What is “Automatic By-pass” type airflow?

Automatic By-pass type airflow is widely used worldwide. It provides much safer environment than regular conventional type fume hood. This system distributes the airflow in the fume hood evenly & ensures quick fume exhaust. Air turbulence are avoided and fume hood processes are not disturbed. That means you will not face the problems like burner going off, slow distillation rates, damage of fragile instrumentation.



Which option should I choose: By-pass or LCV?

For non A.C. labs, you should go for Automatic By-pass model. For A.C. labs, one has to choose LCV models. The selection will depend upon your fume hood usage and other HVAC parameters. Please feel free to contact us to select right model for your applications.



I use Perchloric acid in my fume hood, do I need to have a special Perchloric acid hood?

Perchloric acid hood is dedicated to perchloric acid usage only. Organic materials should not be used in that hood, because explosion may occur when perchloric acid reacts with organic materials. Perchlorates get deposited in the ducting and it may react with the organic chemicals, hence a special ‘washdown system’ is provided with such fume hoods. If your usage of Perchloric acid is less than 50% of total chemical usage, you need not have a special hood.



Are fume hoods required to have explosion proof electrical fixtures?

No. All fume hoods have electrical points isolated from inner chamber of the fume hood. Also, the tube light fitting is doesn’t even come in contact with the fumes generated inside.
Still, where there is an extraordinary hazard, the user may wish to use explosion-proof electrical fixtures for added safety.

What is the exhaust volume for an acid storage cabinet?

An acid storage cabinet vented through the hood work top will have an exhaust flow rate of approximately five to ten cubic feet per minute (CFM).



What is the safe face air velocity for my fume hood?

As such various organizations state different face velocity ranges as acceptable, but 100 FPM (Feet/ minute) has been accepted norm worldwide. All LabGuard fume hoods satisfy these norms.



At what sash height should I measure the hood face velocity?

If the hood has a sash stop or a sash label to indicate the safe sash height, the face velocity should be measured with the sash at the stop or label. Usually it is within the range of 12 to 18 inches from worktop.



What standards exist for testing fume hoods?

SEFA 1.1 standards, ASHRAE 110 Method of Testing, OSHA standards are available for fume hood testing. All standards suggest face velocity measurements, while few also suggest smoke pattern visualizations. LabGuard Fume hoods follow all international face velocity standards.



What type of exhaust duct should be used?

The most often used material for exhaust ducting is PP (Polypropylene) or PVC. It has good chemical resistance. For radiological hoods, stainless steel should be used. If no corrosive applications, galvanized steel may be used.



Where is the hood exhaust fan (blower) located?

The fan may be in-built, on the top of the fume hood or away from the hood, either on the outside wall or on roof. In facilities with many hoods, several hoods may be connected to a one exhaust fan.