Calibration conductivity meters

Figure 14-9 also shows a flowchart for analysis of wet and dry precipitation. The process involves weight determinations, followed by pH and conductivity measurements, and finally chemical analysis for anions and cations. The pH measurements are made with a well-calibrated pH meter, with extreme care taken to avoid contaminating the sample. The metal ions Ca, Mg, Na, and are determined by flame photometry, which involves absorption of radiation by metal ions in a hot flame. Ammorda and the anions Cl, S04 , NO3 , and P04 are measured by automated colorimetric techniques. 

Conductivity was measured as described (10) using a conductivity meter (Radiometer, Copenhagen, Denmark) type CDM3 equipped with a CDC 304 immersion electrode with manual temperature compensator type CDA 100. The instrument was calibrated as specified by the manufacturer. The determination of the (NH4)2S04 concentration from the conductivity measurements was done at constant temperature (4°C) using a calibration curve, in the range of 0.016 mM to 120 mM AS in glucose or sucrose (total... 

Conductivity Meter. A second system utilizes a simple ohmmeter circuit, shown in Fig. 3. A meter, transformer secondary winding, and conductivity cell are connected in series so that the current is a function of the cell conductance. The meter may be calibrated in resistivity or conductivity units. 

The timescale over which the conductance of the medium changes is a fundamental issue standard conductivity cells are designed for use with alternating current (AC), but the period of this current imposes a limit on rates of reactions that can be followed. To investigate reactions faster than the AC conductivity cell can handle, it is necessary to build and calibrate appropriate direct current (DC) conductivity cells, which is not a routine business. Conductivity meters that record continuously are uncommon. Nowadays, however, it is easy to interface a simple apparatus to a computer and collect the data with ad hoc software. 

SEC is measured with a conductivity meter, which normally consists of an AC bridge and a conductivity cell or electrodes. The conductance is measured between two electrodes. Two solutions of known conductivity should be used, one to calibrate the metre and the other to check the slope. It is important to correct all data for water temperature, either by calculation or by automatically using the metre s auto-temperature correction mode, since SEC is highly dependent on temperature. SEC increases by about 2% per degree centigrade rise in temperature due principally to an increase in water viscosity. 

A calibration schedule details the calibration of balances, volumetric glassware, automatic pipettes, thermometers, pH and conductivity meters, wavelength and photometric scales etc. The schedule consists of periodic external checks, employing a suitably accredited calibration service, supported by more regular in-house performance checks. 

The measurement of pg requires a pressure transducer system that is not influenced by the electric power used for the plasma polymerization, particularly when a high-frequency radio frequeny power is employed. Some pressure transducers that give pressure readouts independent of the nature of a gas are ideally suited for plasma polymerization. Some electronic gauges the readout of which depends on the nature of the gas (e.g., thermal conductivity) do not provide accurate readings of Pg because in most cases the composition the gas mixture in the LCVD reactor is unknown and there is no way to calibrate the meter for an unknown gas mixture. 

A salt A is soluble in a solvent S. A conductivity meter used to measure the solute concentration in A-S solutions is calibrated by dissolving a known quantity of A in S, adding more S to bring the solution volume to a fixed value, and noting the conductivity meter reading. The data given below are taken at 30°C ... 

The specific conductance (L or K) or conductivity of a solution is always obtained by measuring the resistance (R) of the solution taken in a suitable container of known dimensions called conductivity cell, the cell constant of which has been determined by calibration with a solution of accurately known conductivity e g. a standard KCl solution. The instrument used for electrical conductivity measurement is known as conductivity bridge. A typical system consists of an alternating current (A.C.) Wheatstone bridge, a primary element of conductivity cell and a null balance indicator (as in solubridge ) or an electronic eye as in the conductivity meter. 

Conductivity meters have been relatively easy to reduce in size and there are now a number of companies producing handheld meters. One example is the Enterprise 470 conductivity meter from Jenway (Figure 7.25). This meter is small and lightweight (370g). It also measures total dissolved solids (TDS). Direct calibration is possible on standard solutions... 

Water quality is an issue of international concern due to increasing contamination from a variety of sources. The most common types of water examined are surface waters, ground waters and waste waters. Common indicators of the quality of water are conductivity, pH, ion and nutrient measurements. The HI-991300 from Sheen Instruments Ltd (Figure 8.9) is a portable conductivity meter that measures conductivity as well as total dissolved solids (TDS), temperature and pH. For conductivity, it has a range from 0-3999 pS/cm with a resolution of 1 pS/cm. All readings are compensated automatically for any temperature variation. Calibration is carried out manually with provided solutions. The device can be operated with one hand and the rubber keypad is splash-proof. The HI-991300 is supplied complete with a conductivity probe with a one meter screened cable, a wrist strap for safety and the 9 V battery. 

