November 9, 2019 by Dulce Lienau
Personnel working permanently in a laboratory must have adequate safety conditions to protect themselves from dangerous work. A fume hood is essential to maintain air quality. It is a type of ventilation system that ensures personnel protection against toxic fumes, vapors and dust. In addition, it acts as a physical barrier to protect against chemical spills, uncontrolled reactions and fires.
Gas extraction hoods with recirculation
The ductless extractor hood is based on the principle of recirculation of air. This unit has a fan on the top that draws air through the front opening and through the filter and is then returned to the workstation. It eliminates hazardous materials and this type of hood is useful when the danger is well known and does not change. Ductless hoods are often not suitable for research applications where the activity and materials used or generated may change or be unknown. The great advantage of this equipment is its mobility. However, charcoal filters require regular maintenance. They save energy and respect the environment.
There is a wide variety of duct hoods, most with air conditioning (heated or cooled). In most designs, conditioned (i.e. heated or cooled) air is drawn from the laboratory space into the hood and then dispersed through ducts into the outside atmosphere. In other cases, the air is recalculated and returned to the purified laboratory. In the latter case, the idea is to minimize energy and operating costs. Fumehood is used to evacuate dangerous levels of contaminants.
Other types of hoods for Laboratory
Depending on size and features, there are many types of hoods. Some of them are:
Distillation hood: They have a small work surface and a large working area that allows the installation of distillation equipment inside the cabin. The rest of the features are similar to a standard hood.
The extractor hood for perchloric acid: This equipment has a water wash system in the ducts to prevent the formation of explosive crystals and fumes. The ducts are cleaned internally with a series of aerosols. It is the ideal unit to work with acid.
Radioisotope hood: This equipment is ideal for handling radiation and protects the user from radioactivity. It is constructed of lead and the unit has a stainless steel liner.
Acid digestion hood: This equipment is made of polypropylene so that it withstands the corrosive effects of acids. The crystals are replaced by polycarbonate glass and the pipes are covered with Teflon.
They are often big closed equipment that creates a work area. They are waterproof which means they do not corrode even with routine use or corrosive spills. Chemical hoods circulate and filter the air to eliminate any vapors produced.
The front of a Lowhood is a sash window, usually made of glass, able to move up and down on a counterweight mechanism. They have different widths in a range of 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 may be one to three operators.