Safety Interlocks; Setup For Cutting; Holding The Torch - Century Tool 118-009 User Manual

The 20 Amp plasma arc cutters have a duty cycle rating
of 20% meaning that out of 10 minutes, you may cut for
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two minutes, but must allow the cutter to cool for eight
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minutes.
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SAFETY INTERLOCKS

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When air pressure is not sufficient to blow the electrode
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back from the nozzle, current will not be allowed to the
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torch for cutting. Some common reasons for low air
pressure are:
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1. The compressed air source pressure or the air
regulator on the cutter is set too low.
2. The consumable parts at the end of the torch are
not installed at all or not installed properly.
3. The O-ring needs replacing.
4. Any filter being used with the cutter is plugged and
needs to have a new filter element installed.
A thermal switch is also provided in the cutter to prevent
overheating. Overheating is normally caused by
exceeding the cutter duty cycle rating, or holding the
torch more than 1/6 inch from the workpiece. If the
thermal switch should shut the cutter off, wait about ten
minutes. The thermal switch will reset automatically
and cutting power will be restored. Cutting materials
without providing a ground to the workpiece will add
heat to the internal components causing the duty cycle
to be less than the listed rating. Whenever possible,
always provide a solid ground to the workpiece.

SETUP FOR CUTTING

1. Begin with the POWER switch OFF and the
power cord unplugged from the ac power source.
2. Check to make sure that all consumable torch
parts are in good condition and properly
assembled on the end of the torch. Correct as
needed.
3. Select the proper cutting nozzle for the amperage
setting selected. For 50 Amp cutters ONLY: in the
30 amp setting, use the nozzle without the
identifying line (Figure 11). For 40 and 50 amp
settings, use the nozzle with the line.
4. Connect the ground clamp to the workpiece
making sure that the connection site is clean and
free of dirt, oil, rust, scale, and paint.
WARNING
PLASMA RAYS CAN INJURE EYES AND BURN
SKIN!
• Do not look at an electric arc without proper protection.
A cutting arc is extremely bright and intense and, with
inadequate or no eye protection, the retina can be
burned, leaving a permanent dark spot in the field of
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vision. A shield or helmet with a number 8 shade filter
lens (minimum) must be used.
• Wear protective clothing and welding gloves. The
intense light of the cutting arc can burn the skin in
much the same way as the sun. The cutting arc is an
open flame and will burn exposed flesh.
Note: The torch may cut without having the ground
clamp connected to the workpiece. But cutting
without grounding the workpiece will add heat
to the plasma cutter internal componentse and
may cause damage to the unit. The additional
heat will cause the duty cycle to be lower. The
cutter will perform much better and
consumables will last longer when the cutter
ground is properly connected to the workpiece.
5. Plug power cord into the ac power source
receptacle.
6. Set the POWER switch ON.
7. Set the mode switch in SETUP and allow the air to
flow for two to three minutes, purging the air lines
of condensation and contaminants. While the air
is flowing, adjust the regulator on the cutter to 65
psi.
Note: IMPORTANT! Selecting the proper air
pressure setting is critical. An air pressure
setting that is too low will result in shorter
consumable life or the failure of the arc to start
at all. A setting that provides too much air
pressure will cause the arc to blow out while
cutting. At pressures lower than about 55 psi, a
safety interlock in the cutter will shut off the
cutter output current. A special tune-in
procedure is provided later in these instructions
to help you determine the air pressure setting
that works best with your cutter.
8. Set the mode switch to RUN. The plasma arc
cutter is now ready for use.
WARNING
PLASMA ARC CUTTERS CAN CAUSE
SERIOUS BURN INJURIES
Make certain the POWER switch is OFF before setting
the cutting torch down. This will prevent the cutting
torch from accidentally triggering when it is not being
held. If the trigger were to be bumped, in any way,
while not being held, a plasma arc could accidentally
start. Serious PERSONAL INJURY to you or
bystanders in the cutting area could be the result.
Such an incident could also result in property damage
due to fire.

HOLDING THE TORCH

1. You may hold the torch with either one or two
hands. The object is to be comfortable and steady
with the torch.