Hanna Instruments HI 98713 Instruction Manual page 13

CUVET OILING
To hide minor imperfections and scratches, the cuvets should be oiled outside with the supplied
silicone oil. This is very important, especially for low turbidity samples (< 1 FTU), otherwise
scratches can contribute and alter turbidity readings.
The silicone oil has the same refractive index as the glass and will not alter the turbidity readings.
It is important to apply only a thin layer of silicone oil.
Warning: Do not apply the oil in excess, it may retain dirt or contaminate the cuvet holder of the
instrument, altering the turbidity readings.
It is very important to apply the silicone oil on a clean, dry cuvet. Apply a few drops of oil and wipe
the cuvet thoroughly with a lint-free cloth. Wipe off the excess of oil till you obtain a thin, uniform
layer. If the procedure is correctly followed, the cuvet should appear nearly dry with no visible oil.
Note: The supplied cloth for oiling should be stored together with the silicone oil bottle and cuvets,
taking care to avoid contamination with dirt. After a few oiling procedures the cloth will
contain enough oil to wipe the bottle with it without adding more oil. From time to time add
some drops of oil on the cuvet to provide the necessary oil quantity in the cloth.
INDEXING A CUVET
It is very important for low turbidity readings to always insert the cuvet into the instrument in the
same position.
All cuvets are factory indexed. This index can be used to put the cuvet with the factory mark on the
cuvet aligned with the sign on the instrument top.
To further reduce the effect of glass imperfections, the cuvet can be indexed and use this new index
as the position mark.
For indexing one cuvet or matching multiple cuvets the continuous reading mode is suggested. In this
mode if READ is kept pressed, multiple successive readings are taken without turning off the LED.
After first reading is displayed, it is possible to open the cuvet lid and rotate the cuvet without
generating an error condition. The turbidity is immediately displayed, reducing drastically the
measurement time. The LED of the instrument will turn off only when READ
Note: The instrument can not perform continuous readings if the average mode is on.
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