Delta OHM HD 8706-R1 User manual

HD 8706-R1
INSTRUCTION MANUAL

HD 8706-R1
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HD 8706-R1
ENGLISH
MICROPROCESSOR CONDUCTIVITY
METER - THERMOMETER

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1- Input A, DIN 8-pole connector. This input is suitable for the combined conduc-
tivity/temperature probe and for the TP 870 series of solely temperature
probes.
2- Symbol indicating HOLD status.
3- Display.
4- MIN symbol, the value indicated on the display is the MIN value stored by the
instrument.
5- MAX symbol, the value indicated on the display is the MAX value stored by the
instrument.
6- RCD symbol, indicates that the instrument is storing the maximum and mini-
mum value of the probe inserted in input A.
7- HOLD key; when this key is pressed the reading on the display is held while
internally the instrument continues to update data.
8- RCD key; when this key is pressed the instrument is set to store the MAX, MIN
and present values read at the probe input.
9- Key for selecting REL relative operating mode. The relative measurement is
taken with respect to the moment the REL key is pressed.
10 - Key αT, when this key is pressed the modification of the temperature coefficient
by means of the st keys is enabled.
11 - When this key is pressed temperature reading in °C or °F is selected.
12 -Key s ; this key is used during calibration to increase the value indicated on the
display.
13 - °C symbol, indicates that the reading being made is in °C.
14 - °F symbol, indicates that the reading being made is in °F.
15 - µS symbol, indicates that the reading being made is in µS (microSiemens).
16 - mS symbol, indicates that the reading being made is in mS (milliSiemens).
17 - REL symbol, indicates that a REL relative measurement is being taken.
18 - B, flashing symbol, indicates that AUTO-POWER-OFF is disabled.
19 - ON/OFF key of switching the instrument ON and OFF.
20 - DATA-CALL key; when this key is pressed the display shows in sequence the
MAX, MIN and present value of the signal detected by the probe inserted in
input A.
21 - Key ; when this key is pressed the electric conductivity of the liquid being
tested is measured.
22 - CAL key; when this key is pressed during the conductivity measurement, auto-
matic and/or manual calibration is enabled.
23 - Key t ; this key is used during calibration to decrease the value indicated on
the display.
24 - Input B, DIN 8-pole connector. This input is suitable for the temperature probes
Pt100 4 wire, or conductivity probes with cell constant K0.1 - K1 - K10.
HD 8706-R1

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KEY SYMBOLS LIT
BESIDES
THE NUMBERS
FUNCTION DESCRIPTION
All the symbols
are lit for a few
seconds after
switching on
The B symbol
flashes to
show that
AUTO POWER
OFF is disabled
HOLD
HOLD
disappears
°C/°F
REL
Switches the instrument ON and OFF.
Press once to switch on; when it is
pressed again it switches the instrument
off.
The instrument switches itself off auto-
matically about 8 minutes after this key
has been pressed. If any key other than
the ON/OFF key is pressed, the instru-
ment switches itself off 8 minutes after
the last key was pressed.
If the HOLD key is held down simultane-
ously with the ON/OFF key when switch-
ing on (held down HOLD for all the dura-
tion of the ignition), the automatic cutout
is disabled and power is supplied without
interruption.
The cutout function is also disabled dur-
ing RCD. To switch off, press the
ON/OFF key.
HOLD key.
Press this key to “freeze” the reading.
When the key is pressed again the instru-
ment leaves HOLD mode and returns to
normal functions.
This key selects the units °C or °F.
Whenever it is pressed the units °C and
°F alternate. The change may occur dur-
ing HOLD, RCD, REL and DATA CALL
modes.
Key for selecting relative measurements.
When this key is pressed the difference
(relative value) between the value (D1)
measured shortly before pressing the key
(reference value) and the next value (Dx)
is displayed.
REL = Dx - D1.

