INSTRUCTIONS for
PT-20AM
MECHANIZED PLASMA ARC CUTTING TORCH
Without Rack, 50-ft., Unshielded..................................P/N 21360
With Rack, Torch Holder, 50-ft., Shielded ....................P/N 21371
With Rack, 50-ft., Shielded...........................................P/N 22057
Without Rack, 50-ft., Shielded......................................P/N 21977
Without Rack, 4-1/2-ft., Shielded...................................P/N 21785*
Without Rack, 17-ft., Shielded.......................................P/N 21786*
* For connecting to plumbing boxes.
These INSTRUCTIONS are for experienced operators. If you are not fully familiar with the principles of operation and safe
practices for arc welding equipment, we urge you to read out booklet, "Precautions and Safe Practices for Arc Welding,
Cutting and Gouging", Form 52-529. Do NOT permit untrained persons to install, operate, or maintain the equipment. Do
NOT attempt to install or operate this equipment until you have read and fully understand these instructions. If you do not
fully understand these instructions, contact your supplier for further information.
torch with minimum downtime (see Table 1 for contents of
each kit):
The plasma arc cutting process employs extremely high
voltages and contact with "live" parts of the torch and
machine must be avoided. Also, the improper use of any
of the gases employed can present a safety hazard. Before
beginning operation with the PT-20AM torch, refer to the
safety precautions listed on page 2 of instruction booklet
packed with your plasma cutting console.
I. INTRODUCTION
The patented PT-20AM is a 100 amp capacity, pilot-arc
mechanized torch (see Fig. 1) available in 6 different versions
listed above. The torch uses clean, dry air as the cut gas for
cutting carbon steel, aluminum, or stainless steel. DO NOT
use oxygen; a hazardous fire may result.
This booklet covers mainly the accessories, maintenance,
and parts information for the PT-20AM torch. For installation
and operating instructions for your cutting package, refer to
appropriate booklet with your console.
II. ACCESSORIES
A. PT-20AM Torch Spare Parts Kits - The following three
spare parts kits are available for maintaining the PT-20AM
50 Amps - P/N 21370
70 Amps - P/N 21369
100 Amps - P/N 21376
Table 1 - Contents of PT-20AM Spare Parts Kits
50 Amp 70 Amp 100 Amp
Description, P/N 21370 21369 21376
Heat Shield (70/100 A), 21326 - 2` 2
Heat Shield (50 A), 21447 2 1 1
Cutting Nozzle (50 A), 21330 5 5 5
Cutting Nozzle (70 A), 21329 - 5 5
Cutting Nozzle (100 A), 21328 - - 5
Electrode, 21150 5 5 5
Electrode**, 0558001617 5** 5** 5**
Electrode Insulator, 21373 1 1 1
Electrode Holder Assy, 21332 1 1 1
Baffle Tube, 21374 1 1 1
Pilot Arc Adaptor, 19497 1 1 1
O-ring, 488157 5 5 5
Lubricant (1 oz.), 17672 1 1 1
Seat/Baffle Wrench, 21375 1 1 1
1/16: Hex-Key Wrench,
93750006 1 1 1
Tool Box, 950272 1 1 1
**For 50Hz Machines
F-15-114-E
January, 2001
Quantity
7 5/8" min. - 14 1/2" max.
5/8" Mounting Stud
17 1/2" With Rack
1 3/8" Dia.
Fig. 1 - Dimensional Data - PT-20AM
Be sure this information reaches the operator.
You can get extra copies through your supplier.
1 3/8" Dia.
13 1/2" Without Rack
III. INSTALLING FRONT END PARTS
Make sure power switch on console is in OFF position and
primary input power is deenergized.
1. The electrode holder assembly (21332) includes the baffle
tube (21374). If the baffle tube becomes damaged, it can be
replaced by threading the damaged tube out of the holder
and threading in the new one. Use the small hex end of the
wrench (21375) in the hex broach on the tube. Tighten the
tube securely but do not overtighten.
