Request for water quality standards for softened water and central air conditioning chilled water
Thread Content
Dear all, I am in urgent need of the water quality standards for softened water output, as well as those for the chilled water used in central air conditioning systems. Thank you
There is a standard for softened water quality; you can take a look. For the original text, visit: http://www.sjzhtwy.com/blog/post/26.html. This standard specifies the water quality requirements for industrial boilers during operation. This standard applies to fixed steam boilers and steam-water dual-purpose boilers that use water as the working medium and have a rated outlet steam pressure of 2.5 MPa or less. It also applies to fixed pressurized hot water boilers and atmospheric pressure hot water boilers that use water as the working medium. II. Water Quality Standards
1. For feed water in steam boilers and dual-purpose steam and water boilers, external chemical water treatment is generally required, and the water quality shall meet the specifications in the following table:
| Parameter | Feed Water | Boiler Water |
|--------------------|------------|--------------|
| Rated steam pressure, MPa | ≤1.0 | >1.0 | >1.6 | ≤1.0 | >1.0 | >1.6 | ≤1.6 | ≤2.5 | ≤1.6 | ≤2.5 |
| Suspended solids, mg/L | ≤5 | ≤5 | ≤5 | | | | | | | |
| Total hardness, mmol/L1) | ≤0.03 | ≤0.03 | ≤0.03 | | | | | | | |
| Total alkalinity, mmol/L | | 6–26 | 6–24 | 6–16 | | | | | | |
| With superheater | ≤14 | ≤12 | | | | | | | | |
| pH (25°C) | ≥7 | ≥7 | ≥7 | 10–12 | 10–12 | 10–12 | | | | |
| Dissolved oxygen, mg/L3) | ≤0.1 | ≤0.1 | ≤0.05 | | | | | | | |
| Dissolved solids, mg/L | Without superheater: <4000, <3500, <3000 | With superheater: <3000, <2500 |
| SO2-3, mg/L | 10–30 | 10–30 | | | | | | | | |
| PO3-4, mg/L | 10–30 | 10–30 | | | | | | | | |
| Relative alkalinity, free NaOH/dissolved solids | <0.2 | <0.2 |
| Oil content, mg/L | ≤2 | ≤2 | ≤2 | | | | | | | |
| Iron content, mg/L6) | ≤0.3 | ≤0.3 | ≤0.3 | | | | | | | |
1) The basic unit for hardness in mmol/L is c(1/2Ca2+, 1/2Mg2+); the same applies hereinafter. 2) The basic units for alkalinity in mmol/L are c(OH-), 1/2CO3^2-, and HCO3-, the same applies hereafter. For boilers that have low requirements regarding steam quality and do not include a superheater, the upper limit for the alkalinity value can be appropriately increased, provided that the user obtains approval from the local boiler and pressure vessel safety supervision authority. 3) Deoxidization is required when the rated evaporation capacity of the boiler is 6 t/h or more. For boilers with a rated evaporation capacity of less than 6 t/h, deoxidization measures should be applied to the feedwater in case of local corrosion; the oxygen content in the feedwater supplied to turbines should be less than or equal to 0.05 mg/L. 4) If it is difficult to determine the dissolved solids, conductivity or chloride (Cl-) levels can be used as indirect indicators; however, the ratio between dissolved solids and conductivity, or between dissolved solids and chloride (Cl-), should be determined through experimentation. The ratio should also be rechecked and adjusted regularly. 5) The relative alkalinity of fully welded structure boilers can be left uncontrolled. 6) Only for fuel and gas boilers 2, as well as steam boilers and combined steam-water boilers with a rated evaporation capacity of 2 t/h or less and a rated steam pressure of 1.0 MPa or less (provided that there are no special requirements regarding the quality of steam and water), can in-boiler chemical treatment be employed. However, strict supervision must be exercised over scaling, corrosion, and water quality in the boiler; proper dosing, sludge removal, and cleaning procedures must be carried out, and the water quality must meet the requirements specified in the table below. Parameters: For water supply to boilers, the suspended solids level should be ≤20 mg/L; total hardness should be ≤4 mmol/l; total alkalinity should range from 8 to 26 mmol/l; the pH value at 25°C should be ≥7 and between 10 and 12. The dissolved solids level should be less than 5000 mg/L. For pressure-rated hot water boilers, external water treatment is required. For non-suspended pressure-rated hot water boilers with a rated power of 4.2 MW or less, as well as atmospheric-pressure hot water boilers, internal chemical treatment can be used; however, close monitoring of scaling, corrosion, and water quality is necessary, and proper chemical treatment must be carried out. The water quality must meet the specifications outlined in the table below. Items: In-boiler chemical treatment, External chemical treatment. Feed water, Boiler water, Feed water, Boiler water. Suspended solids, mg/L: ≤20, ≤5. Total hardness, mmol/L: ≤6, ≤0.6. pH (25°C): 1) ≥7, 10-12, ≥7. Dissolved oxygen, mg/L2): ≤0.1. Oil content, mg/L: ≤2, ≤2. 1) The pH value of the boiler water is controlled between 10 and 12 by adding chemicals. 2) The feed water for pressure hot water boilers with a rated power of 4.2 MW or more should be deoxygenated; the feed water for pressure hot water boilers with a rated power of less than 4.2 MW and atmospheric pressure hot water boilers should also be deoxygenated as much as possible. 4. For DC (through-flow) boiler feed water, external chemical treatment should be employed, and the water quality shall comply with the standards specified in Table 1 for a rated steam pressure of greater than 1.6 Mpa and less than or equal to 2.5 Mpa. 5. The water quality specifications for waste heat boilers and electric heating boilers shall meet the requirements of boilers of the same type and with the same parameters. 6. The water quality testing methods shall be carried out in accordance with Appendix A (the appendix to the standards). Common boiler water treatment equipment: boiler water softening equipment, fully automatic sodium ion exchangers
