Maintenance; Disassembly Of Front End; General; Dirt Or Contamination - ESAB PT-25 Manuel D'instruction

SECTION 5

5.1 DISASSEMBLY OF FRONT END

WARNING
Make sure power switch on power source is in the OFF
position and primary input power is deenergized.
If the gouging guard or stand-off guide is being used,
remove it by twisting clockwise and pulling it from the
heat shield.
With the torch head in the downward position, unscrew the
heat shield and remove it, allowing the nozzle to remain
inside.
Inspect the nozzle. The orifice should be round at both the
entrance and the exit. Replace the nozzle if the orifice is
oval shaped or is damaged at either the entrance or exit.
The nozzle may have grey to black deposits on the inside
surfaces. They may be cleaned with steel wool but care must
be taken to remove all traces of the steel wool afterward.
Inspect the heat shield. There should be no signs of arcing
anywhere inside the shield. The outer insulating jacket
should not be severely charred or worn. Replace the shield
if any of the above damage is found.
Inspect the electrode. If it has a pit more than 2mm deep at
its center, replace it. Remove the electrode by unscrewing it
from the electrode holder assembly. After prolonged high
current use, the electrode may require the aid of pliers for
removal. (Do not use pliers for installation).
Inspect the swirl baffle. If any signs of arcing are found,
replace it. The faces of the swirl baffle must be kept clean
where they contact the torch insulator and nozzle. Dirt or
grit on these faces will affect torch performance.
Inspect the electrode holder. Replace it if it shows signs of
arcing or if the electrode threads are galled.
Inspect the o-ring 0558000734 (344019). If it is worn or
damaged, replace it. If it is dry, lubricate it with a thin film
of silicone lubricant 0558000443 (17672). Use just enough
lubricant to make the o-ring appear wet or shiny but do
not leave clumps of excess lubricant.
After all of the front end parts have been inspected and
replaced as needed, reassemble the torch as described in
the section "Assembling Front End Parts".

5.2 GENERAL

Periodically check the heat shield, electrode holder as-
sembly and swirl baffle. If any of these parts are damaged
or excessively worn, replace them.
Check the torch o-ring daily. If the o-ring has nicks, cuts or
other damage, replace it. If it is dry, lubricate it with a thin
film of silicone lubricant. If no drag, caused by the o-ring, is
felt when installing the heat shield, replace the o-ring.
The torch cable sleeving should be inspected periodically.
If any damage to the sleeving is found, inspect the torch
power and pilot arc cables for damage. If gas leaks or
damage of any kind are found, replace the components
in question.

5.3 DIRT OR CONTAMINATION

Dirt or other contamination can cause premature failure
of the PT-25 torch through internal arcing. To avoid this,
do the following:
1. Insure that clean, dry, oil-free air is used for plasma
and/or cooling gas.
2. Avoid excessive use of the silicone o-ring grease on
the torch o-ring. A thin film is sufficient.
3. Wipe the torch body insulator clean with a cloth before
installing each fresh set of consumables. The ability of
the insulator to resist arc tracking over its surface is
reduced when dirt or other contamination is allowed
to collect there.
4. When the torch is not in use, store it with a full set of
front end parts installed. This will prevent dirt from
collecting in the torch and will help protect the torch
head if it is accidentally dropped.
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MAINTENANCE