2. Install the electrode insulator (21373) onto the electrode
holder assembly (21332) and then thread the electrode
(21150) onto the electrode holder assembly. Assemble the
electrode firmly by hand. Do not use wrenches or pliers.
These three parts together are the electrode assembly.
3. Install the nozzle onto the electrode assembly by inserting
the small shoulder on the electrode insulator into the
nozzle’s rear opening. Place the nozzle and electrode
assembly into the heat shield as shown in Fig 2. If the front
end of the torch is facing down as normally in a setup, the
nozzle and electrode assembly can be stacked in the heat
shield and then assembled to the torch. Be sure to use the
proper heat shield and nozzle combination as noted in Fig.
2.
NOTE:
These parts are NOT interchangeable with origninal PT-20M
Torch. P/Ns 20598 and 20599 are covered by F-15-021.
BAFFLE TUBE - 21374
WRENCH SEAT/
BAFFLE - 21375
4. Apply a thin film of lubricant (17672) to O-ring (488157).
5. Tighten heat shield fully to hold the parts in firm contact with
each other and to the torch head.
IMPORTANT: See Maintenance section.
Follow all instructions in the booklet packed with your unit. DO
NOT install or attempt to operate this torch without following
these instructions.
To connect PT-20AM torch to the console, connect the power
cable of the torch to the ‘‘NEG’’ terminal and pilot arc cable to
the ‘‘POS’’ terminal of the unit using pilot arc adaptor (19497
- supplied with spare parts kit). A separate remote control
switch cable is required for connecting to the switch receptacle
on the console.
The front end of the torch contains a gas flow check valve that
acts in conjunction with the circuitry provided in the power
supply. This patented system provides a safety interlock
preventing the torch from being accidentally energized with
high voltage when the heat shield is removed and the torch
switch is accidentally closed.
NOTE:
Torch body insulator design was changed to eliminate the
need for a replaceable electrode seat. This drawing and parts
list reflects that change. The insulator material color was
changed for indentification of the part revision level.
Brown torch body insulators were used on torches
before 12/99 and do require a separate electrode seat.
Gray torch body insulators indicate there is not a replaceable
electrode seat...
DO NOT ATTEMPT TO REMOVE THE ELECTRODE SEAT
FROM THESE TORCHES AS EQUIPMENT DAMAGE WILL
OCCUR.
ELECTRODE INSULATOR - 21373
ELECTRODE - 21150
ELECTRODE-50Hz - 0558001617
ELECTRODE ASSEMBLY
ELECTRODE HOLDER ASSEMBLY - 21332
(INCLUDES BAFFLE TUBE - 21374)
NOZZLE
100 AMP - 21328
70 AMP - 21329
HEAT SHIELD
70 & 100A (Blue) - 21326
50 Amp (White) - 21447
50 AMP - 21330
Fig. 2 - Front End Assembly
2
TORCH BODY INSULATOR
(Reference,
not replaceable)
O-RING - 488157
CUTTING PARAMETERS FOR THE PT-20AM TORCH
ON CARBON STEEL
Table 2: 100 Amp Data, Nozzle P/N 21328, Heat Shield P/N 21326
Metal
Thickness
(in.) (mm)
0.250 6
0.500 13
0.750 19
1.000 25
1.250 32
1.500 38
Metal
Thickness
(in.) (mm)
0.125 3
0.250 6
0.500 13
0.750 19
1.000 25
1.250 32
Air
Pressure
(psig) (bar)
85 6
85 6
85 6
85 6
85 6
85 6
Stand-off
(in.) (mm)
0.250 6
0.250 6
0.250 6
0.250 6
0.312 8
0.312 8
Arc
Voltage
DC Volts
110
120
125
130
140
145
Pierce
Time
(sec.)
0.1
0.3
1.0
2.75
*N.R.
*N.R.