Twin Cond is a conductivity meter, available from HORIBA Jobin Yvon, which features a waterproof flat sensor. Twin Cond can measure the conductivity of a solution from a single drop of sample and is therefore very suitable for both field measurements in rivers and lakes and for rain samples. It features a measurement range from 1 p,S/cm to 19.9 mS/cm. It also has one-touch auto-calibration, automatic temperature conversion and a salinity conversion function (from 0-1.1 %). Multiparameter meters can test for pH, conductivity, total dissolved solids and temperature in the one device. 

The determination of riser and downcomer [/l is often accomplished using a tracer technique or specially calibrated flow meters and mathematical relationships to convert the measurable Vl to I/l- The tracer techniques commonly used to determine Vl are based on determining the time it takes for a given tracer to travel a set distance. For example, a potassium chloride salt tracer and conductivity electrodes are commonly used to measure the time it takes an injection of the salt solution to travel past two fixed locations from which Vl is calculated (Bello et al.. 

Take a sample and check the specific gravity of the dilute solution. Use specific gravity to check and re-calibrate the conductivity meter readjust the set-point... 

Conductimetry Conductivity meter material must be calibrated separately Requires the presence of a low concentration of a... 

The concentration of ionic constituents measured by electrical conductivity typically uses a dual-electrode probe [21] submerged in the chemical solution. Temperature compensation is important so that the reported conductivity values are consistently adjusted to a standard reference temperature. Conductivity meters/probes are calibrated with the National Institute of Standards and Technology traceable calibration standards in the conductivity range of the measurement suited for the conductivity of the chemical measured. 

Some flow calorimeters (continuous calorimeters) make use of air as a heat transfer medium in other cases, gases or liquids react with each other or are products of the reaction. In the latter case, a possible approach to the measurement of amounts of substances consists in allowing the newly formed phase (usually a gas) to leave the system via a flow meter. Here the flow rate provides a measure of the quantity of substance transformed per unit time. Usually a pressure difference is the measurand as in capillary flow meters or is caused by the back pressure of the measuring instrument however, the possibility of pressure rises (caused by a buildup ) in the vessel must be taken into account. Other techniques for measuring amounts of gas make use of displacement gas meters, turbine meters, or ultrasonic meters. In these cases, the volume flow is the measured quantity. For measuring the mass flow, Coriolis or thermal mass flow meters can be used. In any case, it is very difficult to reduce the uncertainty of flow measurements below approximately 1%. This can only be achieved in exceptional cases when great effort is made to calibrate the meter with fluids of similar and known thermophysical properties (e.g., heat capacity, thermal conductivity, viscosity, density, etc.). 

S. Harmon, M. Hall, L. Henderson, and P. Munday, Calibration of commercial conductivity meters for measuring small items, lEE Proceedings-Science, Measurement and Technology, vol. 151, no. 5, pp. 376-380, 2004. 

For flow rate measurements the volume or, more conveniently, the mass flow is suitable. In the first case a pressure- and temperature-dependent calibration is necessary if the gas does not show ideal behavior. This also applies for heat conductivity as the measured quantity often used in flow meters. Currently, real pressure- and temperature-independent measurement of a hydrogen mass flow of a hydrogenation remains problematic on the laboratory scale, at least for low substrate concentrations. 

The airborne monitoring program concentrated on the measurement of ozone to provide supplementary air quality data for various altitudes over the fixed sites. The airborne measurements were conducted in a C-45 aircraft that carried a solid-face chemiluminescent ozone monitor. The ozone meter was cycled every 2 min to provide calibration, purge, measurement, and purge at equal intervals. The sparseness of the airborne data precluded... 

All required sensors (temperature, pressure, conductivity, how meter, etc.) in contact with the process waters must be the sanitary type, connected by tri-clamp, and well mounted (temperature). The length of the electrical connections must be long enough to allow the calibration of the sensors. 

Rinse twice and fill the polyethylene decanters with stream water, place the electrodes in water and measure the pH and conductivity with calibrated meter (mark with permanent drawing ink marker two decanters for pH and conductivity). 

Field portable temperature, conductivity, and pH meter with a flow-through cell and calibration standards... 

Conductivity is measured in the field with a portable probe. It is typically part of the temperature and pH meter, enabling us to measure all three parameters simultaneously. The meter software will perform the temperature correction to 25°C. The probe calibration is verified with a standard prepared as a solution of potassium chloride of a known conductivity. For better accuracy, field meters may have up to four different ranges of conductivity measurements, for example, 0-20pmho/cm ... 

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