AREAS
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