Liquid chromatography using flammable organic solvents as mobile phase requires proper care
against
fire,
explosion, etc. Pakcularly, among various possible accidents, those caused by static
electricity are difficult to anticipate, and tend to occur only with unexpected conditions which
often make countermeasures insufficient.
At a site where preparative liquid chromatography is practiced, a large amount of flammable
substances may be used. Therefore, once an accident happens, it could lead to tremendous
damage.
The mechanism of accident caused by static electrical discharge and preventive measures are
described below. Take due care in safety measures in handling of equipment.
1.
Mechanism
of
Static Electrical Discharge Accident (Example)
Accidents caused by static electricity take place through the following processes.
When liquid is fed at high speed through a small
-
diameter
tube like the pipe of a liquid chromatograph, static electrical
charge occurs by friction between solid and liquid
as
shown in
Fig.
1.
Occurrence
of
Static
Electricity
1
$
-
Flowing liquid
A
Solid
body
A
:
Electric charge
moving with
flowing liquid
B
:
Electric charge
being fixed
to
the
solid surface.
Fig.
1
Occurrence
of
Static Electricity by Friction between Solid and Liquid
Charging and storage
of
static electricity
t
1
Energy release by
1
I
discharge
I
3.
Ignition
of
combustible
substances
f
When the charged liquid is collected in an insulated vessel,
the static charge accumulates gradually, and the voltage can
easily reach
a
few kilovolts.
If
some other conductive object
is
brought near the vessel,
electricity is discharged at a certain distance from the vessel
releasing heat energy.
If flammable gas of sufficient concentration exists nearby,
ignition is caused by this energy.
To Next Page
Loading...