The Safety of work with the laboratory fume hoods
 General purpose: prevent exposure to toxic, irritating, or noxious
chemical vapors and gases. A face velocity of 100 feet per minute (fpm)
provides efficient vapor capture while reducing hood turbulence.
• Baffles -- keep the airflow uniform across the
hood opening, thus eliminating dead spots and
optimizing capture efficiency.
• Sash --Airflow across the hood can be adjusted
by sash height to the point where capture of
contaminants is maximized.
• Airfoil -- Preventing the creation of turbulent
eddies that can carry vapors out of the hood. The
space below the bottom airfoil provides source of
room air for the hood to exhaust when the sash is
fully closed.
• Exhaust plenum -- An important engineering
feature, the exhaust plenum helps to distribute
airflow evenly across the hood face.
• Face -- The imaginary plane running between the
bottom of the sash to the work surface. Hood face
velocity is measured across this plane.
References
University of Washington; http://www.ehs.washington.edu/fsofumehoods/fume.shtm
Princeton University; http://web.princeton.edu/sites/ehs/labsafetymanual/sec6b.htm
Waterloo University; http://www.safetyoffice.uwaterloo.ca/hse/fume_hoods/fume_hoods.htm
Colgate University; http://www.colgate.edu/offices/administrative/financeandadministration/environmentalhealthandsafetyoffice
/chemicalhygienelaboratorysafety/chemicalfumehoods
Safe Hood Operating Procedure
 Work with the hood sash partially
or completely closed.
 Move work at least six inches inside the face of
the fume hood. This minimizes the effect of crossdrafts and eddies created by the hood operator or by
occupants walking by the hood. Also, keeping
windows and doors closed will control cross-drafts.
Bad
Good
Best
Safe Hood Operating Procedure
 Avoid overcrowding the fume hood work areas.
Chemicals and equipment not in use should be removed from
the hood to a proper storage cabinet. Large bulky equipment
used in the hood will cause eddies that can be reduced by
making sure there is a 1-2 inch air space on all sides
including the bottom. Avoid using equipment that blocks the
hood sash from closing.
Safe Hood Operating Procedure
Constant volume hood – the volume of air exhausted is constant, regardless of sash height.
Proper positioning of the sash is vital to maintaining the optimum face velocity (100 or 125 fpm).
Too high: lowers face velocity, allowing contaminants to escape from the hood
Too low: results in very high face velocity, excessive turbulence and loss of containment
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Confirm that the hood is operational: switch ‘on’, airflow gauge or ‘flow check ribbon’ hood test data
and optimum sash height - yellow label affixed to the hood face
Maintain operations at least 6" inside the hood face
Lower sash to optimum height: maximized airflow without turbulence (17” in accordance to the
rules in Colgate University)
Keep head out of hood and Keep hands out as much as possible
Keep hood storage to an absolute minimum (Do not use your fume hood as a storage area)
Minimize foot traffic around the chemical hood
Use extreme caution with ignition
Connect all electrical devices outside of the hood to avoid sparks which may ignite a flammable or
explosive chemical
Replace hood components prior to use
When fume hood is not in use, keep sash closed and ensure that all materials are in sealed
containers
Prepare a plan of action in case of an emergency, especially when using extremely hazardous
chemicals or acids, and a flammable or explosive chemical
SAFETY EQUIPMENT
 In case of an emergency, you should know the location
and proper use of all the safety equipment provided in the laboratory.
Always immediately inform the staff of any accident.
the science lab safety equipment, including:
Safety Shower
Eye Wash
Fire Blankets
Fire Extinguishers
Fire Exits
Telephone
First Aid Kit
Hand-washing sink
Master gas shut-off
Master electricity shut-off
Biohazardous waste container
Sharps containers
Broken glass containers
Routine garbage containers
Chemical disposal containers
Laboratory fires
A study of one hundred significant laboratory fires by the National Fire
Protection Association provides some interesting facts:
71% of the fires originated in the laboratories;
56% of the laboratory fires originated between 6 PM and 6 AM;
67% of the fires were caused by:
 electrical equipment (wire and appliances) 21%
 misuse of flammable liquids 20%
 explosions 13%
 gas 7%
 spontaneous ignition 6%
Which kind of extinguisher should I use?
The National Fire Protection Association classifies fires into five general categories (U.S.):
* Class A fires are ordinary materials like burning paper, lumber, cardboard, plastics etc.
* Class B fires involve flammable or combustible liquids such as gasoline, kerosene, and common
organic solvents used in the laboratory.
* Class C fires involve energized electrical equipment, such as appliances, switches, panel boxes,
power tools, hot plates and stirrers. Water can be a dangerous extinguishing medium for class C
fires because of the risk of electrical shock unless a specialized water mist extinguisher is used.
