Tweco Thermal Arc TA 500 - Manual (Page 37)

Manual No 0-0470 4-3 Service
5. Install the new tip (6) in the inner tip retainer.
This is installed by pressing it in from the back.
If the O-rings are properly lubricated, thumb
pressure is adequate (with a slight twisting
motion of the thumb).
6. Install the inner tip retainer with the tip in place
on the front end of the torch. The tip retainer
must be screwed completely into place. It is
essential that the ceramic O-ring on the tip be
firmly in contact with the electrode.
7. Install the outer insulator (13) on the torch.
Before pushing this into place, make sure that
the O-rings on the inside diameter are in good
condition and properly lubricated. The insula-
tor must be pushed onto the torch as far as it
will go.
8. Install the coolant baffle (20) on the front of the
inner tip retainer. The triangular projections go
into the holes in the inner tip retainer that are
aligned with the marks on the plastic torch body.
If the holes do not align exactly, use the closest
ones. DO NOT loosen the inner tip retainer to
improve the alignment.
9. Install the end piece (16) in the front of the end
cap, small end forward.
10. Install O-ring (15) in the end cap against the
back of the ceramic end piece. A light coating
of O-ring lubricant will help hold this O-ring in
place until the end cap is installed.
11. Press the end cap (17), complete with end piece
(16) and O-ring (15) in place, onto the outer in-
sulator (13). Install the collar (19) over the end
cap (17) and screw it onto the torch body.
This completes the torch assembly. There is a chance
that water may get in the plasma gas passages in the
torch during assembly. All water must be removed
before operation.
To remove all traces of water:
1. Turn the Console RUN/SET switch to SET.
2. Turn on the coolant.
3. Turn on the plasma gas (nitrogen). Do not turn
on the shield water (water shield cutting). The
shield gas may be on or off (dual flow cutting).
4. With plasma gas flowing, look for traces of
moisture in the gas stream.
WARNING
Do not operate the torch unless the plasma gas
stream is completely free of moisture.
Be sure to turn on the secondary gas or shield water
before starting to cut.
4.2 TAC 500 Power Supply
Maintenance
The only routine maintenance the TAC 500 Power Sup-
ply requires is an occasional removal of the cover and
side panel and a thorough blowing out of dust with an
air hose.
4.3 HE 200 Coolant Recirculator
Maintenance
Parts in the HE 200 Coolant Recirculator require rou-
tine maintenance. The coolant level should be checked
daily and Thermal Arc coolant added to keep the level
at the crosswires in the cylindrical section. If Thermal
Arc coolant is not available, distilled or deionized wa-
ter may be used if the temperature does not go below
freezing. The resistivity of the water must measure
above .1 megohm cm.
CAUTION
Do not use tap water. It could cause severe dam-
age to the torch.
The reservoir contains a cap/cartridge assembly which
includes a small cartridge of deionizing resin to main-
tain the resistivity of the coolant. The cartridge must
be replaced when it changes from gray to straw color.
A coolant filter with a reusable screen is located above
the pump. The screen should be removed and cleaned
once every six months or at any time the coolant pres-
sure drops. To remove the filter screen, remove the
top of the HE 200 unit and unscrew the hex nut on the
bottom of the filter housing.
The coolant recirculator has a pressure relief valve that
is factory set at 150 psi (10.3 bar) and should not require
adjustment. Normal operating pressure is approxi-
mately 110 psi (7.6 bar). If the pressure relief valve must
be adjusted see the HE-200 manual.