Lab fume hoods, specified for your lab
Laboratory fume hoods
Putting a fume hood into a laboratory is rarely about the hood alone. What decides safety is how it meets the bench, the services and the room's air. Get the hood right and the lab wrong, and it still will not contain.
- ASHRAE 110
- EN 14175
- ANSI/AIHA Z9.5
- 0.3 to 0.5 m/s at the sash
What a laboratory fume hood is
A laboratory fume hood is the ventilated workstation a lab uses to handle chemicals safely. Room air is pulled in across a glass sash and sweeps the fumes off the work. That air is then exhausted, or filtered, away from the operator's breathing zone.
- ASHRAE 110
- EN 14175
- ANSI/AIHA Z9.5
- ISO 14644
This page takes the lab fit-out view: choosing, sizing, siting and servicing hoods for a real laboratory.
It is the single most important engineering control on a chemistry bench. In most Indian labs, it is also the item most often under-specified.
For the plain English how it works, and how a fume hood differs from a laminar flow hood or a biosafety cabinet, start with the fume hood overview. This page answers the lab manager's next question. Which hood, at what spec, sized and laid out how, for your laboratory.
Behind that view is a team that has delivered 2,000+ controlled environments since 2004, across every industry that needs controlled air. Cleanroom, HVAC and validation sit with one accountable group, never stitched together from subcontractors. When we talk about hoods, we are talking about the whole lab they sit in.
- Controlled environments
- 2,000+
- Building them since
- 2004
- Industries served
- 7
What makes a fume hood “laboratory grade”
Not every ventilated box is a laboratory fume hood. Five things separate a working hood from a metal cupboard with a fan in it.
- A measured, monitored face velocityInward air across the sash is held at roughly 0.3 to 0.5 m/s (60 to 100 fpm). An airflow monitor with an alarm then tells the operator it is genuinely containing, not just running.
- Chemically resistant constructionThe liner and worktop are chosen for the chemistry. Epoxy coated steel covers general work and polypropylene (PP) suits acids. Worktops come in phenolic resin or ceramic, under safety glass sashes.
- A proper baffleIt spreads the pull from top to bottom, so capture stays even across the whole opening. A hood with a blocked or badly set baffle can hold its average face velocity and still leak from one corner.
- A sized exhaust pathGet this one wrong and the hood starves while the room goes negative. A ducted hood needs a correctly sized blower. These are the laboratory fume hood exhaust fans an installer matches to the duct run, and the lab has to supply the matching make-up air.
- Containment proven to a standardASHRAE 110 testing and ANSI/AIHA Z9.5 practice, with periodic re-tests to prove it stayed true.
Proved, not claimed
- ASHRAE 110 tracer gas, at handover
- EN 14175 containment, where specified
- Face velocity re-test, as routine lab safety
The siting problem
Get the hood right and the lab wrong, and it still will not contain.
A hood is proved on a bench with the room held still. It is then used in a room where doors swing, people walk past and air falls out of the ceiling. Every one of those is a cross draft at the sash, and a cross draft at the sash is contamination coming back out.
- Face velocity at the sash
- 0.3 to 0.5 m/s
- Lost to one door swing
- 1 to 2 s
- Clear floor a sash wants
- 1.5 m
Which type does your lab need?
Four shapes cover almost every laboratory. Start from the chemistry and the building, not from the catalogue.
The right answer depends on the chemistry, the building and whether external ducting already exists. A ductless hood is not automatically the easy choice, because its filters have to match the chemistry. The full ductless against ducted trade-off sits on the ductless fume hood page. Ductless fume hoods
Where the hoods go: three hoods in one laboratory
A hood kept away from doors, walkways and supply air diffusers contains far better. Cross drafts at the sash pull contamination back out. Where a hood sits is a containment decision, not just a layout one.
FIG. 01 · Plan view · four siting rules
- 01
A hood facing a doorway
Every time the door swings inward it pushes a wash of corridor air across the room. The hood opposite takes that wash straight on the sash, and for a second or two its face velocity is gone.
Move the door, or move the hood, so the swing arc and the sash never line up.
- 02
A hood beside a walkway
A person walking past at normal pace drags a wake of the same order as the air the hood is pulling in, roughly 0.3 to 0.5 m/s. The wake reaches into the opening and lifts what is inside back out.
Set the aisle back so about 1.5 m of floor in front of the sash is out of the traffic route.
- 03
A hood under a supply diffuser
Supply air falls out of the ceiling, hits the floor and spreads. A diffuser over a hood face turns that spread into a downward push on the very air the hood is trying to draw in.
Relocate the diffuser over the aisle, at low velocity, so no throw lands on a sash.
- 04
Two hoods facing each other
Opposed faces across a narrow room compete for the same make-up air. Each one starves the other, and the room between them never settles.