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KEY SYMBOLS LIT
BESIDES
THE NUMBERS
FUNCTION DESCRIPTION
REL
disappears
RCD
B flashes
RCD + B
disappear
Indicates
unit chosen
(µS, °C, °F)
Max µS (or °C or °F)
Min µS (or °C or °F)
Updated value
When the key is pressed again the instru-
ment returns to normal functions.
MAX/MIN storage key.
The maximum/minimum recording starts
from the moment the REC, MIN, MAX
key is pressed (the RCD symbol
appears).
When the key is pressed again the RCD
symbol disappears and the maximum and
minimum values are no longer updated.
The maximum and minimum are recorded
for both conductivity and temperature.
During RCD mode the AUTO POWER
OFF function is disabled and the B sym-
bol flashes.
Press the DATA CALL MIN/MAX key to
read the recorded values.
*The data recorded remain in the memo-
ry even if the RCD mode is abandoned
(the values can be read later). Howev-
er, when the instrument is switched off
or RCD is started again, the previous
MAX/MIN values are erased.
*When RCD MAX, MIN is pressed dur-
ing REL, the maximum and minimum
values of Dx are memorized instead of
the relative values.
Key for recalling the maximum and mini-
mum. Whenever this key is pressed the
indication on the display varies in the
order shown below.
Maximum value.
Minimum value.
Value measured at that moment.

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KEY SYMBOLS LIT
BESIDES
THE NUMBERS
FUNCTION DESCRIPTION
µS or mS
µS or mS
flashes
When this key is pressed the modification
of the temperature coefficient by means
of the keys s and t is enabled (range
0 ... 4%/°C or 0 ... 2.22%/°F).
When this key is pressed the electric con-
ductivity of a liquid is measured.
When this key is pressed during conduc-
tivity measurements, automatic and/or
manual calibration is enabled. When CAL
is pressed for the second time the calibra-
tion is confirmed. The s and t keys are
used during calibration to increase or de-
crease the value on the display.
CAL
Symbol RCD led
lights up
Store
MAX value
Store
MIN value
Press RCD
(disable)
Press RCD
(enable)
*The MAX/MIN values can be read during RCD. In this case the values
shown correspond to the dotted lines in the above figure.
2 GENERAL INFORMATION
The HD 8706-R1 is normally supplied with the combined 4-electrode and
temperature probe SPT06.
The cell measurement area is bounded by a Pocan tube. A positioning
key, directs correctly the insertion of the tube into the probe. To clean the
probe, pull the tube along the probe axle. It is not possible to take mea-
surements without this tube.

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For measuring temperature, probes are available for air (TP 870/A), for
contact (TP 870/C), with a penetration point (TP 870/P) and for immersion
(TP 870). The measuring range with these probes is from -50°C (-58°F) to
+200°C (+392°F), while with the built-in sensor in the conductimetry cell
measurements are limited to +90°C.
3 CALIBRATION
The instrument is able to recognize two standard calibration solutions:
0.1-mole solution of KCI and a 0.01-mole solution of KCI.
These solutions are on sale in specialized shops or they may be prepared
by following the procedures given below. Calibration is automatic when
using one of these two solutions. (See par. 3.1)
Manual calibration is possible using a standard solution with a different
conductivity from the solution used in automatic calibration.
PREPARATION OF STANDARD CALIBRATION SOLUTIONS
Dry the potassium chloride(KCI) at 105...120°C (221...248°F) for two
hours. For a 1-mole solution, dissolve 74.555 g KCI in one litre of deminer-
alized water with conductivity less than 3 µS/cm.
For a 0.1-mole solution, dissolve 7.456 g KCI in one litre of demineralized
water with conductivity less than 1 µS/cm.
For a 0.01-mole solution, add 100 millilitres of 0.1-mole solution to 900
millilitres of demineralized water with conductivity less than 1 µS/cm.
c0.01 M 0.1 M 1 M
T18°C 1.225 mS/cm 11.19 mS/cm 98.24 mS/cm
19°C 1.251 mS/cm 11.43 mS/cm 100.16 mS/cm
20°C 1.278 mS/cm 11.67 mS/cm 102.09 mS/cm
21°C 1.305 mS/cm 11.91 mS/cm 104.02 mS/cm
22°C 1.332 mS/cm 12.15 mS/cm 105.94 mS/cm
23°C 1.359 mS/cm 12.39 mS/cm 107.89 mS/cm
24°C 1.386 mS/cm 12.64 mS/cm 109.84 mS/cm
25°C 1.413 mS/cm 12.88 mS/cm 111.80 mS/cm

