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Water analysis technology

Example: cooking salt

If cooking salt (NaCl) is added towater the salt then breaks down intoits components (ions) Na+ and CI–.Ions are charged particles and areresponsible for the electricalresistance of the water.

The conductivity provides infor-mation on the total number ofdissolved, charged components.

If, for example, the conductivity in a lake has increased during aspecific time the number ofparticles dissolved has alsoincreased.

Analytical instruments areonly as accurate as thesensor used to perform themeasurements. Whenmeasuring pH or conductivityonly those probes suited tothe particular substance canguarantee an accuratemeasured value.

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nspH electrodes/conductivitymeasuring cells and theirapplications

Universal electrode, type 01 pH + + + 0 – – 0 0 0 0 – – – 0 – – – – – 0 0 0 0 + 0 0 – – 0 – 0 – 0 pH

Lab. electrode, type 02 pH 0 + + 0 – – 0 0 0 + – – 0 0 0 0 0 – 0 + 0 0 + + 0 0 – – 0 0 + 0 0 pH

Universal electrode, type 04 pH + + + 0 – – 0 0 0 0 – – – 0 – – 0 – – 0 0 0 + + 0 0 – – 0 – – – 0 pH/°C

Special electrode, type 05 pH + + 0 + – 0 + + + + – – 0 + – – 0 – – 0 0 + + + + + + – 0 0 – – 0 pH/°C

Penetration electrode, type 03 pH 0 0 0 0 + + + + + – 0 0 – 0 – + – + + – + – + 0 + + + 0 0 0 – – – pH

Robust penetr. electrode, type 13 pH 0 0 0 0 + + + + + – + + – 0 – + – + + – + – + – + + + + 0 0 – – – pH

Conduct. meas. cell, type 07 mS + + + + – + + 0 0 0 – – 0 + – – + – – + + + + + + 0 0 – 0 0 – – + mS/°C

Conduct. meas. cell, type 10 mS + + + + – + + 0 0 0 – – 0 + – – + – – + + + + + + 0 0 – 0 0 – – + mS/°C

Key: + suitable 0 suitable in certain cases – not suitable

An exact analysis of the contents inthe laboratory will reveal the causeof this alarming increase. Perhapssewage was discharged into thelake.

– fully automatic temperaturecompensation with the help of atemperature sensor integrated inthe measuring cell

– the display and documentationof measured and calibrated data

Conductivity measuring cells

The 4 electrode measuring techno-logy in our sensors enables anextensive measuring range to becovered with only one measuringcell. It also prevents the measuredvalues becoming distorted by theformation of physical coatings,such as in waste water for example,ensuring accurate results everytime.

4 electrode cells do not requirereplating unlike 2 electrode cellswhich means they have an almostunlimited lifetime.

What is conductivity?

For electric conductivity electricalresistance is measured between twoelectrodes e.g. in a liquid.

The lower the resistance the higherthe conductivity and vice versa.Substances such as salt dissolvedin water lower the electricalresistance thus increasingconductivity.

Testo conductivity measuringsystems guarantee problem-free conductivitymeasurement due to:

– a robust and user-friendlyhandheld instrument with simul-taneous display of conductivity(referred to reference tempera-ture) and the temperature of theproduct being measured

– the adaptability of the measuringsystem to different measuringsolutions on account of itsadjustable temperaturecoefficient

– a robust measuring cell with 4electrode measuring technologyto protect from disturbinginfluences caused bypolarisation effects

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In conventional electrodessuspensions and emulsions as wellas solutions containing proteins orsulphides can block the very manysmall pores in the diaphragm. The Single Pore Diaphragm, sensortype 05 pH, has proved to be highlyeffective for such criticalapplications. It consists of a singlelarge pore which cannot becomeblocked due to the wide diameter ofthe pore. Quick response times andcorrect measured results aretherefore guaranteed.

The hole diaphragm, type 03, isideal for accurate measurements insolids or semi-solids (e.g. food). It consists of a very large “pore”therefore offering the advantagesmentioned above in substancessuch as meat or cheese.

pH electrodes

• Greater penetration powerpossible.

• Robust 5 mm cable with PUR coating.

• Short response time. Not affected by dirt thanks tohole diaphragm. With food-proof electrolyte.

• Ergonomic handle design makesyour work easier.

• The new T-handle designprevents buckling.

• pH glass embedded in break-proof plastic sleeve.

• Cardanic storage of tip in plasticcoating. Bending forces on tipdo not pose a problem. Lesschance of breaking glass! Patentpending.

pH is the abbreviation of the Latinexpression “pondus hydrogenii”(pondus = pressure, hydrogenium= hydrogen).

New robust pH penetration probe for testo 230

It is therefore a measure for theactivity of the hydrogen ions in asubstance. The activity isconnected directly to its acidic,neutral or alkaline character.

Examples of the pH values of everyday substances

acidic neutral alkaline

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Gastric juice

Lemon juice

Sour milk, yoghurt

Ion free water

Hard well water

Suds

Lime water

1M NaOH

Definition of the pH value

Why you should choose water analysis instruments from Testo

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