Fume Hood: How to Choose the Right One? Why it's a Must for Labs?

Scientists engage themselves in essential experiments all the time in laboratories. Not all of those experiments are free from risks. Chemical laboratories often include complex experiments with poisonous gasses. These labs must possess a well-built and advanced fume hood. 

What is a fume hood?

A fume hood is equipment explicitly designed for use in laboratories. It’s basically a large box which is placed above a lab workbench. One side of the box has a shutter or a door, and another side has glass or sheet walls. Generally, if you have to show a risky experiment on a large lab table to an audience, you will need a chamber with a glass wall. Otherwise, the metal fume hood of your lab facing the wall is sufficient.

The fume hood sucks out the air from the box. Naturally, it consists of an air suction pump or exhaust fan. The fan or pump is located just above its work area. A sealed vent pipe connected to the fan comes from the fume cabinet. The pipe may go out into the free air or a filter block as well—also, fume hoods function without an air duct or vent.

The lower part of the box, which stays under the lab table, can be left open. You can utilize that area as storage cabinets too.

What does a fume hood do?

A fume hood or fume cupboard, a must-have for a lab, plays a vital role in:-

• Protecting you from toxic fumes
• Keeping the sample or experiment safely away from contamination
• Protecting you from the danger of spills or explosions

A fume has three parts to perform the functions mentioned above correctly. Those parts are the system, a table, and an enclosure. 

The table: - It is a C-frame or H-frame table made of CRCA with storage like a cabinet or a drawer. The cabinet or drawer may be used to store lab equipment. 

The enclosure: - This portion of a fume hood is also made up of CRCA and has a glass shutter at one side. The glass of this shutter has to be of good quality. Nowadays, there are advanced glasses for these enclosure shutters available; some of them are even explosion-proof.

There is a good lighting system inside the cabinet. The hood contains water connections and LPG, too, along with a drain which works during spills.

The air suction system is placed above the box or towards the wall. It is built with an air pump or exhaust fan and a duct. 

The stronger the airflow is, the stronger the pump will be. The airflow strength in a fume hood generally starts from a minimum of 4-8 meters per second. 

Different types of fume hood:

Three types of fume hoods are common for use in the labs. 

• Ducted fume hoods

Most labs and industries use ducted fume hoods. They draw the air from the space to push it into the outside environment through ducts. Some of the ducted fume hoods have VAV (Variable Air Volume) system inside them. 

• Ductless fume hoods

instead of a vent, these hoods have a filter unit above the fan. The blower takes all the fumes from the air inside the box and passes them for purification through the filter. This way, it filters the air to clean it and send it into the room again.

• Special fume hoods

There are other types of special fume hoods, too, based on their applications. They protect you from explosions, radiation, hot hydrofluoric acid and similar materials.

There are specializations in functions as well, like diluting harmful fumes and flowing out the hood box. 

• Downflowing fume hoods

Sometimes, the gasses released from the experiments are heavier than air. A normal fume hood with a blower on the top can't gather such gas. That is when a downflowing fume hood with a blower in the bottom is effective. The air goes downwards from the top of this hood.

Fume Hood Safety: EN 14175 Regulations and Compliance

A fume hood is safety equipment for people working with toxic chemicals and harmful gases. Therefore, it has to be subject to specific regulations. A ducted fume hood must follow EN 14175 regulations. To meet safety standards, maintaining legal requirements is very crucial.

BS EN 14175 is the British and European Standard, which requires every ducted fume hood to comply with. Only this testing can ensure that the ducted fume hood is eligible for laboratory placement. It also ensures there is no issue in the ducted fume hood. 

So, every ducted fume hood should undergo EN 14175 tasting once a year. It confirms no issue in its pressurization, location and HVAC system.

The EN 14175 testing basically covers three areas:-

• Face Velocity

A proper sampling method and anemometers test the velocity level at different points through the face of the ducted fume hood. 

• Smoke Patterns

This test visualizes smoke patterns to assess the airflow inside the fume cabinet.

• Tracer Gas Containment

This test determines the equipment's ability to contain chemical vapours and keep the environment safe. SF6 tracer gas is released during the test to check for gas leakage. 

Overall, EN 14175 testing meets legal requirements and, at the same time, eliminates all the risk factors to ensure safety and higher productivity.

What does a top-quality fume hood feature?

A highly efficient fume hood caters to the personalized needs of the laboratory. Besides, it's durable and resistant to fire, heat and chemicals. The trusted brands offer fume hoods of different sizes and types. All of them are structured and built according to IS:513. A renowned fume hood brand offers systems that are easy to use and clean. 

Final Words:

A fume hood of any type, size and specification protects the lab workers in many ways. Therefore, using a standard quality fume hood properly is of utmost priority for any laboratory.