Hanna-instruments HI 4321 Manual do Utilizador descarregar pdf (Página 43)

DIRECT/USP MEASUREMENT

In this measure mode the user can check for ultra pure water using the United States Pharmacopeia standard

(USP <645>).

This USP standard consists of three stages (one in-line and two off-line tests) as following:

Stage 1 - this is an in-line test.

Test steps:

• Measure the temperature of the water and the uncompensating conductivity readings. The measurement

may be performed in a suitable container or as in-line measurement.

• The temperature will be round down to the nearest 5 °C and look up the corresponding conductivity value

in the below table.

• If the measured conductivity is lower than the conductivity in the table, then the water meets the USP

requirements.

• Otherwise, proceed to Stage 2 testing.

Stage 2 - this is an off-line test.

Test steps:

• Store the water sample in an enclosed clean container that has been rinsed previously with water of the

same quality.

• Adjust the sample’s temperature to 25 °C and agitate the sample to ensure that it has equilibrated with

ambient CO

• If the measured conductivity is less than 2.1 µS/cm, then the sample has met the USP requirements.

• Otherwise, proceed to Stage 3 testing.

erutarepmeT

)C°(

ytivitcudnoC

)mc/Sµ(

erutarepmeT

)C°(

ytivitcudnoC

)mc/Sµ(

06.0551.2

58.0062.2

019.0564.2

510.1075.2

021.1577.2

523.1087.2

034.1587.2

535.1097.2

047.1599.2

548.10011.3

059.1

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Hanna-instruments HI 4321 Manual do Utilizador Página 43