Technical Data - Delta Ohm Hd 8706-R1 Handbuch

TECHNICAL DATA

Measuring ranges/resolutions of the instrument:
CONDUCTIVITY: 0...199.9 µS/0.1 µS; 1999 µS/1 µS;
19.99 mS/0.01 mS; 199.9 mS/0.1 mS
TEMPERATURE: 0...+90°C (+32...+194°F) with built-in
sensor in the conductimetry cell SPT06; -50...+199.9°C
(-58...392°F) with optional TP 870 resolution 0.1°C or
0.1°F up to ±199.9°
PRECISION: ±0.5% end of scale ±0.5% of reading for
conductivity; ±0.2°C (±0.4°F) ±0.3% of reading for tem-
perature (including probe error)
TEMPERATURE COMPENSATION: automatic with
α
= 0.00...4.00%/°C
T
DISPLAY: LCD 12 mm
SYMBOLS ON THE DISPLAY: HOLD, RCD, REL, MAX,
MIN, °C, °F, µS, mS
A/D CONVERSION FREQUENCY: about 1 sec./conver-
sion
FUNCTIONS: Autorange, HOLD, storage of RCD,
MAX/MIN, relative measurements, automatic and/or
manual calibration
INSTRUMENT WORKING TEMPERATURE:
0...+50°C (+32...+122°F)
SPT06 PROBE WORKING TEMP.: 0...+90°C
HD 8706S PROBE WORKING TEMP.: 0...+60°C
POWER SUPPLY: 9V/IEC6LF22 dry battery, duration
about 100 hours with alkaline battery. Low battery charge
indicated by a "Beep" at intervals of 30 seconds
WEIGHT: about 280 gr
DIMENSIONS: 215 x 73 x 38 mm
PROBE CONNECTION: DIN 45326 8-pole connector;
connection at the B input of a possible probe with two
electrodes and cell constant 1, 0.1, 10
HD 8706-R1 MICROPROCESSOR CONDUCTIVITY
METER - THERMOMETER
Model HD 8706-R1 is a precise instrument for measuring
the electric conductivity of liquids and their temperature.
In conductivity measurements, the compensation of the
temperature coefficient α is automatic with α
T
between 0.00%/°C and 4%/°C. The instrument is sup-
plied complete with a conductimetry cell with 4 Platinum
electrodes (to eliminate polarization effects) and a built-in
temperature sensor. The possible range of measurement
of this cell is extremely wide, from a few microsiemens
(distilled water) to a fraction of Siemens (base or strong
acid). The instrument is provided with the following func-
tions: "Autorange", "Hold", manual and/or automatic cali-
bration with a sample solution (generally solutions of KCI
with a known concentration), relative measurements,
simultaneous storage (RCD) of minimum and maximum
for both conductivity and temperature, Auto-Power-Off (it
may be disabled), "Beep" to indicate that a key has been
activated. The TP 870 range of probes is available for
temperature measurements in a wider range than that
possible with the conductimetry cell.
APPLICATIONS
- checking water for agricultural uses;
- checking water for industrial cooling;
- checking distilled water;
- checking drinking water, from rivers and wells;
- checking water for fish-breeding;
- measuring the conductivity of any type of solution, even
highly alkaline or acid ones;
- conductimetry titrations;
- determining the ionic concentration, etc
A single conductimetry cell with 4 electrodes covers the
measuring range from 5 µS up to 100,000 µS.
Figura C
A
APPLICATIONS OF CONDUCTIVITY
- Chemical effluents
- Demineralizers
- Inverse osmosis
- Steam boilers
- Condensate recovery
- Waste effluents
- Boiler drain outlets
- Cooling towers
- Desalination plants
- Analysis laboratories
- Fruit peeling
- Level control
- Oceanography - Salinity
INDUSTRIES THAT USE CONDUCTIVITY
MEASUREMENTS:
- Chemical industry
- Energy production plants
- Hospitals
- Textile industries
- Iron and steel works
- Breweries
- Soft drinks manufacturers
- Mines
- Semi-conductors
- Farming
- Food industry
- Electroplating
- Paper mills
- Oil refining
- Maritime sector
Conductivity is the property a substance has of conduct-
ing electric current. The inverse of conductivity is resis-
tivi-ty. All substances have conductivity; this varies a
great deal depending on the nature of the substances,
ranging from very low values such as those for glass to
very high values for gold, copper and metals in general.
Liquids are generally made up of ionic compounds dis-
variable solved in water; their conductivity is between that of insu-
T
lating materials and metals. It may be easily measured
by electronics, providing useful information. The basic
unit for measuring resistance is the ohm; the reciprocal
of resistance is conductivity, for which the basic unit of
measurement is the "SIEMENS", with submultiples
mS/cm and µS/cm. This is the conductivity between two
opposite faces of a one-centimetre cube of material.
Conductivity of various aqueous solutions at 25°C
Pure water
Distilled water
Water circulating in boilers
Pure mountain stream water
Drinking water for towns
0.01Mol KCI Sol (Standard)
Maximum for drinking water
10% NaOH
10% H S0
2 4
31.0% HNO (known maximum)
3
When measuring conductivity the various ions present
cannot be distinguished, there is a proportional reading
under the combined effects of all the ions present, even
though some contribute more than others.
l
Concept of the cell constant
A cell for measuring conductivity may be made up as
shown in the drawing C.
The cell is made of insulating material with the exception
of the opposite faces A and B which are made of metal. If
it is filled with a conductivity solution L, the conductance
measured between the faces A and B is as follows:
G = LA/ where
l
G = conductance in Siemens
L = conductivity in Siemens/cm
= distance in cm between the electrodes or faces A
l
and B
A = surface in cm
The corresponding equation for the resistance is:
R = resistance in ohm
p = resistivity in ohm
= distance in cm between the electrodes or faces A
l
and B
A = surface in cm
/A is defined as K
The term
l
resistivity, the measuring unit of which Is the cm
The cell constant of resistivity is used for all applications,
irrespective of whether conductivity or resistivity is being
used. The result is:
As the dimensions of the cell change, the cell constant
varies with the ratio
The standards to which reference is made for measuring
conductivity are solutions with a base of potassium chlo-
ride (KCI)
According to ASTM D1125-82 standards, the data are as
follows:
CONDUCTIVITY µS/cm at 25°C
0.001
0.01
0.1
1.0
Effects of temperature
In aqueous solutions the conduction process is due to
ionic movement, the behaviour is totally different from the
behaviour of metals. Conductivity increases as the tem-
perature rises, which is the opposite of what happens in
metals but similar to what happens in graphite. The con-
duction phenomenon is influenced by the nature of the
ions and by the viscosity of the liquid. All these process-
CONDUCTIVITY es depend to some extent on the temperature and, as a
(H O) 0.055 µS/cm result, the conductivity substantially depends on the tem-
2
0.5 µS/cm perature and is expressed as a relative variation per °C
1.0 µS/cm at a particular temperature, normally with percentages
1.0 µS/cm /°C at 20°C.
50 µS/cm The conductivity figures in the readings at both high and
1.413 µS/cm low temperatures are normalized at a temperature of
1.055 µS/cm 20°C or 25°C. The reading of a solution at a temperature
355 mS/cm of 20°C or 25°C is declared.
432 mS/cm
865 mS/cm
B
A
W
perpendicular to the flow of current
2
/A where
R =p
l
2 perpendicular to the flow of current
, the cell constant of
C
-1 .
G=L/K or(K ) x G = L
C C
/A.
l
146, 93
1.408, 8
12.856, 0
111.342, 00