Notes on Conductivity Meters.

Notes on Conductivity Meters.

Conductivity meters, Total Dissolved Solids (TDS) meters and resistivity meters are analytical instruments that measure the conductivity, dissolved solids, and/or resistivity of a liquid sample. They can measure a single variable, a combination of variables, or all three variables. Often, because these variables are related, combination conductivity meters, dissolved solids meters and resistivity meters used. Conductivity, a measure of water’s ability to transmit electrical current, is a gross, indirect measurement of the concentration of ions. Consequently, conductivity can be used to estimate levels of total dissolved solids (TDS), a measurement of the dry mass of dissolved solids in water. As a rule, most of the colloidal particles are included in a TDS measurement. Resistivity, another related variable, is the reciprocal of conductivity.

Specifications for conductivity meters, dissolved solids meters and resistivity meters include conductivity range, dissolved solids range, and resistivity range; conductivity accuracy, dissolved solids accuracy, and resistivity accuracy; and process media temperature. Portable, hand held, modular, lab, benchtop, field-use, and panel-mounted instruments are commonly available. These instruments have an analog meter, a digital display, or a video display such as cathode ray tube (CRT), liquid-crystal display (LCD), or flat panel display (FPD). Often, conductivity meters, dissolved meters and resistivity meters with manual controls have knobs or potentiometers. Analytical instruments with a digital front panel are programmed with a keypad. Programmable conductivity meters, dissolved solids meters and resistivity meters are also available.

Conductivity meters, dissolved solids meters and resistivity meters provide electrical outputs such as analog voltages, analog currents, and analog frequencies. Devices with a switch or alarm-relay output are also available. In terms of features, some conductivity meters, dissolved solids meters and resistivity meters are battery-powered, temperature compensated, event triggered, or designed for extreme environments. Others have filters, built-in or self-calibration, or self-test capabilities. Conductivity meters, dissolved solids meters, and resistivity meters with that provide special signal processing and/or filtering are also available. Often, these analytical instruments use Butterworth or Bessel filters. Butterworth filters provide a very flat response. There is almost no attenuation in the passband, and the roll-off rate is somewhat slower than other filters. Bessel filters have a relatively flat passband and slow roll-off.
Notes on TDS

Total Dissolved Solids (TDS) are the total amount of mobile charged ions, including minerals, salts or metals dissolved in a given volume of water, expressed in units of mg per unit volume of water (mg/L), also referred to as parts per million (ppm). TDS is directly related to the purity of water and the quality of water purification systems and affects everything that consumes, lives in, or uses water, whether organic or inorganic, whether for better or for worse.

Why Should You Measure the TDS Level in Your Water?
Some regulations advise a maximum contamination level (MCL) of 500mg/liter (500 parts per million (ppm)) for TDS, while the World Health Organisation says 1000ppm. Numerous water supplies exceed this level. When TDS levels exceed 1000mg/L it is not considered fit for human consumption. A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (lead arsenic, cadmium, nitrate and others) may also be dissolved in the water.

Even the best water purification systems on the market require monitoring for TDS to ensure the filters and/or membranes are effectively removing unwanted particles and bacteria from your water.


Notes on Water Hardness
Does hard water really create problems ?

Hard water can be a very costly addition to your home primarily because it leaves a residue called hard water scale on all washable surfaces.

Over a period of time, hard water scale can clog your plumbing which eventually reduces water pressure. It damages water heaters, dishwashers, washing machines, coffee makers and virtually all appliances through which water passes. This scale leaves spots or streaks on dishes and glassware, and dulls the look of clothing, floors, sinks, tubs, and even hair.

Corrosion often occurs because of highly acidic water that gradually eats away pipes, appliances, heaters, boilers and air-conditioning units.

Water Softeners are designed to soften water so that it washes brighter, rinses cleaner and feels much better.

High TDS indicates Hard water, which causes scale buildup in pipes and valves, inhibiting performance. Since TDS is related to water hardness, using a TDS meter can be your first step in determining the degree of hardness of the water. Generally speaking, the higher the level of TDS (ppm), the higher the degree of hardness.

Water hardness is typically reported in parts per million (ppm). .




Where Do Dissolved Solids Come From?
Some dissolved solids come from organic sources such as leaves, silt, plankton, and industrial waste and sewage. Other sources come from runoff from urban areas, fertilizers and pesticides used on lawns and farms.



Dissolved solids also come from inorganic materials such as rocks and air that may contain calcium bicarbonate, nitrogen, iron phosphorous, sulfur, and other minerals. Many of these materials form salts, which are compounds that contain both a metal and a nonmetal.



Salts usually dissolve in water forming ions. Ions are particles that have a positive or negative charge.

Water may also pick up metals such as lead or copper as they travel through pipes used to distribute water to consumers.



The efficacy of water purifications systems in removing total dissolved solids will be reduced over time, so it is highly recommended to monitor the quality of a filter or membrane and replace them when required.
With Regards,

Sebastian

G.M. Technical

Nunes Instruments

645 Hundred Feet Road,

Coimbatore. 641012.

Tamil Nadu

India,

Web: www.nunesinstruments.com

Mail: info@nunesinstruments.com



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