Hanna Instruments hi 93741 User Manual
4
The quantity of radiation absorbed is given by the Lambert-Beer
Law:
Law:
log
I
o
/
I
=
ε
λ
c d
Where
log
I
o
/
I
= Absorbance (A)
ε
λ
= molar extinction coefficient of the substance at
wavelength
λ
c = molar concentration of the substance
d = optical distance light travels through sample
d = optical distance light travels through sample
Therefore, the concentration "c" can be calculated from the color
intensity of the substance determined by the emitted radiation
intensity of the substance determined by the emitted radiation
I
, as
the other factors are known.
BLOCK DIAGRAM OF A COLORIMETER
A monochromatic LED (Light Emitting Diode) emits radiation at a
single wavelength, supplying the system with the intensity
single wavelength, supplying the system with the intensity
I
o
.
Since a substance absorbs the color complimentary to the one it emits
(for example, a substance appears yellow because it absorbs blue
light), Hanna colorimeters use LEDs that emit the appropriate
wavelength to measure the sample.
The optical distance (d) is measured by the diameter of the cuvet
containing the sample.
The photoelectric cell collects the radiation
(for example, a substance appears yellow because it absorbs blue
light), Hanna colorimeters use LEDs that emit the appropriate
wavelength to measure the sample.
The optical distance (d) is measured by the diameter of the cuvet
containing the sample.
The photoelectric cell collects the radiation
I
that is not absorbed by
the sample and converts it into an electric current, producing a
potential in the mV range.
The microprocessor uses this potential to convert the incoming value
into the desired measuring unit and to display it on the LCD.
The measurement process is done in two phases: setting the meter to
zero and the actual measurement.
The cuvet has a very important role because it is an optical element,
and thus requires particular attention.
It is important that both the measurement and the calibration
(zeroing) cuvets are optically identical to provide the same measure-
ment conditions. Whenever possible use the same cuvet for both.
It is also necessary that the cuvet's surface is clean and not scratched,
in order to avoid measurement interference due to unwanted reflec-
tion and absorption of light.
potential in the mV range.
The microprocessor uses this potential to convert the incoming value
into the desired measuring unit and to display it on the LCD.
The measurement process is done in two phases: setting the meter to
zero and the actual measurement.
The cuvet has a very important role because it is an optical element,
and thus requires particular attention.
It is important that both the measurement and the calibration
(zeroing) cuvets are optically identical to provide the same measure-
ment conditions. Whenever possible use the same cuvet for both.
It is also necessary that the cuvet's surface is clean and not scratched,
in order to avoid measurement interference due to unwanted reflec-
tion and absorption of light.
LED
EMITTED LIGHT
CUVET
MICROPROCESSOR
LIGHT
DETECTOR
49
WARRANTY
WARRANTY
WARRANTY
WARRANTY
WARRANTY
Hanna Instruments reserves the right to modify the design,
construction and appearance of its products without advance notice.
construction and appearance of its products without advance notice.
All Hanna Instruments meters are warranted for two years
against defects in workmanship and materials when used for their
intended purpose and maintained according to instructions.
This warranty is limited to repair or replacement free of charge.
Damages due to accidents, misuse, tampering or lack of prescribed
maintenance are not covered.
If service is required, contact the dealer from whom you purchased the
instrument. If under warranty, report the model number, date of
purchase, serial number and the nature of the failure. If the repair
is not covered by the warranty, you will be notified of the charges
incurred.
If the instrument is to be returned to Hanna Instruments, first obtain
a Returned Goods Authorization Number from the Customer Service
department and then send it with shipment costs prepaid. When
shipping any instrument, make sure it is properly packaged for
complete protection.
To validate your warranty, fill out and return the enclosed warranty
card within 14 days from the date of purchase.
All rights are reserved. Reproduction in whole or in part is
prohibited without the written consent of the copyright owner,
Hanna Instruments Inc., Woonsocket, Rhode Island, 02895 , USA.
against defects in workmanship and materials when used for their
intended purpose and maintained according to instructions.
This warranty is limited to repair or replacement free of charge.
Damages due to accidents, misuse, tampering or lack of prescribed
maintenance are not covered.
If service is required, contact the dealer from whom you purchased the
instrument. If under warranty, report the model number, date of
purchase, serial number and the nature of the failure. If the repair
is not covered by the warranty, you will be notified of the charges
incurred.
If the instrument is to be returned to Hanna Instruments, first obtain
a Returned Goods Authorization Number from the Customer Service
department and then send it with shipment costs prepaid. When
shipping any instrument, make sure it is properly packaged for
complete protection.
To validate your warranty, fill out and return the enclosed warranty
card within 14 days from the date of purchase.
All rights are reserved. Reproduction in whole or in part is
prohibited without the written consent of the copyright owner,
Hanna Instruments Inc., Woonsocket, Rhode Island, 02895 , USA.