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Under these circumstances, use a leak detection spray or liquid to identify, then rectify the
leak before using the Pistol. If there is no movement of pressure gauges, then there is no
identifiable leak and the pistol is safe to use.
NB: Leak Test Information is based on the assumption that all pressure gauges are in
good working order, with any visible defects having already been rectified e.g.
damaged hoses, broken flowmeters etc…
1.1.3 Flashback
Poorly maintained equipment may on occasion produce flashbacks If hose protection and
flashback arrestors are fitted, the risk of flames reaching the fuel gas and oxygen supplies is
virtually eliminated.
However, flashback, particularly if sustained, can seriously damage the nozzle assembly.
Therefore, if flashback occurs, the following procedure should always be carried out:
1) Immediately close the Pistol valve.
2) Shut off the Oxygen Supply Valve.
3) Shut off the Fuel Gas Supply Valve.
4) If fitted, operate the Safety Shut-Off Handle on the flowmeter.
5) Re-open the Pistol Valve and allow air to flush the nozzle parts for approximately 30
seconds.
6) Restart the system as identified in Section 3.2
7) If on re-lighting the flashback is repeated, shut off as above and ascertain the cause.
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