EUTECH INSTRUMENTS TURBIDIMETER TN-100 WATERPROOF PORTABLE METER Instrukcja Obsługi Pobierz pdf (Strona 27)

Instruction Manual TN-100/ T-100

9.6 Calibration

1. Do not open the vials with calibration standards.

2. Check that the standards have not expired.

3. Make sure the calibration vials are free of dust, smudges and

scratches before use.

4. Conduct the calibration in the same manner each time. Variations in

how calibration is performed could yield inaccurate measurements.

5. It is very important that the user(s) who perform calibration have been

trained to do so. Creating a Standard Operating Procedure (SOP) for

the user(s) to read, learn, and practice may help to ensure accuracy.

9.7

Dilution

This dilution procedure is necessary only when your turbidity

measurement is above 1000 NTU.

1. To measure the turbidity above 1000 NTU, dilute the sample with

turbidity-free water.

2. Turbidity-free water can be obtained by filtering deionized water

through a < 0.2µm filter membrane with precision-sized pores.

3. Measure the volume of the sample before dilution and record the value

in ml (Vs).

4. Take a known volume (Vd) of dilution water and add it to the sample.

5. Pour 10 ml of the diluted sample in a clean vial and measure the

turbidity of the diluted sample. Record this value in NTU (Td).

6. Calculate the true turbidity (T) of the original sample - in NTU - using

the following formula:

T = Td * (Vs + Vd) / Vs

Example:

 Dilute 20 ml of the original sample (whose turbidity is above

1000NTU) with 50 ml of dilution water.

 Measure the turbidity of the diluted sample.

 If the reading is 300 NTU, the turbidity of the original sample

is 1050 NTU. (In this case: Td=300NTU, Vs=20ml, Vd=50ml,

so T = 300 * (20+50) / 20 = 300*70/20 = 21000/20 = 1050)

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EUTECH INSTRUMENTS TURBIDIMETER TN-100 WATERPROOF PORTABLE METER Instrukcja Obsługi Strona 27