NOTE: Negative Air Pressure Systems are typically
required only for projects using powered floor
sanding or abrasive blasting techniques. Both
techniques may have application for historical
restoration, but are not typically used as lead
hazard abatement techniques. Remove the following
two paragraphs if negative air pressure systems are
not necessary for the project.
**************************************************************************
1.12.2.1
Minimum Requirements
Work shall not proceed in the area until containment is set up and HEPA
filtration systems are in place. The negative air pressure system shall
meet the requirements of ANSI Z9.2 including approved HEPA filters per UL
586. Negative air pressure equipment shall be equipped with new HEPA
filters, and shall be sufficient to maintain a minimum pressure
differential of minus 0.005 kPa 0.02 inch of water column relative to
adjacent, unsealed areas. Negative air pressure system minimum
requirements are listed below:
a.
The unit shall be capable of delivering its rated volume of air
with a clean first stage filter, an intermediate filter and a
primary HEPA filter in place.
b.
The HEPA filter shall be certified as being capable of trapping
and retaining mono-dispersed particles as small as 0.3 micrometers
at a minimum efficiency of 99.97 percent.
c.
The unit shall be capable of continuing to deliver no less than 70
percent of rated capacity when the HEPA filter is 70 percent full
or measures 0.625 kPa 2.5 inches of water static pressure
differential on a magnehelic gauge.
d.
The unit shall be equipped with a manometer-type negative pressure
differential monitor with minor scale division of 0.005 kPa 0.02
inch of water and accuracy within plus or minus 1.0 percent. The
manometer shall be calibrated daily as recommended by the
manufacturer.
e.
The unit shall be equipped with a means for the operator to easily
interpret the readings in terms of the volumetric flow rate of air
per minute moving through the machine at any given moment.
f.
The unit shall be equipped with an electronic mechanism that
automatically shuts the machine off in the event of a filter
breach or absence of a filter.
g.
The unit shall be equipped with an audible horn that sounds an
alarm when the machine has shut itself off.
h.
The unit shall be equipped with an automatic safety mechanism that
prevents a worker from improperly inserting the main HEPA filter.
1.12.2.2
Auxiliary Generator
An auxiliary generator shall be provided with capacity to power a minimum
of 50 percent of the negative air machines at any time during the work.
When power fails, the generator controls shall automatically start the
SECTION 13281A
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