What is the cabinet?
steam cabinets, often called hoods, are used to protect laboratory workers from hazardous chemicals. The air protok through the cabinet prevents toxic chemical vapors from praising into the room. It is important to note that the hood of the pys can look similar to other laboratory safety devices, a biological safety cabinet, but both are not interchangeable - the hoods should only be used for chemicals and biological cabinets only for biohahazard materials.
A typical hood of smoke is a completely closed vent with a ventilation. The wing in front of the cabinet, usually made of glass, allows users to access the inside of the bonnet. Crossings can move horizontally or vertically or in some cases in both directions. Some substances, such as radioactive materials and chlorhloric acid, require specialized hoods of smoke and should only be used in such a bonnet. Any chemicals and equipment inside the bonnet should be set at least 6 inches (about 15.25 cm) backfrom the opening of the user.
The continuous stream of air flows through the cabinet, captures dangerous vapors and vent them to the outside of the building. Once dangerous vapors are outdoors, their outdoor concentrations are so small that it does not pose any risk. The efficiency of the hood of smoke depends on the speed of air flowing through it. The speed of air on the bonnet - the point where the wing is lifted to allow the user to access materials inside - is normally tested to ensure appropriate performance.
The required air speed for the smoke box depends on the toxicity of the materials used inside. Conventional, less dangerous laboratory chemicals, such as ethanol, require only a C -class cabinet with a face speed of 75 to 95 feet per minute (FPM) or 23 to 29 meters per minute (MPm). More hazardous materials like most acids require three cabinets with face speedIt is 95 to 110 fpm (29 to 33.5 Mpm). Extremely toxic chemicals, including carcinogens, must be used in a class and with an average face speed of 115 to 125 fpm (35 to 28 Mpm). No sense on the face of the class cabinet and can be less than 100 fpm (30.5 Mpm).
Standard hood of smoke exhausts constant air volume, causing to reduce the speed of the face. The bypass of the bypass uses the constant air volume (CAV) technology, which at all times removes the same volume of air, even if the wing is closed but does not cause the increasing speed of the face as a standard bonnet. Variable air volume (R&D) and auxiliary air hoods are designed to reduce energy consumption while maintaining the protective value of cabinets. Laws of hood do this by reducing the volume of exhaust gases when the wing is reduced, while the auxiliary air hoods lead outer air as part of the exhaust gas.