Lighting And Using The Cutting Torch - Hobart 770 500 Owner's Manual

7-3. Lighting And Using The Cutting Torch

1
Always purge gas from the system
!
before lighting torch to prevent a
possible mixed-gas
Purge gas in a well ventilated area
and away from flame or sparks. See
Sections 7-1 and 7-2.
Do not use matches or a cigarette
!
lighter to ignite the gas.
.
See Sections 5-4 and 5-3 for oxygen
and fuel pressure recommendations.
.
See Sections 7-1 and 7-2 for informa-
tion on adjusting oxygen and fuel pres-
sure.
1 Spark Lighter
2 Oxygen Valve
3 Preheat Oxygen Valve
4 Fuel Valve
5 Cutting Lever
Lighting The Torch
Hold the spark lighter near the torch tip.
Slowly open the fuel valve on the torch
handle 1/4 turn and quickly squeeze the
spark lighter to light the flame.
Slowly open the oxygen valve on the torch
to the desired pressure.
3 5
Continue to open the fuel valve until the
black sooty smoke disappears and the
explosion. flame begins to move away from the tip.
Failure to force a sufficient amount
!
of fuel gas through the tip will cause
the tip to overheat and may cause a
flashback or backfire.
Slowly open the preheat oxygen valve on
the cutting attachment; a white-hot feather
(flame) appears.
Slowly add oxygen until the feather begins
to disappear into the bright cone at the end
of the tip. This produces a neutral flame
(ratio of fuel to oxygen is 1:1).
Using The Cutting Torch
Hold the torch tip about 1/4 in. (6 mm) from
the metal to be cut.
Heat the metal until it is bright red (about
1550° F or 843° C).
Slowly depress the cutting lever on the
cutting attachment. Let the oxygen stream
burn through the metal, then completely
depress the lever to begin the cutting
process.
2
4
Neutral Flame
Even mixture of fuel and oxygen
Tools Needed:
161-037 / 038
When Finished Cutting
NOTICE − Shut down the torch in the cor-
rect sequence or the torch may be dam-
aged. Oxygen must be released from the
system first or residual fuel in the handle or
fuel hose may burn. Fuel cannot burn
without oxygen.
When finished cutting, release the cutting
lever. Close the oxygen preheat valve on
the torch handle first and then close the fuel
valve on the torch handle.
Turn valves at fuel and oxygen cylinders
clockwise to the closed position.
Open the fuel valve on the torch handle to
relieve pressure; both gauges on the fuel
regulator should indicate zero (0) pressure.
Close the fuel valve on the torch handle.
Turn fuel regulator adjustment handle coun-
terclockwise until there is no pressure on
the regulator diaphragm.
Open the preheat oxygen valve on the torch
handle to relieve pressure; both gauges on
the oxygen regulator should indicate zero
(0) pressure. Close the preheat oxygen
valve and oxygen valve on the torch
handle.
Turn oxygen regulator adjustment handle
counterclockwise until there is no pressure
on the regulator diaphragm.
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