3
3
SECTION 1
Introduction
General Description
Air is drawn into a fume hood by an exhaust system that produces a
differential pressure between the interior of the fume hood and the
surrounding laboratory. The average velocity of the air moving
perpendicular through the front sash opening of the hood is called the
face velocity. Adequate face velocity is necessary to protect fume hood
users by containing all of the contaminants inside the fume hood.
The AirGard
®
335 continuously monitors fume hood face velocity by
measuring the air velocity of clean air from the room passing through
the air inlet on the front of the monitor. The monitor then reports this
information via audio and visual indicators.
Visual Indicators — An electronic bargraph moves back and forth
through universally recognized red (danger), yellow (caution) and
green (safe) colored zones as the velocity changes. Corresponding
large colored LEDs also illuminate. A digital display can be enabled to
view velocity quantitatively.
Audible Indicator — A continuous audible alarm alerts of a dangerous
situation when the face velocity is in an alarm condition.
Alarm information can be sent to other personnel in a remote location
by means of a relay output.
IMPORTANT:
Fume hoods vary in design and performance. Because
each hood installation and its air flow patterns is unique, the AirGard
335 Monitor must be calibrated in the field on the fume hood in which
it is installed.
Read this manual entirely before installing, calibrating, configuring,
and using the AirGard
®
335. If you need assistance or any further
explanation regarding this instrument, please contact TSI.
