Hanna Instruments GroLine HI98168 User manual

INSTRUCTION MANUAL
HI98168
Professional Soil pH Meter

Thank you for choosing a Hanna Instruments product.
Please read this instruction manual carefully before using the instrument.
This manual will provide you with the necessary information for correct use of the
instrument, as well as a precise idea of its versatility.
If you need additional technical information, do not hesitate to e‑mail us at
[email protected] or view our worldwide contact list at www.hannainst.com.
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.
Dear
Customer,

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PRELIMINARY EXAMINATION ..............................................................................................
SAFETY MEASURES ............................................................................................................
GENERAL DESCRIPTION ......................................................................................................
FUNCTIONAL DESCRIPTION ................................................................................................
SPECIFICATIONS ................................................................................................................
SOIL pH ............................................................................................................................
ORGANIC SUBSTRATE ........................................................................................................
IRRIGATION WATER ...........................................................................................................
NUTRIENT SOLUTION .........................................................................................................
OPERATIONAL GUIDE .........................................................................................................
pH CALIBRATION ...............................................................................................................
pH BUFFER TEMPERATURE DEPENDENCE ............................................................................
GOOD LABORATORY PRACTICE (GLP) ...................................................................................
SETUP ..............................................................................................................................
LOGGING ..........................................................................................................................
AUTOEND .........................................................................................................................
TEMPERATURE CALIBRATION (FOR TECHNICAL PERSONNEL ONLY) .........................................
PC INTERFACE ...................................................................................................................
BATTERIES REPLACEMENT ..................................................................................................
TEMPERATURE CORRELATION FOR pH SENSITIVE GLASS .......................................................
ELECTRODE CONDITIONING AND MAINTENANCE ..................................................................
TROUBLESHOOTING GUIDE ................................................................................................
ACCESSORIES ...................................................................................................................
TABLE OF CONTENTS
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Remove the instrument from the packing material and examine it carefully to make sure that no
damage has occurred during shipping. If there is any damage, please contact your local Hanna
Instruments Office.
Each instrument is supplied with:
•HI12923 Glass body, conical tip, refillable pH electrode with internal temperature sensor
•HI700663 Cleaning solution for soil deposits (1 pc.)
•HI700664 Cleaning solution for humus deposits (1 pc.)
•HI7051M Soil Test Solution (230 mL)
•HI920015 USB cable
•HI721319 ground auger
•pH 4.01 & 7.01 Buffer solutions (230 mL each)
•100 mL Beaker (2 pcs.)
•1.5V AA Batteries (4 pcs.)
•HI720161 Hard carrying case
•Instruction Manual and Quick Reference Guide
•Instrument Quality Certificate
PRELIMINARY EXAMINATION
Note: Save all packing material until you are sure that the instrument functions correctly. All
defective items must be returned in the original packing with the supplied accessories.
SAFETY MEASURES
Before using this product, make sure that it is entirely suitable for your specific application and for
the environment in which it is used.
Operation of this instrument may cause interference to other electronic equipment, requiring the
operator to take steps to correct interference. Any variation introduced by the user to the supplied
equipment may degrade the instrument’s EMC performance.
To avoid damages or burns, do not put the instrument in microwave ovens. For your and the
instrument’s safety, do not use or store the instrument in hazardous environments.

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GENERAL DESCRIPTION
Other features include:
• Log on demand up to 200 samples (100 pH and 100 mV).
• Auto Hold feature, to freeze first stable reading on the LCD.
• GLP feature, to view last calibration data for pH.
• PC interface.
HI98168 is a portable, pH and temperature meter specifically designed for direct soil measurement.
It is provided with a series of new diagnostic features which add an entirely new dimension to the
measurement of pH, by allowing the user to dramatically improve the reliability of the measurement:
• Seven standard buffers (pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01 and 12.45) for calibration.
• pH calibration up to five calibration points (see instrument specifications).
• Custom calibration with up to five custom buffers.
• Messages on the graphic LCD for an easy and accurate calibration.
• Cal Check™ Diagnostic features to alert the user when the electrode needs cleaning.
• Optional user enabled “Outside Calibration Range” warning.
• Monitoring of the electrode aging.
• User selectable “Calibration Time Out” to remind when a new calibration is necessary.
This meter is supplied with a pH electrode specifically designed for direct soil measurement.
HI12923 is a glass body, refillable, single junction pH electrode. This electrode has a triple ceramic
junction in the outer reference cell and the conic pH sensing tip is made with low temperature glass.
There is an integrated amplifier and built‑in temperature sensor for automatically temperature com‑
pensated pH readings.