(DO NOT USE WATER)
* Class D fires involve combustible metals, such as magnesium, titanium, potassium and sodium as
well as pyrophoric organometallic reagents such as alkyllithiums, Grignards and diethylzinc. These
materials burn at high temperatures and will react violently with water, air, and/or other
chemicals. Handle with care!! (DO NOT USE WATER)
(*Class K fires are kitchen fires)
Which kind of extinguisher should I use?
Class A fires are those fueled by materials that, when they burn,
leave a residue in the form of ash, such as paper, wood, cloth,
rubber, and certain plastics.
Class B fires involve flammable liquids and gasses, such as
gasoline, paint thinner, kitchen grease, propane, and acetylene.
Class C fires are those that involve energized electrical wiring
or equipment (motors, computers, panel boxes)
Class D fires involve exotic metals, such as magnesium,
sodium, titanium.
Which kind of extinguisher should I use?
http://safety.eas.ualberta.ca/node/46
Summary of Fire extinguishers
Extinguisher type
Class
of Fire
Water
A
Water mist
A
Dry chemical
(powder)
BC - Na or K carbonate
ABC - ammonium
phosphate
A, B, and C
Dry metal powder
Copper agent
NaCl agent
D
Dry sand
D
Carbon dioxide
CO2
B and C
Halotron 1
B and C
Hydrofluorocarbons
HFC - 236fa and fe - 36TM
B and C
Examples of Fire type
Distinguising Features
ordinary materials, paper,
not recommended for lab or electrical fires; waterwood, plastics,cardboard
logged debris
etc...
Hospital environments,
Misting nozzle provide safety from electrical shock and
books,clean-rooms, MRI
reduce scattering of burning material
and NMR rooms
Combustible liquids,
laboratory solvents etc...
Overlaying powder reduces re-ignition
Metal and lithium alloy
Powder cling to vertical and 3-D surfaces (Cu).
fires (Cu)
Cakes and forms crust over surface - excludes air,
Mg, Na, K, Uranium and Al
dissipates heat (NaCl).
fires (NaCl)
Electrical etc...
Smother embers
Flammable solvents,
electrically charged
Leaves no harmful residue, but may re-ignite with class
equipment and appliances,
A fires
tools, switches etc...
As for carbon dioxide. Ideal
for computer rooms, clean No thermal or static shock,non-conducting, discharges
rooms, electronics
as "clean agent" liquid and has high visibility
environments etc...
To replace Halotron types.
"Cleanguard" zero-ozone depleting
http://delloyd.50megs.com/hazard/fire.html
Summary of Fire extinguishers
Extinguisher type
Class
of Fire
Water
A
Water mist
A
Dry chemical
(powder)
BC - Na or K carbonate
ABC - ammonium
phosphate
A, B, and C
Dry metal powder
Copper agent
NaCl agent
D
Dry sand
D
Carbon dioxide
CO2
B and C
Halotron 1
B and C
Hydrofluorocarbons
HFC - 236fa and fe - 36TM
B and C
Examples of Fire type
Distinguising Features
ordinary materials, paper,
not recommended for lab or electrical fires; waterwood, plastics,cardboard
logged debris
etc...
Hospital environments,
Misting nozzle provide safety from electrical shock and
books,clean-rooms, MRI
reduce scattering of burning material
and NMR rooms
Combustible liquids,
laboratory solvents etc...
Overlaying powder reduces re-ignition
Metal and lithium alloy
Powder cling to vertical and 3-D surfaces (Cu).
fires (Cu)
Cakes and forms crust over surface - excludes air,
Mg, Na, K, Uranium and Al
dissipates heat (NaCl).
fires (NaCl)
Electrical etc...
Smother embers
Flammable solvents,
*Carbon
extinguishers
are suitable
for many
electrically dioxide
charged fire
Leaves
no harmful residue,
but may re-ignite
with of
class
equipment
and
appliances,
A
fires
the potential fire hazards in the general chemistry laboratories.
tools, switches etc...
As for carbon dioxide. Ideal
for computer rooms, clean No thermal or static shock,non-conducting, discharges
rooms, electronics
as "clean agent" liquid and has high visibility
environments etc...
To replace Halotron types.
"Cleanguard" zero-ozone depleting
http://delloyd.50megs.com/hazard/fire.html
How to use a Fire extinguisher
 In the event of a fire, evacuate the area, close all doors, call for help,
and sound local alarms.
 If you attempt to extinguish it, keep your back to an exit from the laboratory,
do not allow yourself to become trapped or cornered in the lab.
(2) Pull out
locking key.
(1) Aim nozzle
at base of fire.
(3) Squeeze
handles.
How to use a Fire blanket
In case of a clothing fire, a fire blanket
should be used.
Remove the fire blanket from its
container using the straps.
Wrap it around the person to
completely cover the person and
smother the fire.
How to respond to an Emergency
Clarkson University
268-6400
Emergency Number (after working hours)
268-6439
Campus Safety
268-6666
Fire Dept
9-265-3311
Hospital
9-265-3300/3304/5720
Police
9-265-2121/2122
Rescue Squad
911
(Numbers are located near the each lab exit door)