Steps and Standards for Gas Boiler Water Quality Testing

Determination of Chloride Ion

Pipet 100ml of boiler water into a 250ml conical flask, add 2-3 drops of phenolphthalein indicator, which should turn pink. Then titrate with sulfuric acid until colorless. Add 2-3 drops of potassium ferricyanide indicator and titrate with a silver nitrate standard solution until a cherry red color is achieved. Record the volume of silver nitrate consumed and multiply by 35.5 to obtain the standard for chloride ions: chloride ions ≤ 400.

Determination of Alkalinity

Pipet 100ml of boiler water into a 250ml conical flask, add 2-3 drops of phenolphthalein indicator, the solution will turn pink. Titrate with the standard sulfuric acid solution until the color just disappears. Then, add 2-3 drops of methyl orange indicator and continue titrating with sulfuric acid until it turns orange-red. Record the volume of sulfuric acid consumed; this value is equivalent to the alkalinity value.

Measurement of 3 Hardness

Measure 100ml of boiler water into a 250ml conical flask, add a few grains of Loheng T indicator, then add 2-3 drops of ammonia-ammonium chloride buffer solution, titrate with the EDTA standard solution until the solution changes from wine red to blue. Record the volume of EDTA solution consumed at the endpoint. This volume is equivalent to the hardness value of the boiler water.

Standard: Hardness: less than or equal to 0.03 mmol per liter for steam ovens

Water heater 0.6 mmol per liter

pH Measurement

Test with pH paper

Standard: pH: 10-12