Table of Contents
Advertisement
exhaust and recirculating air. This balance is
critical because too much positive or negative
pressure in the work area could mean an outflow
of pathogens or an inilow of room contamination.
The balancing damper adjusts the volume of the
exhaust air so as to maintain the proper supply
and calculated intake air velocities. The damper is
preset at the factory and should not be changed
unless the proper airflow balance carmot be
achieved after new filters are installed. On those
occasions when adjustment becomes necessary,
adjustments can be performed by a damper
quadrant located on the top of the unit.
The procedure is as follows:
1.
Loosen the quadrant wing nut.
2.
To decrease exhaust airflow, move the
quadrant arm towards the front of the unit
(clockwise rotation).
3.
To increase exhaust airflow, move the
quadrant arm towards the rear of the unit
(cotmter-clockwise rotation).
4.
When final adjustments have been achieved,
make sure to tighten the wing nut on the
damper quadrant.
5.
If, after adjusting the darnper, both supply
and exhaust are high or low, adjust the speed
control.
Troubleshooting
Here are some suggestions based on our
experience with the use and misuse of biological
safety cabinets.
DANGER!
Whene71er the potentially contaminated areas
of your cabinet
1nust
be· entered, 1nake
s;.tre
1
that the unit is first decontaminated by use of
j
appropriate 1nethods.
1
When a smoke test indicates that there is air
flowing from the interior of your cabinet into
the surrounding room -
1.
Make sure that the shipping cover is
removed from the exhaust filter and that no
other objects are blocking the airflow.
2_
If your cabinet is cmmected to an in-house
exhaust, make sure that there is adequate
exhaust suction and the system is not
producing back pressure. Also, be sure the
dampers are open. Re-balance the exhaust
system to handle an adequate volume of air
and static pressure (suction). Consult with
building maintenance people.
3.
The exhaust filter mav be loaded with dirt if
the urtit has been in service for some time.
Decontaminate, and replace all filters.
4.
There may be high cross-drafts in the room
which are causing the outflow of smoke.
Check the airflow balance, following the
procedure recommended earlier in this
chapter. Eliminate the source of the cross-
draft.
When there is low airflow within the work area
and through the exhaust filter -
1.
Check the incoming line voltage. Low
voltage may cause the blower to operate at a
slower-than-designed speed. Although this
should be corrected in the building's electrical
system, you may be able to compensate by
adjusting the blower speed control clockwise
until proper velocity is reached. The control
is located on the left side of the light canopy.
2.
The reduced airflow may be caused by
damaged or leaking filters. Decontaminate
the unit and replace the filters at once.
If there is no air flow within the work area -
1.
If the lights and electricaJ outlets also fail to
operate, make sure the
Llnit
is plugged into a
dedicated eJectricaJ outlet (grounded 20 amp,
115 Volt, 60 Bz). Also make sure that the
blower switdl is turned on. The yellow
indicator above the button should be lighted.
Hide quick links:
Advertisement
Table of Contents
