Kewaunee Supreme Air Series, Руководство по эксплуатации и техническому обслуживанию

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VFHOMT-11/18 -
23
Recommended Work Practices
(continued)
Maintaining the Protective Air Barrier for a Safe Work Area
When you stand in front of a laboratory
fume hood, the air passing your body
to enter the hood forms a zone of low
air pressure directly in front of you
which extends into the hood. Since
contaminants may enter this turbulent
area from inside the hood, you should
keep all hazardous materials at least
six inches inside the hood, behind the
protective air barrier.
(See Figure 3.)
Figure 3
Formation of Protective Air Barrier
Checking Fume Hood Performance
To confirm that your fume hood
exhaust system is working properly,
the Occupational Safety and Health
Administration (OSHA) recommends
that all hoods be equipped with an
airflow monitor. Inspect both the
monitor and the system periodically
for malfunctions.
For some applications a pressure
gauge connected to the exhaust
duct is sufficient. The safe pressure
range should be marked on the
gauge. When using more hazardous
contaminants, a fume hood alarm
such as the Kewaunee Air Alert 300
or Air Alert 600 Digital Face Velocity
Alarms should be used. These alarms
provide both a visual and audible
warning when the exhaust flow
becomes unsafe.
If your hood is equipped with a
variable air volume controller (VAV)
with alarm capabilities, then an
additional alarm is not necessary.
You should have a qualified
technician thoroughly test your fume
hood before you use it the first time
and at least once a year after that.
You should also have your hood
tested after any modification to the
laboratory ventilation system or other
factors which may affect hood exhaust
capability or room air flow patterns.
The farther behind the fume hood
protective air barrier you place the
source of contaminants, the greater
the protection the hood provides.
Therefore, place the equipment and
contaminants as far back inside the
hood as possible, being careful not to
block the slots in the rear baffle.
(See
Figure 4.)
Never place apparatus so
far back that you have to put your head
into the hood while the procedure is
generating contaminants.
Figure 4
Effect of placement of contaminate source
Bad Better Best