The personnel that continuously work in a laboratory need to have the proper safety conditions, in order to protect them from any hazardous tasks. A laboratory fume hood is vital to keep the quality of air in a laboratory. It is a type of ventilation system that provides personal protection against toxic fumes, vapours and dust. Also, it acts as a physical barrier to protect against chemical spills, runaway reactions and fires.
They are often a large piece of enclosed equipment that creates the working area. They are leak-proof, which means that their enclosures will not corrode even with heavy routine use and corrosive spills. The chemical fume hoods circulate and carbon filter air to eliminate possible vapours produced.
The front of a fume hood is a sash window, usually in glass, able to move up and down on a counterbalance mechanism. They have different widths in a range from 1000 mm to 2000 mm. The depth varies between 700 mm and 900 mm, and the height between 1900 mm and 2700 mm. Depending on the design, there can be from one to three operators.
There are three basic functions of a fume hood:
- To protect the user from inhaling toxic gases.
- To protect the product or experiment.
- To protect the environment
There are two main fume hood types, ducted and recirculating (ductless). They both work with the same principle: air is drawn from the front side of the cabinet and either expelled outside the building or made safe through filtration and fed back into the room. These devices are usually placed against the walls and filled with infills above in order to cover up the exhaust duct.
Ductless (recirculating) fume hoods
This unit has a fan on the top that sucks the air through the front opening and through the filter and then is fed back to the workplace. It removes hazardous material and this type of fume hood is useful when the hazard is well known and does not change. Ductless fume hoods are often not appropriate for research applications where the activity, and the materials used or generated, may change or be unknown. The great advantage of this equipment is their mobility. However, carbon filters require regular maintenance. They save energy and are environmentally friendly.
Ducted fume hoods
There is a large variety of ducted fume hoods, most of them with conditioned air (heated or cooled) exist. In most designs, conditioned (i.e. heated or cooled) air is drawn from the lab space into the fume hood and then dispersed into the outside atmosphere. In other cases, the air is recirculated and returns to the laboratory purified. In this last case, the idea is to minimize energy and running costs. The fume hoods serve to evacuate hazardous levels of the contaminant.
Other types of fume hoods
Depending on the size and features, there are many different specialized types of fume hoods. Some of them are:
Distillation Fume Hood. They have a low working surface and a wide working space that allows the installation of distillation equipment inside the cabin. The rest of the characteristics are similar to a standard fume hood.
The fume hood for perchloric acid. This equipment has a water wash system in the ductwork, to prevent explosive crystals and fumes settlement. The ductworks are internally cleaned with a series of sprays. This is the ideal unit for working with this acid.
The radioisotope fume hood. This equipment is the ideal to handle radiation and protects the user from radioactivity. It is built with lead and the unit is coved with a stainless steel liner and coved integral stainless steel countertop and rounded corners.
Fume Hood for acid digestion: This equipment is built in polypropylene so it resists corrosive effects of acids. Glass is built in polycarbonate and the ductwork is coated with Teflon.
Walk-in Fume Hood. These units are used when requiring large equipment. They do not have a working surface so the equipment can go inside the cabin.
Demonstration Fume Hood. This equipment has four sides made of glass so it is the ideal for teaching because it can easily observe the inside from every angle.
Biosafety cabins and laminar flow are usually confused with fume hood, but the former equipment use filters that do not remove the chemical exhaust, so they are hardly ever used with work that involves chemicals.
Thomas Edison is considered to be the first scientist concerned about ventilation in the laboratory and used a chimney in his lab to exhaust noxious fumes and odors from his experiments.
Frequently Ask Questions
How do I know the right fume hood for my laboratory?
Know the chemicals you use. With this information, you can meet with representatives from Kalstein to know the adequate model for your needs. Also, you may decide if a ducted fume hood is better than a ductless fume hood according to your needs.
How is the working surface important to choose the appropriate fume hood?
Consider aspects such as room’s ventilation and space available. Remember that it must be away from doorways and air conditioning systems. Then decide which model is the one you need: table-top or full sized.
Follow this link HERE to see our models and features to determine which one is the appropriate for your lab.
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