Hanna Instruments LP 2000 - Manual (Page 3)

5 4
i) Socket for 12 Vdc power adapter
FUNCTIONAL DESCRIPTION
* 1 FTU = 1 NTU
Hanna Instruments uses the primary standard AMCO-AEPA-1 to
avoid all formazine-related problems. Formazine is a toxic, unstable
substance, which requires particular care. Calibration requiring formazine
standards must be preformed immediately after preparation of the
standards. Formazine standards may not be reused because of their
short life. LP 2000 standards are extremely stable and have a shelf
life of up to six months. Uncontaminated standards may be reused.
LP 2000 can be used with both AMCO-AEPA and formazine stan-
dards.
FTU is equal to the NTU. However, other known measurements
include: Jackson Turbidity Unit or JTU (based on the old method of
Jackson's candle), and Silica Unit in mg/L of SiO
2
. See the conversion
table below for these units:
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
MEASURE UNITS
LP 2000 has been designed to perform measurements according to
the ISO 7027 International Standards.
The instrument functions by passing a beam of infrared light through
a vial containing the sample being measured.
The light source is a High Emission Infrared LED with a wavelength
peaking at 890 nm, which reduces interference caused by colored
samples to a minimum.
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.
IR LED
EMITTED LIGHT (890 nm)
CUVET
LIGHT
DETECTOR
90° SCATTERED
LIGHT
PRINCIPLE OF OPERATION
1) Cuvette holder
2) Dual level LCD (Liquid Crystal Display)
3) ON/OFF key, to switch the meter ON and OFF
4) CAL key, to enter calibration mode
5) READ/
▲, to perform measurements, and set the day and
month of the last calibration
6) DATE/ , to display the last calibration date, and select the
month or day of the last calibration
▲