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3.1 AUTOMATIC CALIBRATION
Automatic calibration is possible with a 0.1-mole (or 0.01-mole) solution of
KCI. The temperature of the solution must be between 15°C (59°F)
and 30°C (86°F), otherwise the error signal “E3” appears.
a) Switch on the instrument by pressing the key.
b) Immerse the conductimetry cell in the sample solution so that the four
rings are covered.
c) Shake the electrode gently so that any air inside it will escape.
d) Press the CAL key. The conductivity value of the solution at the probe
temperature appears on the display. For example 1278 µS at 20°C
(68°F) and the µS (or mS) symbol flashes.
e) Press the CAL key again to confirm the value displayed (or adjust this
value with the s and t keys before pressing CAL again). The µS (or
mS) symbol stops flashing.
NOTE: When leaving calibration mode the value on the display may
increase or decrease. This happens only if the temperature of the liquid
is different from 20°C (which is the temperature at which the conductivi-
ty values are normalized). In fact, when the temperature is different
from 20°C the instrument indicates the conductivity, value with the tem-
perature compensation made according to the αT coefficient, set by the
user, which may be considerably different from the value of the calibra-
tion solution.
f) Rinse the probe in water. If measurements are later made at low con-
ductivity, we advise rinsing it in distilled or bidistilled water.
At this point the instrument is calibrated and ready for use.

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3.2 VARIATION OF THE REFERENCE TEMPERATURE
IN CONDUCTIVITY MEASUREMENTS
In conductivity measurements it is possible to change the reference tem-
perature, choosing between the values of 20°C and 25°C.
When the instrument leaves the factory it is set to operate with reference
temperature 20°C; to change to 25°C, proceed as follows:
Holding down the button, press the button until the value 20°C
appears on the display, then release the button; with every impulse
of the button the set value will alternate between 20°C and 25°C and
so on.
To confirm the desired reference temperature, press the button.
The selected value will remain stored in the memory until it is intentionally
changed.
NOTE: when the battery is changed the reference value must be set
at the desired temperature (20°C or 25°C).
3.3 MANUAL CALIBRATION
Manual calibration is possible using solutions with any conductivity. How-
ever it is necessary to know the conductivity of the solution at the tempera-
ture at which calibration is to be carried out. Follow these instructions:
a) Immerse the conductimetry cell in the solution with known conductivity
so that the four electrodes are covered with liquid. Switch off the instru-
ment by pressing the ON/OFF key.
b) Press the αTkey. The temperature coefficient used for calculating the
temperature compensation in conductivity measurements is displayed.
Using the t key, bring the value displayed to 0.00. In this way the tem-
perature compensation in conductivity measurement is excluded.
c) Take the temperature reading by pressing the °C/°F, on the basis of the
temperature determine the conductivity of the calibration solution, for
example by looking it up in a table that indicates conductivity as a func-
tion of temperature.
d) Press the key. Press the CAL key. The µS (or mS) symbol flashes. If
the conductivity of the calibration solution is close to that used in auto-
matic calibration, the instrument proposes this value. Using the s and

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t keys, set the conductivity value determined at point c. If the conduc-
tivity of the calibration solution is very different from the one used in
automatic calibration, “E1” (slope >150% of the rated value) or “E2”
(slope <30% of the rated value) is displayed. In both cases it is suffi-
cient to press the s or t key to cancel the error signal. Using the same
keys, set the conductivity value determined at point c.
e) Press the CAL key again to confirm the value displayed. The µS (or
mS) symbol stops flashing. Rinse the probe with water. If measure-
ments are later made at low conductivity, we advise rinsing it in
distilled or, better, bidistilled water.
At this point the instrument is calibrated and ready for use.
4 TEMPERATURE COMPENSATION
The temperature coefficient αTis the percentage measurement of the vari-
ation of conductivity with temperature and is expressed in %/°C (or %/°F).
The electric conductivity of a metal decreases as the temperature increas-
es, while it increases in a liquid.
There therefore arises the problem that the conductivity of two liquids can-
not be directly compared if the measurement has not been made at the
same standard reference temperature, which in chemical measurements is
20°C (25°C).
If the measurement is taken at a temperature different from 20°C (25°C),
an approximate assessment of the conductivity of the liquid at 20°C (25°C)
may be obtained by means of temperature compensation, defined by the
following formula:
where: = temperature expressed in °C
= conductivity at temperature (°C)
20 (25) = conductivity at 20°C (25°C)
αT20 =temperature coefficient expressed in
%/°C
Unfortunately the formula does not give good results if the temperature is
appreciably different from 20°C (25°C) because αTis not costant, but a
non-linear function of the temperature and the conductivity.
Also, it is not generally know before taking the measurement, unless it can
be found on tables referring to the liquid to be examined. αTmay be exper-
imentally determined by taking two measurements, one at 20°C (25°C) and
another at the temperature , having previously excluded temperature
= 20 αT
100
1 + (- 20)

