Laboratory-Specific Duct Layout

Special laboratory conditions should always be addressed specifically. In laboratories where dust prevention is of concern, ductwork that would contain dust particles should not pass through neighboring laboratories. Ducts, dampers, and control devices should be run in corridors whenever possible for ease of access and modification.

Good engineering practice dictates that contamination of ducts in case of fire or other accident should be prevented. The layout of a laboratory duct system should always minimize changes in the flow direction and avoid abrupt increases in area because these features tend to cause flow separation and turbulence.

Safety and code considerations should always be kept in mind in laboratory design. Key points include:

• Transit ducts are not allowed in spaces used for evacuating people during a fire, i.e., stairs, shelters, etc.;
• Ducts used to transport abrasives and dust must be designed following explosion protection standards, as outlined in the Uniform Mechanical Code (UMC) and Uniform Fire Code (UFC);
• Ducts used to transport abrasives cannot be located in basements and under internal underground channels;
• Ducts cannot carry combustible or non-combustible materials in combustible packaging;
• Local exhaust systems containing combustible material and/or exploded gases must not come in contact with supply ducts.

Ducts carrying high-temperature air (above 80°C (176°F)) or ducts used to remove dust or other explosive substances must be separated from other ducts. The distance between ducts and structures should be no less than 0.3 m (1 ft). Also, ducts with high air temperatures should be located above ducts with lower temperatures.