Flashbacks - Agilent Technologies 240 Series AA User Manual

Safety Practices and Hazards
When solvent extractions of perchloric solutions are performed, some of the acid
NOTE
may dissolve in the organic solvent that is subsequently aspirated. Also, if the
organic solution is aspirated while floating on the surface of the acid, do not allow
the capillary tube to drop below the organic layer and suck up aqueous perchloric
acid.
When using perchloric acid, wear approved ear protectors and approved safety
glasses and ensure that all instrument safety covers are in position.

Flashbacks

A flashback is an explosion of the gas mixture in the spray chamber, which can
occur for several reasons. For more details, refer to the SpectrAA software Help.
Agilent AA spectrometers have several safety features in place to prevent
flashbacks, and flashbacks are very rare in circumstances where instruments are
properly maintained.
In the rare event that a flashback does occur, the Agilent AA instrument safety
features are designed to safely relieve the pressure and minimize damage. In
addition to reading the list below, refer to the Maintenance section of this User's
Guide and the SpectrAA software Help for recommended maintenance procedures
to prevent flashbacks.
Analysis over many years has shown that in most cases, flashbacks are
associated with one or more of the following points. If you experience a flashback,
check this list to see if any of the points are relevant, and take steps to remedy the
situation.
1 Keep the burner clean. Deposits must not be allowed to build up in or on the
burner slot because they can partially block it. Blockages can cause the
pressure to build up in the spray chamber and breach the seal provided by the
liquid trap. Alternatively, glowing particles can fall down through the slot into
the spray chamber and ignite the combustible gas mixture inside.
Be especially careful of very small deposits in the ends of the burner slot
because they disrupt the laminar gas flow and allow the flame to burn back
into the spraychamber at "Flame Off" when the gas flow is reduced.
The use of a hard object to brush off glowing carbon particles during flame
operation is not recommended because of the increased risk of knocking one
of the particles down the slot.
22 Agilent 240/280 Series AA (including Zeeman)