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B.
Torch Gas Valve
Operation (If Applicable)
The
gas
valve allows gas flow control
at
the torch. A
one-
half
turn
counterclockwise opens the gas
valve,
and
a
one-half
turn
clockwise closes the
valve.
The
gas
valve allows control of gas
postflow
time,
or
the
length
of time gas flows after the
arc
is
extinguished.
In
sufficient gas
postflow
results
in
an
oxidized
(black)
elec
trode surface. If
an
oxidized electrode
were
used,
the
black surface would contaminate the weld and
cause
poor
arc
direction.
IMPORTANT:
As
a
general
rule,
allow 10 seconds of
gas
postflow
time per 100 amperes of weld current be
fore
closing
valve.
4-3.
POWER CABLE CONNECTION
(Figures
4-1
Thru
4-3)
a
WARNING: ELECTRIC SHOCK
can
kill.
Do
not touch live electrical
parts.
Shut down
welding
power
source,
and dis
connect
in
put
power
employing lockout/tag
ging procedures
before
installing
torch.
Lockout/tagging procedures
consist of
pad
locking
line disconnect switch in open
position,
removing
fuses from fuse
box,
or
shutting
off
and
red-tagging
circuit breaker
or
other discon
necting
device.
The power cable is
part
of the
high
flex cable
assembly.
For connection of both power cable and gas hose
to
power cable
adapter,
see
Section
4-2A.
Connect
power cable
adapter
to weld
output
terminal
(see Figures
4-2
and
4-3).
SECTION
5
SEQUENCE OF OPERATION
a
WARNING: ELECTRIC SHOCK
can
kill.
Do
not
touch live electrical
parts.
Keep
all
covers
and handle in
place
while
operating.
ARC
RAYS, SPARKS,
AND
HOT SURFACES
can
burn eyes and
skin;
NOISE
can
damage
hearing.
Wear
correct
eye,
ear,
and
body protection.
FUMES
AND
GASES
can
seriously
harm
your health.
Keep
your head
out
of the fumes.
Ventilate
to
keep
from
breathing
fumes and
gases.
If ventilation is
inadequate,
use
approved
breathing
device.
HOT
METAL, SPATTER,
AND
SLAG
can
cause
fire and burns.
Watch for fire.
Keep
a
fire
extinguisher nearby,
and know
how
to
use
it.
Do
not
use near
flammable material.
Allow work and
equipment
to
cool before
handling.
MAGNETIC FIELDS FROM HIGH CURRENTS
can
affect
pacemaker operation.
Wearers should consult their doctor before
going
near arc
welding, gouging,
or
spot
weld
ing
operations.
See Section
1
-
Safety
Rules for additional
information.
5-1.
GAS TUNGSTEN ARC WELDING
(GTAW)
1.
Install and
connect
torch
according
to
Section
4.
2.
Make
sure
collet
body,
cup, and all
gas
connec
tions
are
securely tightened.
3.
With
regulator/flowmeter
valve
closed,
open gas
cylinder
valve.
4.
Set power
source
for desired
welding
amperage.
5.
Wear
dry insulating gloves
and
clothing,
and
wear
welding
helmet with proper filter lens
according
to
ANSI
Z49.1.
6.
Energize welding
power
source.
7.
Set gas flow
to
desired level
(requires
open gas
valve).
IMPORTANT:
Purge
gas hose
to
clear hose of
air,
mois
ture,
or
any other contaminants. Allow gas
to
flow
2 to 3
minutes
on new
torch;
5
to
6 seconds
thereafter.
8.
Begin welding.
5-2.
SHUTTING DOWN
1.
Stopwelding.
IMPORTANT: As
a
general
rule,
allow 10 seconds of
gas
postflow
time
per 100 amperes of
weld current be
fore
closing
valve.
2.
Turn
off
welding
power
source.
3.
Turn off the
shielding
gas
at
the
source.
a
WARNING:
HIGH
CONCENTRATION OF
SHIELDING GAS
can
harm health
or
kill.
Shut off gas
supply
when
not in
use.
OM-1558
Page
6
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