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LAB ESSENTIALS
Ductless fumehoods, alsoknownas
carbon-filteredenclosures, are self-
contained, filtered laboratory
enclosures that remove thehazardous
fumes, vaporsandparticles from the
laboratory. Unlike traditional fume
hoods, installation costs arevery low
andnoductwork is required. Therefore,
manypeople think it isa slamdunk
when theyfirst learnof them.
“It takes careof thechemical fumes, it’s
cheaper, and it’saneasier installation. It
onlymakes sense, right?”Not so fast!
Thereare some important things to
considerbeforemaking thefinal
decision topurchaseaductless fume
hood. Take these4aspects into
thorough consideration tobe confident
thataductless fumehood is the right
choice for your laboratoryandyour
facilityoverall:
1. Isyourgeneral application
appropriate foraductless fume
hood?
Ductless fumehoods shouldonlybeused
as lightdutyandprocess specific fume
hoods. Thismeans that:
• A limitednumberofdifferent
chemicals shouldbeused, nomore than
about10different chemicalsper
applicationatmost.
• Noextremeheating shouldbecarried
out in thehood, i.e. aciddigestion
applications.
• Modestvolumes shouldbeused, ~500
mlsper chemicalor less.
• Moderatechemical exposure times
shouldbemaintained, ~2-3hoursaday.
Ifyourapplicationdoesnotmeet these
parameters, a standardducted fume
hoodorafiltered fumehoodare likely
thebestoption formaximum safetyand
economical feasibility. Filtered fume
hoodsare the“bigbrother”ofductless
fumehoods; these laboratoryhoods
utilizeadvancedchemicalfiltrationand
detection foran increased levelof safety
to rival standardductedhoods.
At thispoint you shoulddiscussyour
applicationwithaFumeHoodSpecialist
toconfirmwhichkindof fumehood is
theprimary recommendation.
2.Will thechemicals involved inyour
applicationbeeffectivelyfiltered
with theavailablecarbonfilters?
Typically, ductlesshoodswillbeoutfitted
withchemical-specificfilters. Specific
filter types increasechemical trapping
capacity fordifferent chemical families;
however, somechemicals cannotbe
safelyfilteredoraren’tfiltered
effectivelyenough toallowductless
hoods tobeafinanciallyviableoption.
Labconcooffers sevendifferent typesof
filters for various chemical groups:
• HEPA (HighEfficiencyParticulateAir)
Filter-99.99%efficientparticulatefilter
for chemical powdersandparticulates
• OrganicFilter-Activatedcarbon to
chemicallyadsorborganicvapors
• Acid-SulfurFilter-Impregnatedcarbon
toneutralizeacidsand sulfur-containing
compounds
• Ammonia-AmineFilter-Impregnated
Carbon toneutralizeammonia/amine
compounds
• FormaldehydeFilter-Impregnated
Carbon toneutralize formaldehyde
• MixedBedCarbonFilter-60%
ImpregnatedCarbon toneutralizeacids
and sulfur-containingcompounds
(20%), ammoniaandaminecompounds
(20%), Formaldehydecontaining
compounds (20%)and40%activated
carbon fororganics
• RadioisotopeFilter-Impregnated
carbon toneutralize radioisotopes
Ifallof thechemicals involved inyour
applicationmatchoneof thesefilter
types, it isagood sign thatyour
applicationwillbe suitable forusewitha
ductless fumehood;however, thereare
somechemical exceptionswitheach
filter type. For instance, someorganics
(suchasmethanol)areveryvolatileand
lightweight, andarenoteffectively
adsorbedon theorganicfilter. In
addition, someacids (likeperchloricacid)
present specialhazardsand shouldbe
used ina specialized fumehood.
So thebestway todetermine ifyour
chemicalsarecompatiblewith thefilter
typesoffered is to requestachemical
assessment fromourChemical
Specialists. Theywill reviewyour
application tohelpyoudetermine if it is
suitable,makeappropriateequipment
andfilter recommendations, andprovide
youwithanynecessaryprecautions.
3.Howoftenwill youhave to
replaceyourfilters?
Althoughyouwillnothave theadded
costofductwork installationandwiring
associatedwitha standard fumehood,
youwill stillwant toconsiderhowoften
youwouldneed to replaceyourfilters to
calculateyourestimatedannualfilter
costs.Youcan thenweigh thatagainst
thecost to install a standard fumehood.
Alsoconsider theenergycostof running
a standard fumehood,which removes
expensive temperedair from the
laboratory, taxing theHVAC system.
4Things toConsiderBefore
ChoosingaDuctlessFumeHood
ByDianeWilliamson, SeniorApplicationSpecialist, Labconco