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compensation (in the HD 8706-R1 this may be done by setting αTat 0.00,
see the nex paragraph). The formula for calculating αTis the following:
For the definition of the variables see figure
Definition of the temperature coefficient αT= α/ αx 100/ 20
In the HD 8706-R1 temperature compensation is automatic and therefore it
is sufficient to set the temperature coefficient αTof the liquid with the fol-
lowing procedure:
4.1 SETTING THE TEMPERATURE COEFFICIENT αT
a) Switch on the instrument by pressing the ON/OFF key.
b) Press the αTkey. Using the s and t keys, set the desired αTcoeffi-
cient. Remember that αTis displayed in %/°C (with two decimal places
X.XX) if the instrument has been set to measure in °C, while the display
will be in %/°F if the instrument has been set to measure in °F (press
the °C/°F key to change from °C to °F or vice versa).
At this point the setting of the temperature coefficient is complete.
100
20
(- 20)
αTx
=- 20



20
20 



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5 HOW TO MEASURE CONDUCTIVITY
a) Connect the connector of the conductimetry cell in the input A of the
instrument paying attention to the polarization mark. Immerse the probe
in the solution so that the four rings are covered. Shake the electrode
gently so that any air inside it will escape.
b) Switch on the instrument by pressing the ON/OFF key. If the instrument
has not been calibrated, proceed to do so (par. 3.1, page 27).
c) Set the temperature coefficient (par. 4.1, page 30).
d) Press the key to measure the conductivity of the liquid with reference
to the temperature of 20°C (25°C). If you wish to measure the absolute
conductivity (that is without temperature compensation) just set αTat
0.00 (par. 4.1, pag. 30).
e) After use rinse the probe with clean or, better distilled water.
7
3
5
61
4
8
2
Instrument Input B
HD 8706-R1
BA
7
3
5
61
4
8
2
Probe Pt100 4 wire input
73 16
Pt100
Probe SPT series input
8
KCELL
K=1
K=10
K=0.1
2 5 4
Probe SPT06 input
-5V
8
OUT
2.375mV/°C
1
GND
6
+5V
73 5 2 4
Probe Pt100 TP 870 series input
-5V
8
OUT
2.375mV/°C
1
GND
6
+5V
7
Probe SPT series input
73 16
Pt100
8 2
KCELL
K=1
K=10
K=0.1
5 4
KCELL
K = 0.1
K = 1.0
K = 10
470 pF
OPEN
SHORT CIRCUIT
Instrument Input A

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5.1 CONDUCTIVITY MEASUREMENT WITH
TWO-ELECTRODES PROBES
Two-electrodes probes with or without Pt100 temperature sensor and cell
constant K ≈K 0.1, K 1, K 10 • cm-1 can be connected to the instrument -
input B. The measuring range of these cells is indicated in the diagram
which follows:
6 APPLICATIONS OF CONDUCTIVITY MEASUREMENTS
If must always be remembered that the conductivity of a liquid is propor-
tional to the total amount of dissolved substances and not to one specific
substance. Despite these there are many applications of conductivity,
especially for quality controls.
6.1 CHECKING IMPURITIES IN WATER
The most frequent applications are in the demineralization of water, by dis-
tillation, jonic exchange or inverse osmosis. Of course it is not possible to
measure impurities that do not contribute to conductivity, such as sand, oil,
micro-organisms, etc. Good distilled water should have a conductivity of
less than a few µS.
An interesting application is the determination of impurities in sugar. Sugar
is not an electrolyte and does not contribute to a variation of conductivity if
it is dissolved in demineralied water, but impurities do.
1 10 100 10 100 1000
µS / cm mS / cm
0.1
K=10
K=1.0
K=0.1