Group the run on one wall and keep the opposite wall free of hood faces.
- Built as drawn
- Air into the sash
- Disturbed air
- Corrected position
FIG. 01One laboratory, three hoods on one wall, and the three disturbances that decide whether they contain. The loop runs one disturbance at a time: the door swings and washes hood 01, somebody walks the aisle past hood 02, then the ceiling diffuser pushes down on hood 03. At rest the drawing holds all three, fully formed and labelled.
- 01
A hood facing a doorway
Every time the door swings inward it pushes a wash of corridor air across the room. The hood opposite takes that wash straight on the sash, and for a second or two its face velocity is gone.
Move the door, or move the hood, so the swing arc and the sash never line up.
- 02
A hood beside a walkway
A person walking past at normal pace drags a wake of the same order as the air the hood is pulling in, roughly 0.3 to 0.5 m/s. The wake reaches into the opening and lifts what is inside back out.
Set the aisle back so about 1.5 m of floor in front of the sash is out of the traffic route.
- 03
A hood under a supply diffuser
Supply air falls out of the ceiling, hits the floor and spreads. A diffuser over a hood face turns that spread into a downward push on the very air the hood is trying to draw in.
Relocate the diffuser over the aisle, at low velocity, so no throw lands on a sash.
- 04
Two hoods facing each other
Opposed faces across a narrow room compete for the same make-up air. Each one starves the other, and the room between them never settles.
Group the run on one wall and keep the opposite wall free of hood faces.
The drawing above is one laboratory, 8.0 by 4.3 m, with three hoods on the same wall run. Each hood is drawn where a layout would casually put it, with the air that actually forms around it, and with the correction beside it. Nothing in it is exotic. It is the room most Indian labs already have.
Three of these four rules are fixed on the drawing board and cost nothing. The fourth, the make-up air, is the one that has to be engineered, because every hood in the room pulls on the same supply.
Sizing, siting and fitting hoods into the lab
Specifying for a laboratory is more than picking one box, and it is the part most buy-a-hood enquiries miss. It is making several hoods, the benches and the room's air work together. Here is what a credible supplier asks you.
- 01
Sets the material
The chemistry
What is used, how volatile or corrosive is it, and in what volumes? The answer sets the material and settles ducted against ductless.
- 02
1.2 / 1.5 / 1.8 m
Bench width and apparatus
Standard widths run roughly 1.2, 1.5 and 1.8 m. Tall rigs may need a walk-in instead.
- 03
See FIG. 01
Siting in the room
Where each hood lands is settled on the layout, against the doors, the walkways and the supply air diffusers around it. FIG. 01 above draws the four rules and the correction for each.
- 04
CPCB discharge
Ducting, exhaust fans and make-up air
You need a safe external discharge route, exhaust fans sized to the hoods, and HVAC that can supply the make-up air those hoods will pull.
- 05
One shared exhaust
Multi-hood balance
Several hoods on one lab exhaust have to be balanced, so opening or closing one never starves the others. This is where lab ventilation engineering, rather than catalogue picking, decides whether the lab actually works.
- 06
Alarm as standard
Services and monitoring
Gas, water, power and drainage inside the hood. An airflow monitor and alarm. The containment standard you will test against.
FIG. 02What a lab ventilation engineer asks before quoting a hood. Six answers decide the material, the fan and the layout.
Sizing and services ledger
What that turns into on a specification sheet, before anybody quotes anything:
- Standard widths
- 1.2 m, 1.5 m and 1.8 m, with walk-in for tall apparatus
- Face velocity
- 0.3 to 0.5 m/s (60 to 100 fpm) across the sash, monitored and alarmed
- Clear floor at the face
- About 1.5 m kept out of the traffic route, per ANSI/AIHA Z9.5 practice
- Sash
- Safety glass, with the tested working height marked on the frame
- Liner and worktop
- Epoxy coated steel or polypropylene liner, phenolic resin or ceramic worktop
- Exhaust
- Blower sized to face velocity, sash opening and duct run, discharged clear of air intakes
- Services inside
- Gas, water, power and drainage, with the controls reachable from outside the sash
- Monitoring
- Airflow monitor with an audible and a visible alarm at the working position
Laboratory fume hood manufacturers in India: what to look for
Search for a laboratory fume hood manufacturer in India, or for laboratory fume hood for sale or supply, and you mostly get lab furniture suppliers and marketplaces.
To be plain about it: a fume hood is lab furniture. It is also, fundamentally, a ventilation device. So the strongest outcome comes from a supplier who can engineer the exhaust, make-up air and room pressure around it, not only fabricate the box. That is the lens we bring.
Fabtech Cleanrooms is a cleanroom and lab engineering manufacturer. We design, build and validate controlled labs across India.
