HAZARDS
The main hazards from the use of
inflammable liquids are fire and explosion, involving either the liquid or the
vapour given off from the liquid. Fires or explosions are likely to occur
when vapours or liquids are released into areas where there may be an
ignition source or when an ignition source is introduced into an area where
inflammable liquids are being used.
Inflammable liquids can pose a health
hazard if they are ingested, come into contact with skin or eyes or if their
vapours are inhaled.
CONTROL
The usual way to control the
inflammable
vapours arising from spraying processes is to use a ventilated spraybooth or
enclosure. Its purpose is to:
-
prevent the escape of vapours into
the workplace
-
prevent contamination of the
workplace by overspray
-
protect the health of workers
A spraybooth or enclosure should be of
half-hour fire-resisting construction. If spraying is carried out in a
partial enclosure, work area or a spray space, then it should be fire
separated from adjoining rooms.
The purpose of ventilation is to:
-
draw overspray away from the operator
-
control inflammable and hazardous
vapours
-
collect vapours, droplets and solid
particles
-
filter or wash the air before it is
discharged
The ventilation rate varies
dependant upon the design of spraybooth. A minimum average air velocity of
0.7m/s at the front of open-fronted booths and enclosures is recommended.
If the sprayer works inside a side-draught booth or enclosure, the minimum
average air velocity where the sprayer stands should be not less than 0.5
m/s with a minimum measured value of 0.4 m/s. Where a sprayer works inside
a down-draught booth or enclosure, air velocity (measured at points around a
typical article to be sprayed) should average 0.4 m/s with a minimum
measured value of 0.3 m/s.
Ignition sources should be kept out of
spraying areas at all times. Even when spraying is not taking place,
inflammable residues, contaminated materials, drying and cleaning operations
may still present a fire risk.
There are three classes of hazardous
area or zone: zone 0, zone 1 and zone 2. A zone is an area around a
process or activity where a inflammable atmosphere may be present. For more
detail on this, refer to section on Atex.
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