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Conductivity of dilute solutions
Conductivity of high concentration solutions

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6.2 DETERMINING THE CONCENTRATION OF A
SOLUTION
If there is only one electrolyte in a solution, its concentration may be deter-
mined by measuring the conductivity.
For example it is shown the conductivity trend of a number of electrolytes
as a function of concentration. If the curve that gives the conductivity as a
function of concentration shows a maximum value, the concentration can-
not be determined for certain because for a given conductivity value there
are two concentration values. In this case the solution must be dissolved
so as to obtain a certain value.
If the solutions contains more than one type of electrolyte, the concentra-
tion of the individual components cannot be determined unless particular
conditions are present.
For example, an acid or a strong base contribute much more than a salt to
the increase in conductivity. Typical examples: regulation of detergent in
industrial washing, regulation of degreasing baths, regulation of galvanic
baths, checking milk, checking fertilizer in irrigation systems, etc.
6.3 CHECKING CONDUCTIVITY IN MULTI-ELECTROLYTE
SOLUTIONS
A conductimetry control often allows the chemical-physical variation of a
solution to be detected. In oceanography the total saline content may be
determined by means of conductivity measurements. In lake or river water
a variation in conductivity is often the sign of pollution due to industrial
waste water.
The hardness of the feeding water for boilers, cooling towers, steam gen-
erators, etc. may be determined approximately by means of conductivity
measurements (in Italy it is sufficient to multiply the conductivity at 20°C by
0.7 to obtain the quantity of equivalent salinity expressed in ppm of
CaCO3).
In the food industry the concentration of various saline solutions for pre-
serving food stuffs may be determined by measuring conductivity.
6.4 CONDUCTIVITY OF THE SOIL
It is a known fact that for different types of plants, flowers and cereals there
are optimum soil salinity values. Conductivity measuring allows indirect
determination of the salinity of the soil.
The method adopted by the Italian Society of Science of the Soil is the fol-
lowing:
Take a sample of soil, dry it in the air and ridles it at 2 mm. Dissolve it in
5 times its volume of demineralized water. Stir for about 30 minutes.
Let the liquid rest for few minutes and take the measurement with an

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electrode immersed in the liquid just over the soil sediment. The con-
ductivity found must be expressed in µS/cm at the temperature of 20°C
(25°C). The salinity of the soil is calculated with the formula:
where: S = salinity of the soil in 100 gr of soil
20 (25) = conductivity expressed in µS 20°C (25°C)
The measured values allow the regulation of the dose fertilizer of in the
irrigation water.
ERROR INDICATION
OL: Overload warning.
E1: The solution used for conductivity calibration is wrong because the
slope calculating gives a value >150% of the rated value.
E2: The solution used for conductivity calibration is wrong because the
slope calculating gives a value <30% of the rated value.
E3: The temperature of the calibration solution is not between 15°C
(59°F) and 30°C (86°F). Calibration is inadmissible outside this range.
METHOD OF USE
*Do not expose the probes to gases or liquid that could corrode the sen-
sor material. Clean the probes carefully after use.
*Do not bend the connectors by applying upward or downward force.
*Do not bend or deform the probes or drop the sensor for surface mea-
surements.
*Temperature probes for surfaces must be held in vertical position to the
surface. A drop of oil or silicone grease must be applied between the sur-
face and the sensor to improve the thermal contact. Do not use water or
solvents to do this.
*Temperature measurements on not metal surfaces require a great deal
of time due to their low heat conductivity.
*To obtain a reliable measurement, too rapid temperature variations must
be avoided.
*This instrument is water-resistant but not watertight, so it must not be
immersed in water. If it should fall into the water it must be taken out
immediately and checked to ensure that no water has infiltrated. The
instrument must be handled in such a way that water cannot get in at the
connector side.
0.32 • 20
S=1000

