Laboratory exhaust, Types of Laboratory exhaust, What is Laboratory exhaust
Laboratory exhaust speaks types of laboratory exhaust and what is laboratory exhaust.
There are usually other sources of laboratory exhaust other than fumehoods found in a laboratory.
Thes other exhaust can be exhaust arms and canopies and must be considered when calculating the volume of supply air required. Remember the laboratory must be in a negative pressure compared to adjacent areas. This is to ensure airflow is from the adjacent area to the laboratory and then out.
Exhaust Arms
These are also referred to as "snorkels" and are flexible arms equipped with cones which can be directly positioned over work being done on work benches.
There are usually multiple snorkels in the lab with each being equipped with an air damper. When the snorkel is not being used the damper may be closed.
Often each snorkel has a light which allows detailed work to be illuminated.
The throat velocity of the snorkel should be between 800 fpm and 1200 fpm capture velocity. This will depend on the number of snorkels being used at any one time.
Exhaust arms are usually served by an individual exhaust fan located on the roof or an upper mechanical room.
Canopy
Canopies are horizontal permanent hoods which cover a work bench or other piece of equipment. It is a permanent non-moveable exhaust device.
The throat velocity of the canopy is usually balanced to 1000 fpm capture velocity.
Canopies are usually served by an individual exhaust fan located on the roof or an upper mechanical room.
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