1.Measurement of water samples of JD > 0.5mmol/ L, such as measurement procedures of boiler water, clarified water and raw water etc..Take 100 ml water sample and put it in the conical flask, add 2 ~ 3 drop 1% phenolphthalein indicator, use 0.05 mol/L sulfuric acid standard solution for titration, until the water solution turns to colorless from red, record H2SO4 consumption volume a; In addition, continue to drop 2 drops of methyl orange indicator, continue use sulfuric acid standard solution for titration until the solution turns red. Record the second sulfuric acid consumption volume of b( excluding a ).
2. Measurement of water samples of JD < 0.5mmmol/L, such as the measurement procedures of condensation water, demineralized  water and water supply:  Take 100 ml water sample in the conical flask, add 2 ~ 3 drop 1% phenolphthalein indicator, at this moment, if the solution is in red color, use 0.005 mol/L sulfuric acid standard solution for titration, until the water solution turns to colorless, record -consumption volume a of sulfuric acid; In addition, drop  2 drops of methyl red - methylene blue indicator,  continue to use sulfuric acid standard solution for titration, when the solution becomes purple from green,  record the consumption of sulfuric acid volume b( excluding a)
The alkalinity calculation is as follows:

                                     a·c×2
        Palkalinity=                                ×1000 mmol/L
                                        V
                               （a+b）·c×2
        Malkalinit=                                ×1000 mmol/L
                                        V
       Where：
        Palkalinit—showing phenolphthalein alkalinity，mmol/L.
        M Palkalinit—showing total alkalinity，mmol/L.
        C—showing the molar concentration of H2SO4 for titration，mol/L.
        V—showing the molar concentration of the water sample，mL.)