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Engineering Control of Hazards
Ventilation
Good ventilation is essential in rooms or areas where epichlorohydrin is
handled to prevent accumulation of concentrations that result in time weighted or ceiling exposures of people
in excess of the designated limits. Controlling to these limits will also
ensure that explosive limits (which are much higher) will be avoided. The
type of ventilation needed will depend upon such factors as temperature,
dead spaces, convection currents, wind direction, etc., which must be
considered by the engineer designing the system in determining equipment
location, type, and capacity. Laboratory work should be done in a hood to
avoid exposure and introduction of vapors into the workroom air. If
mechanical ventilation is used, periodic monitoring should be employed to
assure suitable operations and control.
Air Analysis
Chemical analysis of the air for epichlorohydrin is the work area will give
a measure of the effectiveness of engineering control of the vapors. I may
be used to detect leakage of epichlorohydrin vapors from equipment and to
estimate the order of magnitude of the health hazard and fire hazards, as
well, if the amount escaping is enough to approach the lower explosive limit.
Epichlorohydrin vapor concentration in air near or within the explosive
range (3.8 to 21% by volume in air) is most easily determined by the use of
a standard combustible gas indicator. Measurements meaningful in terms of
health hazard must be made with a procedure having a sensitivity of at
least 1 ppm.
Electrical Equipment
To help ensure safe operation, wiring should be installed in accordance
with Section 500 of the National Electrical Code, NFPA No. 70, Class 1,
Group D, Division 1 or 2, the latter depending on the specific operation
involved in a particular location. Motors, controls, switches, relays,
lights, etc. should be explosion-proof, or as otherwise stated in this
code. No heating apparatus capable of reaching 80% of the autoignition
temperature of 416°C should be used.
Overheating
Automatic temperature controls are recommended for processes where
epichlorohydrin is heated, but even with these, close supervision should be
maintained in the event of control system failure.
Static Electricity (See NFPA No. 77)
Sparks from static electrical discharge can ignite epichlorohydrin vapor
and air mixtures if the epichlorohydrin concentration is within the
explosive limits.
Epichlorohydrin flowing through or being discharged from a line generates
static electricity. All equipment and piping should be continuously bonded
together and then to a ground system.
Before epichlorohydrin is poured or discharged from one metal container to
another, the two vessels shall be bonded and grounded so that the
resistance to ground does not exceed one megohm. All metal surfaces with
which epichlorohydrin comes in contact should be bonded so that the
resistance to ground does not exceed one ohm. Any ground that is adequate
for power circuits or lightning protection is considered adequate for
protection against static electrical discharge. Electrical conductivity
should be checked periodically. Where drive belts are necessary,
conductive belts are recommended. Pulley and drive shafts should be
grounded to avoid accumulation of static electrical charges.
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