Fume hoods, often a primary Ventilation device in any chemical laboratory, that enables researchers, workers, and students to safely work with hazardous and volatile materials.
Designed to maintain laboratory hygiene conditions and safety of researchers at all times, Fume Hoods protect against flammable or toxic chemicals. These protection devices have clear sashes that slide horizontally or vertically into place and support high working visibility. Constructed for maximum chemical resistance, the leak-proof enclosures do not corrode even with heavy routine use and corrosive spills. The chemical fume hoods circulate and filter air to eliminate possible vapours produced.
The concept of the fume hood is simple — to ventilate dust, fumes, and other contaminants away from users and out of the laboratory. A fume hood is a suitable enclosure that is required to confine those contaminants that must not be released into the laboratory environment. This is essential for providing safe working conditions for the fume hood user and other laboratory personnel.
In order to operate properly, the fume hood relies on a consistent face velocity and exhaust volume. Even the slightest shift in air patterns can affect the performance and safety of your fume hoods. Not only does air movement affect the air entering the hood, it also interferes with the air introduced via the supply outlet, which affects the movement of air at the face of the hood.
CAV – Constant Air Volume (Bypass) Fume Hoods
Constant Air Volume Bypass fume hoods are designed and constructed to allow room air to enter the fume hood by a route other than the sash opening, when the sash is being lowered. Or in other words, Constant air volume (CAV) bypass fume hoods have an alternate path being created to allow air to enter the fume hood when the sash is closed (it may have fixed vertical airfoils, or angled aerodynamic entries, on each side for the purpose) apart from a fixed horizontal airfoil just below the sash and above the work surface. In addition, factory set baffles at the rear of inside the hood, are provided for optimal air flow patterns. This limits the increase in face velocity through the sash opening and results in a relatively constant exhaust airflow rate over the operating range of the bypass.
VAV – Variable Air Volume – Energy Efficient Hoods
Although mostly all the design features of VAV –(variable air volume) fume hoods are similar to those of CAV (constant air volume bypass) fume hoods, but these VAV fume hoods maintain constant face velocity by adjusting the total exhaust air flow as the sash opens or closes, using sophisticated fume hood and laboratory controllers. The commercially available exhaust control system will detect the movement of the sash and adjust the volume of air required to maintain a constant face velocity. This approach minimizes energy costs while maintaining operator protection.
Types of FUME HOODS available
Bench Top Mounted Hoods
The most common type of fume hoods are Bench Top Mounted type Fume Hoods having two parts :
(a) Fume Hood Upper Unit
(b) Fume Hood base cum storage unit
Fume Hoods Base can further have 2 options –
- Floor Mounted Storages with Levellers OR
- Independent Storage Modules with Castors and Upper Unit placed on heavy duty “C” Frame Structure
Low Bench Hoods
Low Bench Fume Hood has a Low Height Fume Hood Base Unit, whereas the upper unit will be taller so as to accommodate bigger size apparatus movement inside the Hood. All other fixtures of the Low Bench Fume Hood are similar to standard bench top mounted hoods.
Walk-In Fume Hoods or General Purpose Floor Mount
If your laboratory requires fume hoods that house large equipment, walk- in fume hoods / Floor Mount Hoods are an excellent option. While the name might indicate otherwise, walk-in fume hoods do not allow users to walk in and out of the fume hood while it is being used. Walk-in fume hoods, which are basically bench hoods that reach the floor, do allow users to walk in and out to set up equipment before and after work begins.
Advantage SPACE DESIGN LABS:
- We offer Fume Hoods as per ASHRAE 110:1995
- Variety of Options in Materials available:
Superstructure & Exterior:
- Frame is made of heavy and sturdy basic structure of CRCA angle of 14 gauge
- Body – Steel: High quality, cold-rolled mild steel, meeting requirements of ASTM A1008; 18 gauge (1.2 mm thick)
- Optionally Stainless steel: Type 304; 18 gauge (1.2 mm thick)
- Z-Black Granite – Most commonly used, suitable for general chemistry applications
- Epoxy – Synthetic High Grade Solid Epoxy 20 mm thick surface for greater chemical resistance
- SS 304 – For general medical applications
- SS-316L – For food grade applications
- A radiused stainless steel (preferably SS 316) Airfoil is offered
- Teflon Coated SS-304 can be offered as an option
Interior Lining: The interior lining of the hood must be resistant to the materials and chemicals to which it will be exposed.
- A superior grade Phenolic Resin Sheet is used as standard for better chemical resistance.
- FRP coating on the CRCA is also on offer as it is also very much chemical resistance.
- Stainless steel is another option suitable for medical and food laboratories
Baffles: A baffle is located in the rear end of the fume hood maintaining a linear flow of exhaust. It can have following options:
- Material remains the same as of INTERIOR LINING – A superior grade Phenolic Resin Sheet OR FRP coating on the OR Stainless steel as chosen.
- It may have at two or three slots.
Clustered System for Multiple Hoods
- In labs where multiple fume hoods are placed in a cluster, the ducting may be combined so that installation as well as running costs get significantly reduced
- Optionally one may include A scrubber system may installed in line of ducting, before blower, so that toxic fumes and gases are not released directly to the atmosphere, but treated before discharge for the safety of nearby environment.