Thermo Scientific 11174729, Instruction Manual

Page: 38 / 66

Chapter 6
HAZARDS, PRECAUTIONS AND LIMITATIONS OF USE
6-2 MR23i Thermo Fisher Scientific
Chemical Corrosion
This corrosion is characterised by chemical reactions due to the
existence of an electrolyte liquid on the surface of the item. If these
substances are allowed to remain on the surface the corrosion will
almost certainly occur. This produces first a discoloration of the
anodisation then pitting of the metal. Aluminium is a metal which
easily reacts with ionic solutions. Anodisation produces a protec-
tive layer on the surface of the rotor.
Acidic and alkaline solutions sustaining their pH level will create
problems of corrosion in aluminium rotors. Chlorides, present in
salts or even in skin contact with the rotor are among the most
aggressive and harmful substances commonly found in the labora-
tory.
The chemical products which are the origin of this corrosion do not
necessarily originate from broken tubes - for example they could
come from:
• Chemical vapours present in the laboratory which are dissolved
in the residual humidity, in condensed water (refrigerated cen-
trifuges) present at the base of the rotor pockets.
• Corrosive liquids originating from overfilled uncapped tubes
(the liquid overflowing during centrifugation)
• Inserts, adaptors, racks, bottles whose exterior has been soiled
by a chemical product or poorly rinsed after decontamination
(with bleach, for example).
Note If the products are very corrosive, simply rinsing is insufficient. Resi-
dual traces dissolve little by little in the humidity present in the bot-
tom of the pocket, in the condensed water (such as occurs when
putting an ambient temperature insert in a cold rotor).
BEWARE of the presence of solid particles beneath tubes, inserts,
racks or adaptors. These particles are crushed by the centrifugal
force and penetrate the protective, anodised layer of buckets and
rotors, thus creating easy pathways for corrosion.