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DC/DC
CONTROLS
- 6 key membrane keypad
DISPLAY TYPE AND RATE:
- 2 line x 16 character LCD. Displays menus and readings in analog and digital form with frequency used.
- Digital : Approximately once per second
- Analog : 5 times per second
SENSITIVITY
- 0.1 S/m in INDUCTIVE MODE with appropriate sensors
- 0.1 ohm in GALVANIC MODE
DYNAMIC RANGE
- INDUCTIVE MODE - 10-1 to 105 S/m
- GALVANIC MODE - 0.1 to 106 ohms
SENSOR FREQUENCY
- Inductive mode - 15.625 kHz to 2 MHz
- Galvanic mode - DC
SENSOR TYPE
- Flat coil for planar measurements and test leads for GALVANIC measurements as standard.
- Optional Air cored coils specific to standard core sizes.
RESPONSE TIME
- Less than 1 second after zeroing has been performed. (Zeroing takes 10 seconds).
OPERATING MODE
- Single or Continuous Reading
STORAGE INTERVAL
- Continuous at 1,2,10,30s,1,2min, or on command
MEMORY
- 10,000 readings in a circular buffer.
DATA OUTPUT
- RS232 ASCII format giving sequence number, conductivity and frequency.
BAUD RATET
- Selectable 300 to 9600 baud.
POWER SOURCE
- 4 x 1.5 Volts "AA" Alkaline Batteries
BATTERY LIFE
- 6 hours continuous operation at 50mA.
- Low battery indicator and auto shutdown provided.
METER CASE
- Water Resistant - 'O' ring seal
TEMPERATURE RANGE
- Operating : 0 to +50 degrees Celsius
- Storage : -40 to +60 degress Celsius
RELATIVE HUMIDITY
- 10 to 90 percent (non-condensing)
DIMENSIONS
- 100mm x 180mm x 45mm with standard coil.
WEIGHT
- Approx. 600 grams
STANDARD ACCESSORIES
- Sturdy Plastic 'Pelican' Carrying case
OPTIONAL ACCESSORIES
- Sensor coils to suit AQ, BQ, NQ, HQ, PQ cores.
- Special sensors to order.
- Sturdy field case for optional coils.
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 GCM-2 Hand-held Conductivity Meter
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This world first, hand-held conductivity meter designed by Geo Instruments,
measures the inductive and galvanic conductivity of rock samples, mine faces and drill-core.
It is used to assist in the interpretation of field data from electromagnetic surveys. Its design
and implementation results from research on the conductivity of sulphide ores and rocks sponsored by the
Australian Mineral Industry Research Association (AMIRA).
PRINCIPLE OF OPERATION
Since the impedance of an inductor will alter when placed in close proximity to a conductive body,
the GCM-2 measures the in-phase and quadrature components of this impedance change and calculates
the conductivity. A large dynamic range is obtained by utilising a measuring frequency appropriate
to the conductivity and correcting for magnetic effects.
KEY BENEFITS
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Wide dynamic range from 10-1 to 105 Siemens per metre
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Digital and analog display readout with autoscaling
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Coil sensors for drill-core measurements
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Capability of galvanic measurements to supplement the induced measurements
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Corrects for magnetic effects of samples
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Memory for 10,000 readings
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RS-232 Output
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CONDUCTIVITY VALUES OF ROCKS AND ORES
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It is important for users of the GCM-2 to note that the measured values of conductivity of rock
samples will not be the same as quoted values for pure minerals. They will generally be much less.
The reason for this is that the conductivity of a heterogeneous sample of many different minerals and
gangue varies greatly depending on the relative proportions of each mineral and the texture of the
rock, it's moisture content, etc. Gangue minerals such as quartz are in fact insulators and a typical
proportion greatly reduces the overall measured conductivity. Measurements on rock samples rarely
give values more than 104 S/m and generally range down to 1 S/m. Values of the order of 100 S/m are
most typical and values greater than 105 S/m are not observed.
The range of measurement of the GCM-2
(10-1 to 105 S/m) has been arranged to cover these typical values. Instances of where the values would
exceed the maximum value of the GCM-2 (105 S/m) would be pure metals such as native silver, gold,
copper and iron. As pyrrhotite and graphite are very good conductors, their presence in a rock sample
increases the conductivity. The texture of minerals can generate anisotropy which results in the measured
values being apparent and not true values. Anisotropy will cause the conductivity measured by
inductive means to be different from those measured galvanically. A difference between galvanic
and inductive measurements is therefore an indicator of anisotropy.
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Copyright
© 1998 IRIS Instruments
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