Basic Documentation

Table Of Contents
Laboratory Ventilation Codes and Standards
Siemens Industry, Inc. 28
Topic Requirement(s) Commentary
Automatic
Sash Closure
American National Standard for Laboratory Ventilation ANSI/AIHA Z9.5-2003
3.1.1.4 The following conditions shall be met before using automatic sash closing
devices: users must be made aware of any limitations imposed on their ability to use
the hood;
Automatic sash positioning systems shall have obstruction sensing capable of
stopping travel during sash closing operations without breaking glassware, etc.
Automatic sash positioning shall allow manual override of positioning with forces
of no more than 10 lbs (45 N) mechanical both when powered and during fault
modes during power failures.
Implementing sash closure devices should be
done with consideration of the following:
Energy savings will not occur if automatic
sash closures are applied to non-VAV
fume hoods. Except for VAV fume hoods,
hood air consumption is not reduced
when sashes are closed on CAV fume
hoods since CAV hoods cannot vary
overall airflow based on sash position.
Safe user practice and discipline requires
call for closing the sashes whenever
possible. Automatic sash closures tend to
negate this aspect of safety
consciousness and the time delay before
automatic sash closures operate may be
reduce the overall time that the sashes
are actually closed.
Alternate means to encourage and attain
sash closure by the users include having
‘warning beeps or chirps’ when
unattended hoods sashes remain open.