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FAQ's
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1. How often should I have my laminar flow hood certified?
You should have your cabinet certified at its initial installation, when maintenance is performed, anytime you move the hood, and at least
annually thereafter. It is recommended semiannually, although some agencies require it twice a year. Check your local and state codes
2. How often should I have the HEPA filters changed in my cabinet or bench?
HEPA filters last approximately 5 years or more before they need replacement. They will require replacement if they are damaged or loading
abnormally, as seen with some mini pleat HEPA filters. Some filters have been seen to last 15 years or more.
3. What is a HEPA filter?
HEPA is a acronym for High Efficiency Particulate Air. To qualify as a HEPA filter it must have a minimum efficiency of 99.97% (0.03% penetration)
at .3 micron. The highest rated HEPA filter has a efficiency of 99.99% at .3 micron.
4. What is a ULPA filter?
ULPA is a acronym for Ultra Low Penetration Air. This type of filter must have an efficiency of at least 99.999% (0.001% penetration)
at usually .1 to .2 micron.
5. Are there any requirements I need to follow if I duct my hood to the outside?
YES, The main requirement is to have an auxiliary roof mounted blower connected to the duct work that will assist in exhausting the air
from the hood and keep the duct under negative pressure. There are many things to consider such as exhaust alarms, the type of connection
(thimble or direct), and size of the blower and it should always have a damper. Also, there is significant vibration that exsists with hoods
that require larger volumes of exhaust. You should always contact your certifier or the manufacturer of the hood
before any modifications are
made. Chances are it will save you time and money.
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