We supply and integrate fume hoods, specified as part of that lab ventilation design, both standalone and inside a turnkey lab. What a hood costs is quoted per requirement. Fume hood price
Send us your chemistry and bench layout, we will size the hoods and the airflow with you.
Five questions that separate a supplier from a box seller
- 01
Who sizes the exhaust fan, and against which sash opening?
- 02
Where does the make-up air come from, and at what velocity does it arrive?
- 03
How will several hoods on one exhaust stay balanced when one sash closes?
- 04
Which containment test runs at handover, and who witnesses it?
- 05
What happens to room pressure when every hood in the lab runs at once?
Standards and validation
A hood is only trustworthy on the day somebody measures it. These are the documents that define the measurement, and the routine that keeps it honest.
| Standard or check | What it covers | What it applies to |
|---|---|---|
| ASHRAE 110 | Tracer gas containment test proving the hood keeps fumes off the operator | The hood, at handover |
| EN 14175 | Fume cupboard type, on-site and containment tests, often referenced on Indian lab projects | The hood |
| ANSI/AIHA Z9.5 | Laboratory ventilation practice: face velocity, exhaust and make-up air | The lab as a system |
| Periodic re-tests | Face velocity testing and airflow monitor verification, as routine lab safety | The hood, in service |
| CPCB limits | What the lab's exhaust discharge has to meet | The discharge |
| Schedule M | One of the codes that qualifies the classified room the hood stands in, not the hood | The room |
FIG. 03Test regime confirmed per project scope.
The last row deserves plain words, because it trips people up. Inside a classified pharma or QC lab, the room itself is designed to ISO 14644. The grade your regulator sets, under EU-GMP Annex 1, then qualifies that room. Neither says anything about the hood. The hood still has to earn its own test file.
The room and the hood are two separate files
A room qualified to ISO 14644 with an EU-GMP grade against its name says nothing about the containment of the hood standing in it. Ask for both records, and check the dates on both.
How Fabtech approaches laboratory fume hoods
Fabtech specifies, supplies, installs and validates laboratory fume hoods as part of the lab ventilation design. What we add is the whole-lab view.
In practice that means three things. We match each hood to its chemistry and size the exhaust fans and make-up air around it. We site and balance several hoods so the room contains in daily use. Then we prove it against ASHRAE 110.
Where the hazard is biological rather than chemical, the right enclosure is the biosafety cabinet, which Fabtech builds in-house.
Turnkey cleanroom and lab solutions Cleanrooms and labs for pharmaceuticals
Fabtech has designed and built controlled pharma and research labs across India, among them Ajanta Pharma, Desano and BARC. That is exactly the lab ventilation and contamination control engineering a fume hood lives inside.
- Ajanta PharmaPharmaceutical manufacturing, Aurangabad
- DesanoPharmaceutical facility, Bangalore
- BARCResearch and hospital project
A named laboratory fume hood project reference is available on request.
Laboratory fume hoods, common questions
A laboratory fume hood is used to handle chemicals that give off harmful vapours, gases or dust. It pulls air away from the operator, then exhausts or filters it. That protects the person while they work. It is the bench's primary engineering control.
Three: containing toxic or odorous fumes during chemical reactions, protecting operators who handle corrosive or volatile solvents, and capturing dusts or aerosols during sample preparation. In each case the hood pulls the contamination away, then exhausts or filters it.
Four main types. Ducted or conventional hoods exhaust outside. Ductless or recirculating hoods carbon filter the air and return it to the room. Acid and corrosive hoods are built in polypropylene. Walk-in hoods take tall apparatus. The type plates on this page set out which suits which lab.
Match it to the chemistry, the apparatus and the bench. Standard widths are around 1.2 to 1.8 m, with walk-in options for tall rigs. But ducting availability, exhaust fan capacity and make-up air decide as much as width does.
Away from the door, out of the main walkway and not under a supply air diffuser. Each of those puts a cross draft across the sash of the same order as the air the hood is pulling in, which is how contamination gets back out. Two hoods facing each other across a narrow room is the other placement to avoid, because they compete for the same make-up air.
One sized to the hood's face velocity, the sash opening and the duct run. On a multi-hood lab it also has to be balanced across every hood, so opening one never starves another. That makes it an engineering calculation, not a catalogue pick.
A fume hood protects the operator from chemical fumes by exhausting them. A biosafety cabinet uses HEPA filtration to protect operator, product and environment from biological hazards. They are not interchangeable.
Both lab furniture makers and cleanroom or lab engineering firms. The engineering-led route adds the exhaust, make-up air and room pressure design around the hood. Fabtech supplies and integrates fume hoods within that lab ventilation design, and manufactures its own biosafety cabinets in-house.
Tell us about your laboratory
Send the chemistry, the bench layout and whether a duct route exists. Our engineers come back with the hoods, the exhaust fans and the make-up air sized together, not a brochure.