Arc Welding Helmets and Lenses
An electric arc creates ultraviolet and infrared
rays. These light rays are harmful to the eyes and
cause burns, like sunburn, on bare skin. A welder
should cover all bare skin areas while welding.
An arc-welding helmet serves several purposes. It
shields the face and neck from the harmful rays and
protects these areas from molten metal that may spatter
from the weld area. The filter lens and cover plate are
also held by the helmet. A #10–#14 filter lens should
be used for SMAW. A darker lens is required as the
electrode diameter increases. See Figure 5-21. Filter
lenses must conform to the American National
Standards Institute standard Z87.1, which covers the
requirements for welding eye protection.
Many filter lenses are auto-darkening. When there
is no arc, an auto-darkening lens allows you to view
the weld area and position the electrode. The auto-
darkening lens senses the arc and immediately
(1/12,000th to faster than 1/20,000th of a second or
faster) darkens to the preset lens shade number. Many
auto-darkening lenses are variable and can be set to
different shade numbers.
Some welders use a fixed shade lens. When weld-
ing, the helmet is flipped down over the face with a nod
of the head. When welding is completed, the helmet is
lifted up. Figure 5-22 shows both types of helmets.
Clear plastic or glass cover plates protect the filter
lens from arc spatter. Always use cover plates. One is
used in front of the filter lens and one behind the fil-
ter lens. Filter lenses and especially auto-darkening
filter lenses are more expensive than cover plates and
should be protected. Replace cover plates regularly
when they get scratched or speckled with spatter.
Filter lenses and cover plates are available in two
sizes: 2″ × 4 1/4″ (51 mm × 108 mm) and 4 1/2″ × 5 1/4″
(114 mm × 133 mm). An arc-welding helmet can be
adjusted for various head sizes. Adjustable screws
secure the headband to the helmet. These screws
should be tight enough to prevent the helmet from
falling down when it is raised. However, the helmet
should fall into position over the face when the
welder’s head is nodded.
Welding Technology Fundamentals 60
Application
Lens Shade
Number
SMAW (Shielded metal arc welding)
Up to 5/32 in. electrodes
3/16 - 1/4 in. electrodes
5/16 - 3/8 in. electrodes
GMAW (Gas metal arc welding)
(nonferrous)
Up to 5/32 in. electrodes
GMAW (Gas metal arc welding)
(ferrous)
1/16 - 5/32 in. electrodes
GTAW (Gas tungsten arc welding)
10
12
14
11
12
10 to 14
Figure 5-21. The suggested filter lens shade numbers for various
arc welding applications.
Figure 5-22. A—A fiberglass helmet with a large passive or
fixed shade. B—The auto-darkening filter lens in this helmet
has a variable shade setting. (Jackson Safety, Inc.)
A
B