EUTECH INSTRUMENTS TURBIDIMETER TN-100 WATERPROOF PORTABLE METER Instrukcja Obsługi Pobierz pdf (Strona 24)

Instruction Manual TN-100/ T-100

Figure 14 shows the waterproof TN-100/ T-100 turbidimeter basic optical

system. It includes a light source and a detector to monitor the light

scattered at 90° with respect to the incident beam.

90°

Lens

Glass Sample Vial

Transmitted

Light

Scattered Light

Lamp

Figure 14: Basic Nephelometric arrangement for turbidity measurements

8.4

Nephelometric Turbidity Units (NTU)

Nephelometric Turbidity Units (NTU): Unit of measure used when relating

the light scattered by a liquid media to the light scattered by a known

concentration of a standard solution. This unit of measure is recognized as

a measure of the optical clarity of an aqueous sample. NTU is the

accepted unit of measurement for turbidity.

Another unit commonly used to measure turbidity is Formazin Turbidity

Unit (FTU). The two units of measure of turbidity are equivalent: 1 NTU = 1

FTU.

8.5

Indexing a Vial

The United States Environmental Protection Agency (US EPA)

recommends that vials used for turbidimeter calibration or sample

measurement be indexed.

To index a sample vial, slowly rotate the vial throughout one complete

revolution (360°). While rotating the sample vial, observe the display and

locate the position that the vial is in which provides the lowest turbidity

reading. This position is the indexed position of the vial.

Mark this position on the vial (not on the cap) against the mark on the

meter.

After indexing a vial, make sure the vial will always be placed inside the

sample well in the indexed position.

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