M ild Ste el
(ipm) (mm/min)
100 2540
45 1143
27 686
15 381
10 254
7 178
Trave l Speed
Aluminum
(ipm) (mm/min)
105 2667
50 1270
35 889
20 508
13 330
10 254
Table 3: 70 Amp Data, Nozzle P/N 21329, Heat Shield P/N 21326
Air
Pre ssure
(psig) (bar)
75 5
75 5
85 6
85 6
85 6
85 6
Stand-off
(in.) (mm)
0.188 5
0.188 5
0.250 6
0.250 6
0.312 8
0.312 8
Arc
Voltage
DC Volts
105
110
115
130
140
155
Pierce
Time
(sec.)
0.1
0.2
0.6
2.3
*NR
*NR
Mild Steel
(ipm) (mm/min)
190 4826
80 2032
30 762
15 381
7 178
5 127
Travel Spee d
Aluminum
(ipm) (mm/min)
180 4572
85 2159
30 762
25 635
12 305
10 254
Stainless
(ipm) (mm/min)
80 2032
30 762
15 381
10 254
7 178
5 127
Stainless
(i pm) ( mm/ mi n)
80 2032
55 762
20 381
8 254
6 152
3 76
Table 4: 40 & 50 Amp Data, Nozzle P/N 21330, Heat Shield P/N 21447
Metal
Thickness
(in.) (mm)
0.063 2
0.125 3
0.188 5
0.250 6
0.375 10
0.500 13
* NR - Indicates piercing is not recommended.
Air
Pressure
(psig ) (bar)
75 5
75 5
85 6
85 6
85 6
85 6
Stand-off
(in.) (mm)
0.125 3
0.125 3
0.125 3
0.188 5
0.250 6
0.312 8
Arc
Voltage
DC Volts
110
110
110
120
130
150
Curr ent
Amp s
3
Arc
40
40
50
50
50
50
Mild Steel
(ipm) (mm/min)
150 3810
100 2540
100 2540
65 1651
40 1016
18 457
Travel Speed
Alumin um
(ipm) (mm/min)
150 3810
105 2667
90 2286
75 1905
30 762
8 2034
Stainless
(ipm) (mm/min)
130 3302
75 1905
50 1270
30 762
8 203
6 76
IV. MAINTENANCE
Before any maintenance is attempted on this torch, make
sure the POWER SWITCH on the console is in the OFF
position and the PRIMARY INPUT POWER is
DEENERGIZED.
A. General
1. The gas flow check valve is part of the safety interlock
and is permanently assembled in the torch head. The
head must be replaced if this valve malfunctions.
2. Periodically check the heat shield, electrode holder
assembly and electrode insulator. Replace if worn or
damaged.
3. Apply a thin film of lubricant P/N 17672 (supplied in
spare parts kit) to the O-ring. Check O-ring for damage
whenever the shield is removed. Replace if necessary.
4. The power and pilot arc cables should be inspected
periodically. If cuts through the protective sheath or if
gas leaks are noted, replace the damaged component.
The torch requires good electrical contact to the electrode
holder. If good contact is not maintained, then the resulting
potential difference may cause internal arcing and possible
torch damage.
ARC TRACKS
ELECTRODE HOLDER ASSEMBLY
B. Dirt or Contamination
Dirt or other contamination in the torch and loose consumable
parts can cause premature failure of the PT-20AM Torch
through internal arcing. To avoid this, users are instructed to
do the following:
1. Insure that clean, dry, or oil-free air is being used.
2. Avoid excessive use of the silicone o-ring grease used
to lubricate 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.
C. Loose Consumables
Tests have shown that with proper use of the torch within the
rated operating conditions (especially arc current and gas flow
rate), the torch consumable parts do not become loose if they
are firmly installed in the first place.
1. Tighten the heat shield fully at each consumable change
or inspection.
D. Damage Caused by Loose Parts and Torch Overheat-
ing.
