1、PH
The pH value of the boiler water is between 0 and 14. Below seven is acidic, seven is neutral and above seven is alkaline. The pH value affects scale formation and the corrosiveness of boiler water. The pH should be maintained between a minimum of 10.5 and a maximum of 11.0 to prevent acidic corrosion of boiler tubes and plates and the precipitation of scale salts prior to scale deposition.
At pH values below 5.0, water is acidic enough to dissolve boiler plate. At pH values between 5 and 9.4, pitting of the shell steel plate occurs, the rate of which depends on the amount of dissolved oxygen in the boiler.
2. Dissolved oxygen
Dissolved oxygen is caused by the solubility of atmospheric oxygen in the water supply. Aeration of municipal water supplies is usually done to remove other harmful gases. Effective aeration saturates the water with oxygen.
Most corrosion problems are directly related to the amount of dissolved oxygen in the boiler water. Elimination of the corrosive effects of dissolved oxygen can be accomplished both directly and chemically.Dissolved oxygen is removed directly or mechanically by using a deaerator or by heating the water above 180 degrees Fahrenheit.Chemical degassing is accomplished by introducing specific chemicals into the boiler that react with oxygen. Dissolved oxygen levels should be kept to a minimum, but should not exceed 0.007 mg/l at any time.
3. Sulfites
Sodium sulfite is commonly used to chemically remove dissolved oxygen from boiler water. To ensure rapid and complete removal of oxygen from the boiler feedwater system, the concentration of sodium sulfite in the boiler must be maintained at a minimum of 20 PPM (parts per million).
4.Solid
Solids can be divided into two categories: suspended solids and dissolved solids. Suspended solids are those that can be removed by filtration, while dissolved solids are solutions with water. The best test for determining the solids content of boiler water is the conductivity test.
The conductivity value of boiler water varies depending on the various ionic salts present. Conductivity values can be used to measure the total dissolved solids in boiler water and as an accurate method of controlling solids through discharge.
5. Alkalinity
The alkalinity of the boiler water should be high enough to protect the shell and plates from acidic corrosion, but not so high as to produce scaling. To provide adequate protection, the minimum alkalinity should be 200 PPM. excessive boiler alkalinity, i.e., over 700 PPM, should be avoided. Higher values will result in steel embrittlement.
6. Phosphates
Phosphates are used to react with calcium hardness in boiler water. It is best to keep the phosphate concentration in the water at 30-50 PPM so that the phosphate reacts completely with the calcium hardness entering the boiler through the feed water.
7. Hardness
In boilers, water hardness can lead to scale and sludge formation. Hardness must be removed from the make-up water of the return system. Total hardness should not exceed 50 PPM.
8. Oil
Oil can foam or combine with suspended solids to form sludge, which can cause the boiler plate to overheat. If oil enters the boiler, the boiler should be taken out of service immediately and thoroughly cleaned.
ERUN-ST7-11 Series Laboratory Benchtop Boiler Water Quality Analyzer developed by Erun Environmental Protection Corporation，A comprehensive range of functions enables accurate measurement of a number of water quality parameters including turbidity, hardness, total alkalinity, pH, conductivity, dissolved oxygen content, iron ion concentration, copper ion concentration, dissolved solids content, phosphate concentration and chloride ion concentration.This analyzer is widely used in stationary steam boilers, steam and water boilers, and hot water boilers to monitor the quality of various types of water, such as feed water, boiler water, steam return water, and make-up water, to ensure the accuracy and breadth of water quality testing.
