Hanna-instruments HI 93703 Bedienungsanleitung PDF herunterladen (Seite 5)

5

IR LED

EMITTED LIGHT (890 nm)

CUVET

LIGHT

DETECTOR

90° SCATTERED

LIGHT

PRINCIPLE OF OPERATION

* 1 FTU = 1 NTU

HI 93703-11 has been designed to perform

measurements according to the ISO 7027 In-

ternational Standard.

The instrument functions by passing a beam of

infrared light through a vial containing the sample

being measured.

A sensor, positioned at 90° with respect to the

direction of light, detects the amount of light

scattered by the undissolved particles present

in the sample. The microprocessor converts

such readings into FTU* values.

As noted above, FTU unit is equal to the NTU

unit. However, there are other known measure-

ment units for turbidity: Jackson Turbidity Unit

(JTU) based on the old method of Jackson's

candle, and Silica Unit (mg /L of SiO

2

). For your

reference the conversion table between these

measurement units is shown below:

JTU FTU/NTU SiO

2

(mg/L)

JTU 1 19 2.5

FTU/NTU 0.053 1 0.13

SiO

2

(mg/L) 0.4 7.5 1

20

BATTERY REPLACEMENT

All components have been selected to mini-

mize current drain without compromising func-

tionality. In order to minimize the battery con-

sumption, the meter is equipped with an auto-

shut off function which switches the meter off

after 5 minutes of non-use.

The four 1.5V batteries guarantee 60 hours of

working life (or 900 measurements).

In order to obtain accurate measurements, the

battery level is monitored every time the meter

is switched on.

In addition, a "LO BAT" indication will appear on

the lower right corner of the display when the

batteries are weak (<10%). All four batteries

need to be replaced.

When the batteries are too weak to ensure

reliable measurements, the message 0% LO

BAT appears for a few seconds, and then the

meter will automatically switch itself off. Re-

place the batteries immediately.

LOBAT

0

%

LO BAT

1 2 3 4 5 6 7 8 9 10 11 12

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