Arc tracking indicates loose parts. Make sure heat shield is
tightened fully. Check tightness again after a few minutes of
use. Parts damaged by arcing will cause destruction of torch.
Parts damaged by arcing must be replaced.
ELECTRODE INSULATOR
21373
2. Check the consumable tightness at the beginning of
each work shift, even if everything was working normally
at the end of the previous shift.
3. Insure that the torch internal cavity and electrode holder
are clean and free of dust or dirt which would keep the
mating surfaces from having solid contact and that a
contact ring is visible along the cavity wall.
Deformation at this edge indicates
torch overheating. Check gas pressure, gas flow rate and current setting. Deformation leads to loose parts
and internal arcing. Do not operate
torch with a deformed insulator.
4
E. Consumables- Remove and Replace
1. Bring the torch to a position where it is easily accessed
by the machine operator, in its normal vertical position
and at least six (6) inches above the workpiece or the
edge of the water table.
F. Measuring Torch Gas Flows
If low gas flow is suspected of causing poor cutting performance or short consumable life, the flow can be checked by
using Plasma Torch Flow Measuring Kit (P/N 19765). The
kit includes a hand held rotameter (flowmeter) which will
indicate the gas flow rate exiting the torch. The kit also includes
a set of instructions which should be followed exactly to insure
safe and accurate use of the rotameter.
Make sure that the power source has been turned off
and that the power cable has been unplugged at the
wall receptacle before proceeding.
2. Unscrew the heat shield and lower it away from the
torch, allowing the nozzle and electrode assembly to
remain with the shield.
3. Remove the nozzle and electrode assembly from the
shield and inspect for wear. The nozzle orifice should be
round at both the entrance and the exit. If the nozzle
orifice is worn in an oval shape or shows other signs of
damage at either end, it should be replaced. The inside
of the nozzle may have light grey deposits from the
electrode. These may be removed with steel wool but
care must be taken to remove all traces of the steel wool
afterward.
If the electrode has a pit which is more than 1/16 inch
deep at its center, replace it. This is done by unscrewing
the electrode from the electrode holder. Grasp the
electrode holder with the fingers using the two flats and
grasp the electrode between the thumb and finger of the
other hand and twist.
Inspect the electrode insulator and the electrode holder
assembly for signs of damage such as arc tracking or
cracking and replace them if any are found. Insure that
the baffle tube is securely threaded into the electrode
holder, but do not overtighten. Use the small hex end of
the plastic wrench in the spare parts kit.
After installing the electrode insulator onto the electrode
holder assembly, install the electrode by reversing the
procedure used to remove it. Note that firm tightening of
the electrode by hand is sufficient, the use of tools such
as wrenches or pliers is not required or recommended.
4. Inspect the heat shield for signs of damage or wear. The
gas holes inside the shield should not be blocked by
debris, and there should be no signs of arcing anywhere
inside the shield. The outer insulating jacket of the
shield should not be severely charred or eroded. Replace the heat shield if any of the above damage is
found.
5. Inspect the o-ring on the torch. If it shows signs of wear
or damage, replace it. If it is dry, lubricate it with a thin
film of the lubricant supplied with the spare parts kit.
6. Install the nozzle and the electrode assembly into the
heat shield and thread the heat shield onto the torch.
The shield should be tightened fully to insure good
electrical contact for the electrode and the nozzle.
The PT-20AM’s total air flow rate should be 325 cfh minimum
with any nozzle at 75 psig.
G. Removal and Replacement of the Torch Body
(Refer to Fig. 3)
1. Cut and remove the shrink wrap at the back end of the
torch handle. Unscrew the handle from the torch body
and slide it back onto the torch cable assembly in order
to expose the torch connections.
2. Remove the electrical tape which secures the short
piece of vinyl tubing on the pilot arc cable. Slide the
tubing away from the torch and onto the pilot arc cable
to expose the pilot arc connector.