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LOW BATTERY WARNING AND BATTERY REPLACEMENT
If the battery voltage falls below acceptable levels, a beep sounds every 30
seconds. From that moment there remains about 1 hour autonomous oper-
ation, however the battery should be replaced as soon as possible.
To change the battery turn the battery retaining screw in an anti-clockwise
direction. After replacing it (with an ordinary 9V/006P battery), close the
door, inserting the tag on the door into the slot provided, and turn the
screw in a clockwise direction.
Ensure that the instrument is switched off before changing the bat-
tery.
FAULTY OPERATION WHEN SWITCHING ON AFTER
CHANGING THE BATTERY
Repeat the battery changing procedure, waiting for a few minutes to allow
the circuit condeser capacities to be completely discharged, then insert the
battery.
WARNING
*If the instrument is not be used for a long time the battery must be
removed.
*If the battery is flat it must be replaced immediately.
*Take steps to avoid leakage of liquid from the battery.
*Use good quality leakproof batteries.
Warning for sensors and probes
The TP 870 series of Pt100 temperature probes are sturdy, the element on
which the platinum wire is wound is alumina. For long life avoid hard
knocks, especially at temperatures above 400°C, or thermal shocks.
The shell is made in AISI 316 stainless steel.
In the combined conductivity and temperature probe the outer tube is
made of Pocan and the temperature sensor of Platinum.
When using, check that these materials are compatible with the liquid in
which the measurement is to be taken.
The sensor must be kept in a dry place. Check regularly that there are no
encrustations on the sensible part of the probe. Any encrustations may be
removed with a damp rag and detergent.
Particularly stubborn encrustations may be removed with kitchen type soap
pads. After you have cleaned the rings, do not touch them with your hands.

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MAINTENANCE
Storage conditions
*Temperature: -20...+60°C.
*Humidity: less than 90% relative humidity.
*Don not store the instrument in places where:
1) There is a high degree of humidity
2) The instrument is exposed to direct sunlight
3) The instrument is exposed to a source of high temperature
4) There are strong vibrations
5) There is steam, salt and/or corrosive gas.
The instrument body is made of plastic so it must not be cleaned with sol-
vents which can spoil plastic.
GUARANTEE
This instrument is strictly inspected before being sold. However if there
should be any defect due to manufactured and or transport, apply to the
dealer from whom you bought the instrument.
The guarantee period is 2 (two) years from the date of purchase. During
this period all defect found by us will be repaired free of charge, excluding
those due to incorrect use and careless handling.
The probes are not covered by the guarantee, as they can be irreparably
damaged after only a few minutes of incorrect use.

- Data communication equipment
- Data terminal equipment
MODEM
14 15 16 17 18 19 20 21 22 23 24 25
12345678910111213
SCR
TXD
RXD
RTS
CTS
DSR
GND
DCD
NC NC NC NC NC
NC
TC
NC RC NC NC
DTR
NC NC NC
TEST
NC
COMPUTER
DCE
DTE
12345
6789
12345678910111213
141516171819202122232425
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SERIAL OUTPUT FOR HD 8706-R1
To enable the serial output on the instrument, proceed as follows:
1Insert the SUB D 9-pole female connector on the adapter cable with
electronics AD RS232C in the SUB D 9-pole socket on the instrument.
2Connect the SUB D 25-pole female connector of the coupling to the
serial input of the printer or the computer.
The position of the switch inside the connector must be:
DCE: data communication equipment (Modem)
DTE: data terminal equipment (Computer).
3If you wish to send the information shown on the display (once only),
press the HOLD button until the instrument gives two beeps.
4If you wish to send the information shown on the display continuously,
at a fixed rate every 10 seconds, press the HOLD button until the
instrument gives three beeps.
5To disable the serial output during continuous transmission, press the
HOLD button until the instrument gives three beeps.
6If the serial output is not being used, it is available not to insert the cou-
pling AD RS232C in the instrument; this will allow battery saving.
7 Serial output: RS232C
Data transmission speed 300 Baud
8 data bit length
1 start bit
1 stop bit
no parity
DTE DCE
AD RS 232C