Fume Hood

Fume hood function and use:

Fume hoods are mainly used in chemical and pharmaceutical industries where use have to use acid or hazardous chemicals.
Help of fume hood, protection from spillage of material and hazardous fume can be made to the user. Fume hoods exhaust these gases to an open environment.

Switch “ON” the Exhaust Air MCB located in Area.
Switch “ON” the MCB and then tube light for Fume Hood, located below the workstation.
Open the sash sliding it in upward direction gently. Hasty operation of sash may damage the sash moving mechanism.
Carry out necessary set up/ activity within the hood.
Close the fume hood sash at least up to safe operation limit when experiment is going on.
Utility service such as water, can be obtained from the water knob by turning it in anti-clockwise direction.
Necessary power supply can be obtained from the sockets provided below the workstation.
After completion of activity, close the sash gently.
Switch off the tube light and then MCB located below the workstation.
Switch off the Exhaust Air MCB.

Maintain cleanliness within the hood.
Carry out an analysis that creates fumes and handles toxic material and concentrated acids under a fume hood.
Keep the sash properly closed during the reaction process.
When not working, close the sash completely.
Avoid raising the sash too quickly. Raise the sash at a moderate rate and allow the air quantity to increase gradually.
Set up reaction apparatus at least 150 mm away from the door to allow the entry of fresh air and for proper evacuation of exhaust.
Do not place electrical or other sources of ignition on the working table of it, when flammables are present.
Maintain proper cleanliness of the hood by avoiding spillage of chemicals inside the hood and ensure immediate cleaning, in case of accidental spill over, to prevent damage to the work top and also for safety.

How a Fume Hood Works?

what is a fume hood?

It is a ventilated enclosure that captures and removes gasesvaporsrs, and fumes from the work area. An exhaust fan on the roof of the laboratory building pulls air and airborne contaminants via ducts and exhausts them into the open environment.

A sliding front sash and an inner baffle are standard features of a it seen in the laboratories.
The sash may move vertically, horizontally, or a mix of the two, depending on its design, and acts as a barrier between the worker and the experiment, providing some protection to the hood user.

The air is directed through the hood’s slots and baffles, which can be modified in various hoods for the most balanced flow.

Excessive material storage or equipment should not block the baffles, as this has a major impact on the exhaust flow within the hood and, as a result, the efficacy of hood capture.

The air foil, a beveled frame surrounding the hood face that eliminates sharp curves to prevent turbulence, provides for even airflow into the hood.

Two basic types of fume hoods:

Constant volume: Exhaust flow rate or quantity of air drawn through the hood is constant in rate.
Variable air volume (VAV): Exhaust flow rate or quantity of air drawn through the hood differs as the sash is elevated or lowered in order to maintain a constant face velocity

Generally calibration of Fume hood performed on Annual basis.

Calibration contain following test:

Physical Check
Air Flow Visualization (smoke test): By using the dry ice or other visual fog has been checked for pattern of flow.
Air velocity: Should be checked for the described velocity of air against master Air Velocity Measuring Instruments

It price varies from 42,000 to 2,50,000 INR depending on size and function.

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