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1) Liquid Crystal Display (LCD).
2) Functional keys.
3) /keys to scroll through calibration buffers, setup options, manual temperature compensation
and logged data.
4) ON/OFF ( )key, to turn the instrument ON and OFF.
5) LIGHT ( ) key to toggle display backlighting.
6) GLP key, to display Good Laboratory Practice information.
7) CAL key, to enter/exit calibration mode.
8) SETUP key, to enter/exit SETUP mode.
9) RCL key, to enter/exit view logged data mode.
10) MODE key to change pH resolution.
11) RANGE key, to switch between pH and mV range.
12) HELP key to enter/exit contextual help.
13) ESC to leave current mode, exit calibration, setup, help. etc.
FRONT VIEW
FUNCTIONAL DESCRIPTION
Soil pH Meter

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14) Electrode quick connect DIN connector.
15) USB connector.
TOP VIEW
FUNCTIONAL DESCRIPTION

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SPECIFICATIONS
pH
Range ‑2.0 to 20.0 pH / ‑2.00 to 20.00 pH / ‑2.000 to 20.000 pH
Resolution 0.1 pH / 0.01 pH / 0.001 pH
Accuracy ±0.1 pH / ±0.01 pH / ±0.002 pH
Temperature
Range ‑20.0 to 120.0 °C (‑4.0 to 248.0 °F)
Resolution 0.1 °C (0.1 °F)
Accuracy ±0.4 °C (±0.8 °F) (excluding probe error)
mV
Range ±2000.0 mV
Accuracy 0.1 mV
Resolution ±0.2 mV
pH Calibration
Up to five point calibration, seven standard buffers available
(pH 1.68, 4.01, 6.86, 7.01, 9.18, 10.01, 12.45), and five custom
buffers
Slope Calibration From 80 to 110%
Temperature Compensation Automatic
pH Electrode HI12923 pH & temperature
LOG On demand, 200 samples (100 pH and 100 mV)
Input Impedance 10¹² Ω
Battery Type/Life 1.5V AA batteries (4 pcs.) / approx. 200 hours of continuous use
without backlight (50 hours with backlight)
Auto Power Off User selectable: 5, 10, 30, 60 minutes or disabled
PC Interface opto‑isolated USB
Dimensions 185 x 93 x 35.2 mm (7.3 x 3.6 x 1.4”)
Weight 400 g (14.2 oz)
Environment 0 to 50 °C (32 to 122 °F) max. RH 100% IP67

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pH is the measure of the hydrogen ion concentration [H+]. The pH scale goes from 0 (very acidic) to 14 (basic)
with pH 7 being neutral. Soil can be acid, neutral or alkaline.
Fig. 1. shows the relationship between the scale of pH and types of soil. Most plants prefer a pH range from 5.5 to
7.5; but some species prefer more acid or alkaline soils. Nevertheless, every plant has a target for optimum growth.
Fig. 1. Types of soil according to the pH value
pH strongly influences the availability of nutrients and the presence of microorganisms and plants in the soil.
For example, fungi prefer acidic conditions whereas most bacteria, especially those supplying nutrients to the
plants, have a preference for moderately acidic or slightly alkaline soils. In fact, in strongly acidic conditions,
nitrogen fixing and the mineralization of vegetable residual is reduced.
Plants absorb the nutrients dissolved in the soil water and the nutrient solubility depends largely on the pH
value. Hence, the availability of elements is different at different pH levels (Fig. 2).
Fig. 2. Solubility of the elements according to varying pH
SOIL pH

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Each plant needs elements in different quantities and this is the reason why each plant requires a particular
range of pH to optimize its growth.
For example, iron, copper and manganese are not soluble in an alkaline environment. This means that plants
needing these elements should theoretically be in an acidic type of soil. Nitrogen, phosphorus, potassium and
sulfur, on the other hand, are readily available in a pH range close to neutrality.
Abnormal pH values may increase the concentration of toxic elements for plants. For example, a plant may not
tolerate an excess of aluminum ions that may increase under acidic conditions.
When pH values are too far from neutral conditions a less permeable and more compact soil may result.
A Soil Management Strategy with regard to pH
• It is advisable to choose crops that are suitable for the soils pH range (e.g. in an acid soil, cultivate rice,
potato, strawberry).
• Add fertilizers that do not increase acidity (urea, calcium nitrate, ammonium nitrate and superphosphate)
or lower alkalinity (ammonium sulfate).
• A cost evaluation should be made prior to soil pH modification to determine cost of soil ameliorants versus
value of plants grown.
• pH modification may produce critical improvement in plant performance but may take too long or be short
lived.
For example, by adding lime, the effects in clay soil can last for as long as 10 years, but only 2‑3 years in a
sandy soil.
For an acid soil, we can use substances such as lime, dolomitic, limestone and marl, according to the nature
of the soil. See Table 1.
SOIL pH
Soil Ameliorants Clay soil Silty soil Sandy soil
CaO 30‑50 20‑30 10‑20
Ca(OH)239‑66 26‑39 13‑26
CaMg(CO3)249‑82 33‑49 16‑33
Ca CO354‑90 36‑54 18‑36
Table 1. Quantity (q/ha) of pure compound necessary to increase 1 unit of pH.