Page 67 - The City and Guilds Textbook: Plumbing Book 1 for the Level 3 Apprenticeship (9189), Level 2 Technical Certificate (8202) and Level 2 Diploma (6035)

Chapter 1 Health and safety practices and systems

● Inspect the torch. Check that the inlet connection is in good condition for a
tight connection. Check for obvious physical damage to the torch.
● Make sure the acetylene regulator is turned off by turning the regulator
handle anti-clockwise out a few turns, then turn on the gas valve on top of
the cylinder. Only turn the control valve half a turn. This allows the bottle to
be turned off quickly in an emergency. Never allow acetylene gas pressure
to exceed 15 PSI. At higher pressures acetylene becomes unstable and may
ignite spontaneously or explode.
1 After turning on the acetylene cylinder control valve, open the regulator
valve by turning the handle clockwise. This should be done very slowly,
while watching the low pressure gauge. Open only until the pressure
indicated is between 5 and 8 PSI.
2 Open the gas valve on the blow pipe handle until you hear gas escaping.
This is to purge the air from the acetylene hose. Then observe the low
pressure gauge to see if the pressure remains steady during flow, to
ensure you have the regulator set correctly.
3 Close the acetylene valve on the torch.
4 Check for leaks by using suitable non-greasy leak detection fluid.
● Turn the oxygen regulator pressure off by turning the regulator handle a few
turns anti-clockwise then proceed with the following steps to adjust the
oxygen pressure.
1 Open the oxygen cylinder control valve all the way.
2 Open the regulator valve slowly, watching the low pressure gauge as you
do so, until the pressure reads between 25 and 40 PSI.
3 Open the oxygen valve on the blow pipe to allow the air to vent out of
the hose until the hose is purged, about three to five seconds for an 8 m
hose.
4 Close the blow pipe valve.
5 Check for leaks by using suitable non-greasy leak detection fluid.
● Make sure that you purge both acetylene and oxygen lines (hoses) prior to
igniting the torch. Failure to do this can cause serious injury to personnel and
damage to the equipment.

Safe lighting and extinguishing procedures for
oxyacetylene equipment

To light
1 Open the acetylene blow pipe valve a quarter turn and light the acetylene KEY POINT
with a friction-type lighter.
2 NEVER LIGHT THE OXYACETYLENE TORCH WITH MIXED GAS. Make sure that you purge
both acetylene and
3 Adjust the acetylene flame to the desired velocity. oxygen lines (hoses) prior
4 For welding mild steel, open the oxygen blow pipe valve and adjust to neutral to igniting the torch.
flame (equal amounts of acetylene and oxygen). Failure to do this can
5 For brazing or bronze welding, open the oxygen blow pipe valve and adjust to cause serious injury to
a slightly oxidising flame (slightly more oxygen than acetylene). personnel and damage to
the equipment.

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