Safe Handling Practices for Hexane

January 18, 2011

Hexane is classified under Petroleum Class ‘A’ Category
of the Petroleum Act, 1934. (xxx of 1934) and
the Petroleum Rules, 1976. It is an extremely inflammable
liquid with a low flash point. But, if its properties
are thoroughly understood, and, the following simple
safe handling practices are adhered to, then Hexane
can be handled, stored and used as safely as water.
Though Hexane is not used as a fuel in the process
of solvent extraction, the fact that the vapour given out
by Hexane can burn or explode cannot be overlooked.
Hexane in liquid form does not burn. It is only the
vapour emitted by Hexane that burns or explodes if
the vapour is of correct concentration. Any mixture
which contains lesser than 1.25 % by volume of Hexane
vapour in 98.75 % of air or more than 6.9% of vapour
in 93.1% of air, will not burn or explode.
On account of, its low flash point, low boiling point and
fairly high vapour pressure at normal conditions of
temperature and pressure. Hexane, continuously
generates readymade fuel. The vapour given out by
Hexane, mixed with atmospheric air, thus presents a
potential hazard.
Under normal conditions, fuel in vapour form and combined
with right proportion of air, does not burn by itself, the
mixture needs to come in contact with a source of

ignition. In order to avoid unnecessary fires, source
of ignition should be kept away from Hexane vapour.
Vapour given out by Hexane is nearly three times heavier
than air and hence seeks the lowest available level like
floors, pits, etc.
Hexane vapour displaces oxygen in atmosphere and
hence breathing in such an area can cause asphysixiation.
Liquid Hexane though non-toxic, removes the essential
oil from human skin and renders it dry.

Important Safe Handling Practices Recommended
for Handling, Storing of Hexane:
— Do not use Hexane for cleaning hands and other
parts of the body.
— Before allowing persons to enter Vessels or tanks
or other facilities that have contained Hexane, it
should be first determined whether the area is gas
free and that it is safe for people to enter.
— Vessels, tanks, pipelines and other facilities used
for containing or conveying Hexane should be
periodically inspected to ensure that there are no
leaks through which the liquid or vapour can escape.
— In case of spillage of this product on the floor or
anywhere else, such spillage should be immediately
wiped out before the liquid vapourises. Causes for
the spillage should be corrected. Use of protective
equipment by a person during sweeping up the spills.
— It is desirable to provide ventilation at floor levels
wherever Hexane is handled, stored and used.
— Sources of ignition like open flames, welding arcs
and the like, should be kept away from areas where
Hexane is handled, stored and used.
— Sparks given out at defective electrical contacts can
easily burn or explode Hexane vapour. Maintain in
good repair all electrical devices provided in areas
where Hexane is handled, stored and used.
— Repair work to vessels, tanks or other facilities that
have contained Hexane (especially where the work
involves using facilities that can create a source of
ignition), should be carried out only after these facilities
are freed of Hexane vapour. Such a gas freeing
operation can be accomplished by displacing the
vapour with either water or steam.
— In the event of an occurance of fire during the handling,
storage or usage of Hexane, the quickness with
which the fire is tackled will determine whether or
not the fire situation can be controlled easily. Extinguishment
of such a fire usually incorporates the
principle of starving the fire of air and simultaneously
cutting away further supply of fuel to the fire.
— Use of dry chemical fire extinguishers help to create
an artificial blanket of powder which starves the fire
of air. Chemical foam type extinguishers can also
be used for this purpose. When a large fire occurs,
the fire area should first be isolated and the fire
should than be tackled with the acid of Mechanical
foam.
— Fire fighting i.e. making efforts to extinguish a fire
after it occurs is by far a more difficult task as
compared to the efforts that need to be put in to
prevent occurence of fire. It is for this purpose that
importance should be placed on the fire prevention
aspects during handling, storage and usage of
Hexane.
Static Electricity:
Hexane being an electrically resistive product, generates
electricity during handling. This can create a safety
hazard when the accumulation of charge is sufficient
to result in static sparking of a flammable vapour, which
exists in tanks (even those with floating seals), tank
cars and tank trucks at a loading temperature of -20°C
to + 10°C and for short periods during initial loading
at higher temperatures. Though ambient temperature
is well above those mentioned, yet it is advisable to
take following safety precautions :
— Do not use overhead splash filling.
— Do not agitate with mixers, jet nozzles or by recirculation.
— Avoid water bottoms or other contamination of product
with water as well as entered air in the products
while pumping.
— Endeavour to keep velocities of stocks entering vessels
to a practical minimum. Reduced velocities are particularly
advisable during the start to tank filling until the inlet
nozzle has been well submerged : about 3 feet per
second has been suggested.
— Once the inlet nozzle is well submerged, velocities
of about 10 feet per second are considered acceptable.
— Where filters are used, a minimum hold up time of
30 seconds should be built in the pipe system between
the filter and the receiving vessel.
— Care should be exercised to minimize the chance
of any ungrounded floatable objects finding their way
to the tank. The tank should be inspected at regular
intervals and any free objects which might float removed.
— All gauge floats or other internal appurtenances should
be maintained in electrical continuity with the structure
of the tank. Gauge floats to have become
disconnected should be promptly removed but not
while pumping into the tank.
— No objects such as gauge bods, sample containers,
thermometers, etc. should be lowered into the tank
within a period of 30 minutes after pumping or circulation
within the tank has ceased. No one should
go on to the roof of the tank until 30 minutes relaxation
period has elapsed.
— In the case of floating roof tanks, the floating roof
should not be allowed to rest on its legs.
— All Cone Roof Tanks should have suitable weak
circumferantial roof seams and be equipped with
pressure vacuum vents.

Tank Trucks:
— Tank Trucks should be adequately bonded to the
fill line or nozzle.
— The fill line should extend to the bottom of the tank.
— The rate of flow should be kept low (1 metre per
second) until the end of the fill pipe is well submerged.
Once the nozzle is well submerged, velocities
of 3m per second are acceptable.
— Where filters are used a minimum of 30 seconds
should be built into the piping system between the
filter and the receiving vessel.
— Care should be exercised to avoid floating of ungrounded
objects finding their way to the tanks.
— No objects such as gauge bobs, etc. should be
lowered in the tank within 15 minutes after pumping
has ceased.
— Where filters are used, persons should remain off
the top of the tank car or truck and a safe distance
away while loading is in operation.

Previous post:

Next post: