Laboratory fume hoods are designed to shield laboratory users from vulnerable to
hazardous materials. Fume hoods provide a secure, enclosed work area for chemical
usage and allow acute ventilation for the user and laboratory. Fume hoods should be
used when working with or potentially producing a substance that integrates a
threshold limit value (TLV) of less than 50 ppm. Fume hoods are typically the most
effective method of protection when working with flammables, corrosives, water
reactive chemicals, and pyrophoric materials.
Using the concepts of fluid dynamics, Drizgas Tech engineers have designed the
Laboratory fume hood to produce horizontal airflow, which reduces the tendencies for
turbulence. The innovative and aerodynamic designs of the sash handle, air foil,
upper dilution air supply and rear downflow baffle work in concert to produce
horizontal airflow patterns that significantly reduce chemical contaminants
concentrations throughout the working area.
A laboratory chemical fume hood is a partially enclosed workspace that is exhausted
to the outside of the building. When used properly, hazardous gases and vapors
generated inside the hood are captured before they enter the breathing zone. This
serves to minimize your exposure to airborne contaminants.
DESIGN STYLES OF CHEMICAL HOODS
There are many types of hoods, each with its own design and function. The main type
of fume hoods classified based on its function are:
Constant Air Volume (CAV) Hoods: With constant volume hoods the
volume of airflow into the hood remainsconstant. As the sash is closed the velocity
of the airflow entering the hood increases. Properpositioning of the sash is vital
to maintaining the optimum face velocity, 80 or 120 feet per minute. Raising thesash
too high lowers face velocity, allowing contaminants to escape from the hood.
Setting the sash too low willresult in very high face velocities. Face velocities in
excess of 120 feet per minute can cause excessive turbulenceand loss of containment.
Variable Air Volume (VAV) Hoods: In this Fume hood the air is
treated and recirculated instead of venting it directly to atmosphere. Fan is
mounted on the top of the hood, or below the worktop. Air is drawn through the front
opening of the hood and goes through the filter, before passing through the fan and
it is recirculated back to the workplace. For a ductless fume hood, filter medium is
essential to remove hazardous and noxious substances.Advantage of ductless
fume hood, they are mobile, energy saving and easy to install.
Technical specifications
Hood body
The visible part of the chemical hood that serves to contain hazardous gases
and vapors.
Sash
The sliding door of the hood. By using the sash to adjust the front opening,
airflow across the hood can be adjusted to the point where capture of
contaminants is maximized. Each hood is marked with the optimum sash
configuration. The sash should be held in this position when working in the
hood and closed completely when the hood is not in use.
Air foil
It is located along the bottom and side edges. The airfoil streamlines
airflow into the hood, preventing the creation of turbulent eddies that can
carry vapors out of the hood. The space below the bottom airfoil provides a
source of room air for the hood to exhaust when the sash is fully closed.
Removing the airfoil can cause turbulence and loss of containment.
Work bench
Generally a laboratory bench top, but also the floor of a floor-mounted
hood, this is the area under the hood where apparatus is placed for use.
Baffles
Moveable partitions used to create slotted openings along the back of the
hood body. Baffles keep the airflow uniform across the hood opening, thus
eliminating dead spots and optimizing capture efficiency.
Exhaust plenum
An important engineering feature, the exhaust plenum helps to distribute
airflow evenly across the hood face. Materials such as paper towels drawn
into the plenum can create turbulence in this part of the hood, resulting in
areas of poor airflow and uneven performance.
Face
The imaginary plane running between the bottom of the sash to the work
surface. Hood face velocity is measured across this plane.
Different type of fume hoods classified based on application
General purpose fume hood
Perchloric acid fume hood
Walk-in fume hood
Portable fume hood
Radio isotope fume hood
Bench top fume hood
Double sided fume hood
Venturi fume hood
Canopy fume hood
Inbuilt fume hood scrubber
Phone Number
+91 842 823 1593 | +91 995 287 7991
Email Address
sales@drizgas.com | info@drizgas.com
Office Address
No. 50, Villianur Main Road, Odiyampet, Puducherry - 605 110, INDIA