3. Use the 1/16" Allen Wrench supplied in the spare parts
kit to loosen the pilot arc connector set screw closest to
the torch body, being careful not to totally remove the
screw. Slip the torch’s pilot arc lead out of the connector.
4. Unscrew the power cable fitting from the torch’s power
lead using a 7/16" open-end wrench and remove the
torch body.
5. Connect the pilot arc cable and the power cable to the
new torch body’s pilot arc lead and power lead by
reversing the steps taken to disconnect them. Tighten
the pilot arc connector set screw fitting firmly but do not
overtighten. Torque the power fitting to 20 lb.-in.
6. Slide the vinyl tubing forward to cover the pilot arc
connector and secure in place with electrical tape.
7. Slide the handle forward and thread it firmly onto the
torch body.
8. Slide the new piece of shrink tube over the torch handle
and shrink in place over the handle’s end and the cable
sheath.
H. Removal and Replacement of the Torch Cables
(Refer to Fig. 3)
1. Disconnect the torch cable assembly from the power
source. Refer to your power source instruction booklet
for detailed instructions.
2. Remove the torch body and handle from the cable
assembly as described in the previous section.
3. Lay the cable assembly on the floor and stretch it out
completely. This should be done in an area that is
approximately 1-1/2 times as long as the cable assembly.
5
4. Using a piece of cord or sturdy twine about 1/2 the length
of the torch cables, secure one end of the cord around
the cables at the torch end and secure the other end of
the cord to a stationary object.
5. Remove the tape securing the cable sheath to the
cables at both ends.
6. Secure the torch cables at the power source end and
pull the sheath completely off the cables and onto the
cord used in step 4.
10. Secure the sheath to the cables using electrical tape at
both ends.
11. Remove the torch body (temporarily installed in step 9)
from the cables and slide the handle over the cables and
cable sheath. Install the vinyl tube over the pilot arc
cable.
12. Reconnect the torch body to the cables as described in
the previous section and reinstall the torch handle onto
the torch body.
13. Reconnect the torch cables to the power source.
7. Untie the cord from the cables and replace the damaged
cable or cables. Be sure to retain the vinyl tube used to
insulate the pilot arc connector.
8. Resecure the torch ends of the cables with the cord, and
pull the cable sheath back off of the cord and onto the
cables.
9. Untie the cord from the cables and temporarily secure
the torch body to the cable connections.
H.F. CONNECTOR - 17974
(2) SETSCREW #6/32 x 3/16
Insulate with vinyl tubing (Supplied) and secure w/electrical tape.
SHEATH (50 FT.) - 995826
SHIELD SHROUD (17-FT) - 21788
SHIELD SHROUD (4 1/2-FT) - 22330
1 3/8"
Wrap with electrical
tape as shown.
POWER CABLE ASSY. (50 FT.) - 20621
POWER CABLE ASSY. (17 FT.) - 21794
POWER CABLE ASSY. (4 1/2 FT.) - 21793
V. REPLACEMENT PARTS
Replacement parts are keyed in Fig. 3 and 4. Order replacement parts by part number and part name as shown on the
illustrations. DO NOT order by part number alone. Parts may
be ordered from your ESAB welding equipment distributor or
from ESAB Welding & Cutting Products, Customer Service
Department, Florence, SC.
HANDLE W/O RACK - 948177 (21360, 21977)
HANDLE/BRASS SLEEVE ASS'Y - 22329 (21785, 21786)
HANDLE W/RACK- 999482 includes:
RACK ASSY. - 49V29
LOCK RING - 57N70
7/8"-14 LH
BODY ASSY. - 21359
includes:O-RING - 488157
See Fig. 2
PILOT ARC CABLE ASSY. (50 FT.) - 948163
PILOT ARC CABLE ASSY. (17 FT.) - 21792
PILOT ARC CABLE ASSY. (4 1/2 FT.) - 21791
Fig. 3 - PT-20AM Torch Assembly:
Without Rack, 50-ft., Unshielded (illustrated) ........... P/N 21360
With Rack, Torch Holder, 50-ft., Shielded ................... P/N 21371
With Rack, 50-ft., Shielded............................................ P/N 22057
Without Rack, 50-ft., Shielded ...................................... P/N 21977
Without Rack, 4-1/2-ft., Shielded.................................... P/N 21785*
Without Rack, 17-ft., Shielded........................................ P/N 21786*
* For connecting to plumbing boxes.
