pH meter potentiometric method for the determination of the principles of the pH of the solution is the most basic method. PH measurement principle of the potential from the Nernst equation. Such as the one pair of reversible hydrogen ion electrode and a reference electrode into the solution, the composition of the original battery. Since the primary battery than the reference potential of the electrode under certain conditions is constant, then the value of the electromotive force of the galvanic cells with the test solution on the hydrogen ion activity becomes. Thus, by measuring the electromotive force to use the original battery meter PH / ORP meter, the solution pH in the calculation. According to the Nernst equation the electrode potential is: E = E0 + 2.3026 RTFlgaH + = - 2.3026RT F pH (1) where E0, is the standard hydrogen electrode potential, which is a predetermined 0; R is the gas constant (8.31J? K-1mol-1); T is the thermodynamic temperature (27* + t) ℃; F is the Faraday constant (9.649 × 104mol-1); aH hydrogen ion activity. 2.3026RT / F is called the theory of the hydrogen ion electrode reversible electrochemical conversion factor. When the measured pH value changes an electric potential, due to the R and F are constants, and therefore the electrode potential is a function of temperature [2]. Single potential is measured out, and only the use of the reference electrode, at a certain temperature can only be measured, which measured the pH of the test solution. pH meter works much as pH of the water of dissolved substances may be, so the pH value can be sensitive to changes in circumstances indicate that the water quality. pH changes have a significant impact on biological reproduction and survival, but also seriously affect the activated sludge biochemical effects that affect the treatment effect, pH value of the water is generally controlled between 6.5 to 7. Water is chemically neutral, some water molecules spontaneously decomposed according to the following formula: H2O = H ++ OH-, i.e., decomposed into hydrogen ions and hydroxide ions. In neutral solution PH meter / ORP meter works, hydrogen ions H + and OH- concentration of hydroxyl ions are 10-7mol / l, pH value is the hydrogen ion concentration of the negative base 10 logarithm: pH = -log, therefore the pH neutral solution is equal to 7. If there is an excess of hydrogen ions, the pH value of less than 7, the solution was acidic; conversely PH meter / ORP meter, an excess of hydroxyl ions, the solution alkaline. The pH is usually measured by potentiometric method, often with a constant potential reference electrode and the measuring electrode form a galvanic cell, the size of the primary battery electromotive force dependent on the concentration of hydrogen ions, but also on the pH of the solution. Have a special role in the measurement of the pH electrode responsive instrument glass probe PH / ORP meter, it is able to conduct electricity, hydrogen ions can penetrate special glass made with high accuracy, good anti-jamming features. When the glass probe and hydrogen ions in contact, it creates potential. Potential of the reference electrode is measured to control the silver chloride by suspension in a solution of silver. different pH values, the corresponding potential to produce not the same, by the transmitter to convert it into a standard 4 ~ 20mA output. Changzhou instrument PH / ORP meter, PH meter / ORP meter, a hundred to a hundred technology provided by Changzhou Technology Limited. Changzhou Best Technology Limited (www.czbckj.com) strong, credible, in Changzhou, Jiangsu chemical instrumentation industry has accumulated a large number of loyal customers. The company better work attitude and continuous improvement will lead one hundred innovative ideas into technology and you hand into the brilliant, for a better future!