Basic Documentation

Table Of Contents
Laboratory Ventilation Codes and Standards
Siemens Industry, Inc. 38
Topic Requirement(s) Commentary
Room Air
Cross
Currents
(Continued)
American Conference of Governmental Industrial Hygienists (ACGIH)
INDUSTRIAL VENTILATION A Manual of Recommended Practice, 27th Edition
3.7.1. Replacement air should be introduced at a low velocity and in a direction which
does not cause disruptive cross-drafts at the hood opening.
California OSHA Division of Occupational Health & Safety (DOSH) Subchapter 7.
General Industry Safety Orders, Group 16. Control of Hazardous Substances,
Article 107. Dusts, Fumes, Mists, Vapors and Gases
5154.1. Ventilation Requirements for Laboratory-Type Hood Operations:
(1) The outside air supply shall enter the workroom in a manner which will not reduce
the effectiveness of any local exhaust systems.
ASHRAE, 2011 Handbook - HVAC Applications, Laboratories, Pg. 16.5, Air
Currents:
Air currents external to the fume hood can jeopardize the hood’s effectiveness and
expose the researcher to materials used in the hood. Detrimental air currents can be
produced by:
Air supply distribution patterns in the laboratory
Movements of the researcher
People walking past the hood
Thermal convection
Opening of doors and windows
Disturbance velocities at the face of the hood should be no more than one-half and
preferably one-fifth the face velocity of the hood. This is an especially critical factor in
designs that use low face velocities. For example, a fume hood with a face velocity of
100 fpm could tolerate a maximum disturbance velocity of 50 fpm. If the design face
velocity were 60 fpm, the maximum disturbance velocity would be 30 fpm.