Basic Documentation

Table Of Contents
Exhaust Systems
Siemens Industry, Inc. 135
Topic Requirement(s) Commentary
Leakage
ASHRAE, 2011 Handbook, HVAC Applications, Laboratories, Pg. 16.10
DUCTWORK LEAKAGE:
Ductwork should have low leakage rates and should be tested to confirm that the
specified leakage rates have been attained. Designs that minimize the amount of
positive-pressure ductwork are desirable. All positive pressure ductwork should be of
the highest possible integrity. The fan discharge should connect directly to the vertical
discharge stack. Careful selection and proper installation of airtight flexible connectors
at the exhaust fans are essential. If flexible connectors are used on the discharge side
of the exhaust fan, they must be of high quality and included on a preventative
maintenance schedule because a connector failure could result in the leakage of
hazardous fumes into the equipment room. The engineer should evaluate these details
carefully. Machine rooms that house exhaust fans should be ventilated to minimize
exposure to exhaust effluent (e.g., leakage from the shaft openings of exhaust fans).