Thermo Scientific Lab-Line Imperial 3 Operation And Repair Manual And Parts List page 16

MAINTENANCE:
CARE AND CLEANING OF STAINLESS STEEL:
CAUTION: DISCONNECT UNIT FROM POWER SOURCE PRIOR TO CLEANING.
WE RECOMMEND QUALIFIED SERVICE PERSONNEL MUST PERFORM ALL
SERVICE.
WARNING: ELECTROLYSIS CAN DAMAGE STAINLESS STEEL.
OCCURS WHEN AN OBJECT IS ALLOWED TO REST DIRECTLY ON THE
SURFACE OF STAINLESS STEEL, TRAPPING MOISTURE THAT BECOMES
OXYGEN-STARVED,
OXYGEN.
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 for, 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
maintaining neutral pH and conducting frequent cleanings with detergent and water can
obtain years of trouble-free service from stainless steel products.
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 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.
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