1. For feed water in steam boilers and dual-purpose steam and water boilers, external chemical water treatment is generally required, and the water quality shall meet the specifications in the following table:
| Parameter | Feed Water | Boiler Water |
|--------------------|------------|--------------|
| Rated steam pressure, MPa | ≤1.0 | >1.0 | >1.6 | ≤1.0 | >1.0 | >1.6 | ≤1.6 | ≤2.5 | ≤1.6 | ≤2.5 |
| Suspended solids, mg/L | ≤5 | ≤5 | ≤5 | | | | | | | |
| Total hardness, mmol/L1) | ≤0.03 | ≤0.03 | ≤0.03 | | | | | | | |
| Total alkalinity, mmol/L | | 6–26 | 6–24 | 6–16 | | | | | | |
| With superheater | ≤14 | ≤12 | | | | | | | | |
| pH (25°C) | ≥7 | ≥7 | ≥7 | 10–12 | 10–12 | 10–12 | | | | |
| Dissolved oxygen, mg/L3) | ≤0.1 | ≤0.1 | ≤0.05 | | | | | | | |
| Dissolved solids, mg/L | Without superheater: <4000, <3500, <3000 | With superheater: <3000, <2500 |
| SO2-3, mg/L | 10–30 | 10–30 | | | | | | | | |
| PO3-4, mg/L | 10–30 | 10–30 | | | | | | | | |
| Relative alkalinity, free NaOH/dissolved solids | <0.2 | <0.2 |
| Oil content, mg/L | ≤2 | ≤2 | ≤2 | | | | | | | |
| Iron content, mg/L6) | ≤0.3 | ≤0.3 | ≤0.3 | | | | | | | |
1) The basic unit for hardness in mmol/L is c(1/2Ca2+, 1/2Mg2+); the same applies hereinafter. 2) The basic units for alkalinity in mmol/L are c(OH-), 1/2CO3^2-, and HCO3-, the same applies hereafter. For boilers that have low requirements regarding steam quality and do not include a superheater, the upper limit for the alkalinity value can be appropriately increased, provided that the user obtains approval from the local boiler and pressure vessel safety supervision authority. 3) Deoxidization is required when the rated evaporation capacity of the boiler is 6 t/h or more. For boilers with a rated evaporation capacity of less than 6 t/h, deoxidization measures should be applied to the feedwater in case of local corrosion; the oxygen content in the feedwater supplied to turbines should be less than or equal to 0.05 mg/L. 4) If it is difficult to determine the dissolved solids, conductivity or chloride (Cl-) levels can be used as indirect indicators; however, the ratio between dissolved solids and conductivity, or between dissolved solids and chloride (Cl-), should be determined through experimentation. The ratio should also be rechecked and adjusted regularly. 5) The relative alkalinity of fully welded structure boilers can be left uncontrolled. 6) Only for fuel and gas boilers 2, as well as steam boilers and combined steam-water boilers with a rated evaporation capacity of 2 t/h or less and a rated steam pressure of 1.0 MPa or less (provided that there are no special requirements regarding the quality of steam and water), can in-boiler chemical treatment be employed. However, strict supervision must be exercised over scaling, corrosion, and water quality in the boiler; proper dosing, sludge removal, and cleaning procedures must be carried out, and the water quality must meet the requirements specified in the table below. Parameters: For water supply to boilers, the suspended solids level should be ≤20 mg/L; total hardness should be ≤4 mmol/l; total alkalinity should range from 8 to 26 mmol/l; the pH value at 25°C should be ≥7 and between 10 and 12. The dissolved solids level should be less than 5000 mg/L. For pressure-rated hot water boilers, external water treatment is required. For non-suspended pressure-rated hot water boilers with a rated power of 4.2 MW or less, as well as atmospheric-pressure hot water boilers, internal chemical treatment can be used; however, close monitoring of scaling, corrosion, and water quality is necessary, and proper chemical treatment must be carried out. The water quality must meet the specifications outlined in the table below. Items: In-boiler chemical treatment, External chemical treatment. Feed water, Boiler water, Feed water, Boiler water. Suspended solids, mg/L: ≤20, ≤5. Total hardness, mmol/L: ≤6, ≤0.6. pH (25°C): 1) ≥7, 10-12, ≥7. Dissolved oxygen, mg/L2): ≤0.1. Oil content, mg/L: ≤2, ≤2. 1) The pH value of the boiler water is controlled between 10 and 12 by adding chemicals. 2) The feed water for pressure hot water boilers with a rated power of 4.2 MW or more should be deoxygenated; the feed water for pressure hot water boilers with a rated power of less than 4.2 MW and atmospheric pressure hot water boilers should also be deoxygenated as much as possible. 4. For DC (through-flow) boiler feed water, external chemical treatment should be employed, and the water quality shall comply with the standards specified in Table 1 for a rated steam pressure of greater than 1.6 Mpa and less than or equal to 2.5 Mpa. 5. The water quality specifications for waste heat boilers and electric heating boilers shall meet the requirements of boilers of the same type and with the same parameters. 6. The water quality testing methods shall be carried out in accordance with Appendix A (the appendix to the standards). Common boiler water treatment equipment: boiler water softening equipment, fully automatic sodium ion exchangers
The standards for industrial boiler water quality upstairs are still those from version 01; currently, version 08 is in use. Please leave a message if you need it
Generally, the water quality standards for circulating cooling water, GB50050-95, are used. It should be GB50050-2007 now.