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MAINTENANCE:
(Con’t)
THE ALLOY CALLED STAINLESS:
Stainless steel is an alloy of steel with chromium and nickel that
increase the metal’s resistance to rust and corrosion. Yet, if not properly cared ,
stainless steel can rust and corrode.
Exposure to air provides the passivation, or oxide layer coating, for clean
stainless by producing a thin, durable chromium-oxide film that forms rapidly
on the alloy surface to give stainless its characteristic “stainless” quality. Also
exposure of the surface to other oxidizing environments can produce a
passivating film or coating.
However, if free oxygen is not available due to scale or contamination
buildup the metal surface may become vulnerable to rusting and corrosion as
well as pitting. But by maintaining neutral pH and conducting frequent cleanings
with detergent and water, years of trouble-free service from stainless steel
products can be obtained.
SOME STAINLESS GUIDELINES TO CONSIDER:
Distilled water is recommended. Please note, if this water is very pure it
may be corrosive to stainless. When filling a bath or incubator, ALWAYS ADD 2
to 40 PPM (20 TO 40 MG/LITER) DISODIUM PHOSPHATE OR SODIUM
BICARBONATE, ADJUSTING DOSAGE TO PROVIDE A pH VALUE OF 7 TO 9.
If not available, use clean, aerated soft tap water provided the total solids
concentration is
<
500 PPM.
WE DO NOT RECOMMEND USING 18 MEG OHM DEIONIZED WATER.
If
this is the only source of treated water available—mix with regular tap water
at a
50/50 ratio.
THE pH FACTOR:
Check pH regularly. If pH is
<
6.0, add disodium phosphate to increase pH
to a 7 to 9 value. Sodium carbonate or sodium bicarbonate may be used but
they tend to form scale that must be rinsed out regularly. If pH is
>
10.0, add
sodium bisulfate to decrease pH to a 7 to 9 value. Avoid adding harsh alkalines
or acids since these may cause localized corrosion and result in unstable pH.
SPECIAL STAINLESS CONSIDERATIONS:
WARNING:
IF IT IS NECESSARY TO USE THE FOLLOWING CHEMICALS,
LIMIT EXPOSURE TIME TO A MAXIMUM OF 3 HOURS—ALWAYS CLEAN
SURFACES IMMEDIATELY AFTER USE.
Chemicals which should be limited to a 3-hour maximum exposure time to
stainless steel are:
Aluminum chloride
E.D.T.A.
Potassium permanganate
Barium chloride
Ferrous chloride
Potassium thiocyanate
Calcium chloride
Lysol
Sodium hypochlorite
Chlorinated Lime
Mercury salts
Stannous chloride
Citric acid (boiling)
Phenol
Tartaric acid
Dakin’s solution
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