With the mode operations undergoing radical changes, quality lab furniture pieces have become the need of the hour. Quite naturally, lab equipment is no longer limited to just workbenches. Additions like fume hoods are widely seen in laboratories across the globe. Many critical lab experiments often include working with highly reactive substances, whether it’s harmful chemicals or pathogenic samples. To prevent air contamination, many working professionals have opted to install chemical fume hoods in their laboratories. By definition, chemical fume hoods play the role of a filter, removing vapors, harmful gases, suspended particles, toxins, as well as other flammable, corrosive substances.
Types of Chemical Fume Hoods
Based on the operations, various kinds of chemical fume hoods are on offer. Here are some of the commonly used fume hoods in the laboratory:
Full Sash – In full sash chemical hoods, the face velocity increases as the sash is lowered and decreases when it is elevated, so lab operators need to regulate airflow on the basis of applications. Usually, a small bypass chamber above the sash controls the airflow in the hood.
Bypass Hood – Unlike the full sash hoods, bypass hoods have an opening above the sash, while the airfoil ensures a relatively constant face velocity irrespective of the position of the sash.
Walk-in Hood – As evident from the name, walk-in-hoods are manufactured so that lab workers can walk into the hood, setting up bulky equipment.
Auxiliary Hood – Auxiliary hoods may be full sash of bypass hoods, wherein the air to be filtered, comes from a source outside the operating laboratory. Generally, the sash is located right above the work table, while the air flows into the sash and is collected through the sash opening.
Others- Apart from the above-mentioned variants, there are other interesting types of chemical fume hoods, such as Perchloric acid hoods or the Radioisotope hoods, which are designed to eliminate volatile chemical compounds and radioactive wastes from the air.
Chemical fume hoods are a complex structure, which includes a number of intricate components, from sash glass, linings, ductwork to airflow monitors and hood exhaust systems. Only a multi-paned safety glass is chosen for fume hoods, wherein it can withstand heavy blows. The inner compartments of such units come with stainless steel linings to ensure the safety of the operators. As for the ductwork, a chemically compatible duct is selected for added security. The sash counterweight system aids the movement of the sash. For adequate support, lead or steel weights are used, balancing the weight of the sash. The airflow is controlled by the airflow monitor, keeping the air close to the safety levels.
Operating a Chemical Fume Hood
To optimize the functionality of fume hoods, the following steps may be taken:
- To begin with, proper care must be taken to ensure the sash is at the right height. This can be done by referring to the profile stickers appearing in the front of the hood.
- For the filter to work accurately, operators should eliminate factors like pedestrian traffic, frequent opening, and closing of the doors, etc.
- One of the common mistakes people make is attaching airfoils on the floor of the hood. This should be avoided at any cost, as blocking the airfoil will interfere with the airflow.
- Any heavy equipment must be kept at a safe distance from the hood.
- Also, operators are recommended to work right inside the hood for best results.
- When the work is done, workers should close the sash and ensure the surface is cleaned properly to prevent accidents.
Available with a variety of optional features, chemical hoods can be a favorable asset to the laboratory in many ways, provided a proper selection is made based on the working requirements. To ensure a good investment, purchasers are recommended to research all they can on this beneficial equipment and work with an accredited source, to make their final purchase.