Conductivity Meters

GAOTek conductivity meters report the conductivity of a substance as an inverse function of resistivity. Resistivity is measured in ohms/cm, while conductivity is measured in mhos/cm. Our instruments are ideal for water conditioning, medical, beverage, laboratory, and other industrial applications. GAOTek’s high-performance conductivity meters are reliable, high quality, accurate and affordable pieces of equipment that facilitate easy inspection and testing. They are compact, easy to carry, portable instruments that allow a user to conveniently work in complex conditions on-site.

Technologies

Measurement of conductivity is a widespread and useful technique for quality control in applications such as testing water purity, checking water quality, estimating the total number of ions in a solution and measuring components in process solutions. Conductivity instrumentation is a primary parameter of a monitoring program. In some applications conductivity is measured in units of resistivity, which is the inverse of conductivity. Some applications require measurement of total dissolved solids. In our devices conductivity is measured as a factor of the level and types of ions present. These meters are reliable, sensitive, and affordable devices.

A conductivity meter applies an alternating current (I) at an optimal frequency, to two active electrodes, and measures the potential (V). Then conductance (I/V) is calculated using the current and potential measurements. Conductivity meter uses conductance and cell constant to display the value for conductivity.

There are many factors that influence measurement of conductivity, such as polarization, cable resistance, geometry, frequency change and temperature.

Polarization occurs when an electric current is passed through electrodes in a solution. This may cause an accumulation of ions near electrode surfaces, causing chemical reactions at the surfaces. The resistance of polarization may lead to erroneous results.

When measuring outside the pole, errors may occur if the measuring field falls outside the geometry space. This can affect the field lines if an object intercepts these field lines.

When polarization is negligible compared to the resistance of the solution, low frequencies are applied, especially at low conductivities. This reduces the cable capacitance effect, which is greater when conductivity is low. However, all cables have a definite length and resistance, which can add to errors. A shielded cable also has some capacitance, and cable capacitance of such cables is not negligible when conductance is low.

Thus, it is recommended that a conductivity meter must be calibrated frequently for accurate measurements. It is difficult to provide a calibration interval, as the interval for conductivity cells depends on the application it is set on, samples, and the operating conditions in use. However, a cell constant value must be ascertained. It is also recommended that the thermostat, the surroundings, and the calibration must be as close as possible, to make sure that all the poles in a conductivity cell are covered.

Features

GAOTek conductivity meters are reliable, accurate, and easy to use devices. Their features include:

  • Large LCD display
  • Linear or pure water compensation for measurement accuracy
  • Automatic temperature compensation for accurate readings over the entire range of conductivity meter
  • Calibration due reminder
  • A stability indicator to automatically display the current measurement status
  • Auto-hold function to freeze stable measured values for easy viewing and recording
  • Operations guide
  • USB communication interface for data transfer
  • Multi-mode power scheme (battery, power adapter, computer’s USB port)
  • Built-in temperature sensors that allow the meter to adjust conductivity readings according to the changes in solution temperature
  • Microprocessor-based chip and parts apparatus joined with SMT technology for high performance and stability
  • Selectable cell constant (0.1/1/10), temperature coefficient and TDS conversion factor

Applications

A conductivity meter is used in various applications such as:

  • In applications where conductivity primarily depends on the presence of ions in the solution, such as monitoring water purity, checking drinking water quality and processing water quality.
  • In applications where conductivity depends on resistivity measurements, such as water contamination in organic solvents.
  • In the paper industry where total organic and inorganic dissolved solids in water are accurately measured.
  • For monitoring and determining the quality of high purity water in single point and differential leak detection.
  • In applications where acids and bases are used.
  • For salinity measurement which is proportional to conductivity especially in food.
  • For checking quality of the water used to clean electronic components, where even a tiny amount of impurity in water can cause serious impact on product quality.

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