Installation; Torch To Power Source Connections; Gas Selection; Operating Parameters - ESAB PT-25 Instruction Manual

SECTION 3

3.1 TORCH TO POWER SOURCE CONNECTIONS

Consult your power source instruction manual for access
to the torch connections.
CAUTION
Make sure the power switch on the console is in the off
position and the primary input power is deenergized.
The PT-25 torch uses a "C" sized left hand thread fitting
for the negative terminal and the plasma gas connection.
Connect this fitting to the corresponding female fitting on
the power source and tighten it firmly with a wrench. After
tightening the fitting, slide the rubber boot on the power
cable over the connection. The "B" sized right hand fitting
is used to make the positive terminal and cooling gas con-
nection. Tighten it firmly as well.
The safety sensor tube plugs into the small bulkhead fitting
or tube union at the power source. Simply push it into the
fitting or union until it is fully seated.
WARNING
The torch front end components are designed to send a
gas pressure signal to the power source when the heat
shield and nozzle are properly installed. This gas pres-
sure operates in conjunction with circuitry provided
in the power source. This patented system provides
a safety interlock preventing the torch from being ac-
cidentally energized with high voltage when the heat
shield is removed and the torch switch is accidentally
closed. Occasionally check this system by removing the
heat shield. Turn on power source. Do NOT touch the
metallic parts on the torch front end. Close the torch
switch and place the electrode in contact with a prop-
erly grounded work piece. If the torch energizes and
arcing occurs between the electrode and work piece,
DO NOT USE. Do NOT tamper with the torch or power
source. Return torch and power source to your ESAB
distributor for repair.
The torch switch connection is made with the 5-pin plug
on the torch switch lead. Insert the plug into the socket
on the power source and twist the locking ring to secure
it in place.

3.2 GAS SELECTION

The PT-25 is a dual gas torch, allowing for one gas to be
used for plasma gas and another to be used for cooling
the torch as well as shielding the cut zone. Recommended
combinations of gases are listed below.
WARNING
Use only those gases listed as approved in this manual.
(See Section 1.2). Do not use Argon or Argon mixtures
as cooling gas in the PT-25 as internal arcing in the torch
head may occur. Do not use oxygen as cooling or plasma
gas as the torch may catch fire.
Air Plasma / Air Cooling
Best overall combination for cut quality, cut speed and
economy on mild steel, stainless steel and aluminum. This
combination causes some surface nitriding at cut face and
some surface oxidation of alloying elements on stainless
steels. Always use clean, dry air. Moisture or oil in the air
supply will reduce torch parts life.
Nitrogen Plasma / Air Cooling
This combination provides improved parts life, especially
for the electrode. Cut speeds will usually be slightly slower
than with air plasma. It creates surface nitriding but provides
cleaner cut face on stainless steels. Nitrogen or CO
substituted for air cooling.
H-35 Plasma / Nitrogen Cooling
This combination gives excellent parts life with minimum
amount of cut surface contamination, providing excellent
weldability. It is most often used for gouging on mild steel,
aluminum, and stainless steel. It gives poor cut quality on
mild steel, good cut quality on aluminum and stainless,
particularly on thicker sizes.
40% Hydrogen - 60% Nitrogen Plasma / Air Cooling
This combination is used on aluminum only for increased
speed and thickness capability. This combination offers no
real advantage on stainless and mild steels.

3.3 OPERATING PARAMETERS

Recommended Gas Pressures
Plasma (Cutting) 4.5 - 5.2 bar
Plasma (Gouging) 2.8 - 3.1 bar
Cooling 4.5 - 5.5 bar
Recommended Stand-off
5 - 13mm
Recommended Current Settings
Air Plasma - 100A maximum
N , Ar- H , N - H Plasma - 150 A maximum
2 2 2 2
Travel Speeds
Travel speeds for the PT-25 are given in the charts
shown in Figures 3.1 and 3.2.
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INSTALLATION

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