6
KNOB - 31W18
WASHER - 1/2"
HOLDER - 45N21
WASHER - 31W17
(2) SCREW - 1/4" - 28 x 1"
61300098
3/4" Ø
MOUNTING STUD
SCALE - 45N88
(2) SCREW - No. 6-32 X 1/4"
PINION - 31W15
ROLL PIN - 1/8" x 7/8"
Fig. 4-Torch Holder Assembly - P/N 16V83
(Supplied with PT-20AM Torch Assembly, P/N 21371)
REVISION DATA
Revision B - Added a rubber boot P/N49N83 to the power cable. Reference to new P/N's 22057, 21977,21785 and
21786 were added.
Revision C - Shield shoud P/N 21533 was replaced by P/N 22330 and handle P/N 948177 was replaced by P/N 22329
on P/N's 21785 and 21786.
Revision D - The torch body was modified to no longer need the electrode seat P/N 21372. The cutting parameter
charts were updated to include stainless and aluminum.
Revision E - Added 50Hz Electrode P/N 0558001617 to Spareparts list and Parts diagram. Added Note to page 2
explaining differences of the torch body insulator revisions.
7
ESAB Welding & Cutting Products, Florence, SC Welding Equipment
COMMUNICATIONS GUIDE - CUSTOMER SERVICES
A. CUSTOMER SERVICE QUESTIONS:
Order Entry Product Availability Pricing Shipping Information
Order Changes Saleable Goods Returns Delivery
Telephone: (800)362-7080 / Fax: (800)634-7548
Telephone: (800)783-5360 / Fax: (800)783-5362
Telephone: (800)235-4012 / Fax: (888)586-4670
B. ENGINEERING SERVICE: Telephone: (843) 664-4416 / Fax : (800) 446-5693
Welding Equipment Troubleshooting Hours: 7:30 AM to 5:00 PM EST
Warranty Returns Authorized Repair Stations
C. TECHNICAL SERVICE: Telephone: (800) ESAB-123/ Fax: (843) 664-4452
Part Numbers Technical Applications Hours: 8:00 AM to 5:00 PM EST
Performance Features Technical Specifications Equipment Recommendations
D. LITERATURE REQUESTS: Telephone: (843) 664-5562 / Fax: (843) 664-5548
E. WELDING EQUIPMENT REPAIRS: Telephone: (843) 664-4487 / Fax: (843) 664-5557
Repair Estimates Repair Status Hours: 7:30 AM to 3:30 PM EST
F. WELDING EQUIPMENT TRAINING:
Telephone: (843)664-4428 / Fax: (843) 679-5864
Training School Information and Registrations Hours: 7:30 AM to 4:00 PM EST
G. WELDING PROCESS ASSISTANCE:
Telephone: (800)ESAB-123 / Fax: (843) 664-4454 Hours: 7:30 AM to 4:00 PM EST
H. TECHNICAL ASST. CONSUMABLES:
Telephone: (800) 933-7070 Hours: 7:30 AM to 5:00 PM EST
Eastern Distribution Center
Central Distribution Center
Western Distribution Center
Hours: 7:30 AM to 4:00 PM EST
Telephone: (800) ESAB-123/ Fax: (843) 664-4452/Web: http://www.esab.com
F-15-114-e 10/2000 Printed in U.S.A.
IF YOU DO NOT KNOW WHOM TO CALL
Hours: 7:30 AM to 5:00 PM EST
8
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