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Safety In Cutting With Plasma Arc - 4
THE CUTTING ARC MAY CAUSE BURNS: During the cutting operations,
appropriate masks, filters and protective lenses should be used for protecting the
eyes against the light emitted by the cutting arc and the flying particles. The skin
should be protected using fire-resistant clothing. The people in the vicinity should
be protected by panels made of fireproof materials, they should not look at the
cutting arc directly and must be warned against effects of the arc light.
Even short periods of exposure to the UV rays may cause eye burns called "welding
dazzle". The person affected may not be aware of the "welding dazzle" for hours
after exposure, which can become extremely disturbing in the end and even cause
temporary loss of sight. Normally the eye dazzle is a temporary condition, but long
term exposure of the eyes to the UV rays may result in permanent damages in the
eyes. As protective measures besides not looking at the cutting arc, a protective
cutting mask with appropriate filtering lens should be used.
The following table may be used for selecting the proper filter against plasma
cutting. You can refer to ANSI Z49.1 filtering selections for cutting purposes.
Plasma Cutting
CUTTING SPLASHES MAY CAUSE FIRE OR EXPLOSION: Keep the flammable
materials away from the cutting areas and maintain a fire extinguisher at an easily
accessible place. The splashes and hot materials ejected by arc cutting may fly
around easily even from the narrowest opening. Do not perform any cutting on
any barrel, container or material until making sure that the measures required for
removing the flammable and noxious gases from the environment are taken. Never
operate the machine in places, where flammable gases, vapors or fluids may be
present.
Keep the possibility of fire risk in mind as plasma cutting may produce very high
temperatures.
The cutting arc temperature may reach 5000°C, but heat alone is not a reason for fire
generally. The fire risk is created by the sparks and molten metal particles splashing
around. Such metal splashes may reach ten meters of distance. Therefore, keep the
easily flammable materials away from the cutting environment. Furthermore, make
sure that your work piece does not contact any material that might flame as it heats
up. The materials that might catch fire when heated are divided in to three groups
as fluids (gasoline, oil, paint, thinner, etc.), solids (wood, cardboard, paper etc.) and
gases (acetylene, hydrogen etc.)
Protective Filter Selection Table
Protective
Current Range
(Amper)
(lower limit)
< 20
20 - 40
40 - 60
Protective
Filter
Filter
(recommended)
4
4
5
5
6
6
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