The norms for boiler water quality, the required mode for its corrective treatment, and the modes for continuous and periodic blow-off are determined based on the manufacturer's instructions, typical instructions for maintaining water chemistry, other departmental regulations, or thermal-chemical testing.
The norms for feedwater quality are adopted based on the boiler’s instructions or DNAS 0.00-1.08-94 "Rules for the Construction and Safe Operation of Steam and Hot Water Boilers."
Main requirements for water quality in hot water systems
With a heating temperature up to 100 °C
| Total Heating Power (kW) | Total Hardness (mmol/l) |
|---|---|
| Up to 50 | Not regulated |
| 50–200 | Not more than 2.0 |
| 200–600 | Not more than 1.5 |
| Over 600 | Less than 0.02 |
With a heating temperature above 100 °C
| Quality Indicators | Demineralized Water | Softened Water |
|---|---|---|
| Electrical Conductivity at 25 °C (μS/cm) | 10–30 | 30–100 |
| pH at 25 °C | 9–10 | 9–10.5 |
| Oxygen Content (mg/l) | Less than 0.1 | Less than 0.05 |
| Total Hardness (mmol/l) | Less than 0.02 | Less than 0.02 |
Main requirements for quality of nutrient water used in industrial energy systems
Nutrient water for heating systems
| Indicator | Heating System (Open) | Heating System (Closed) | ||||
|---|---|---|---|---|---|---|
| Network Water Temperature (°C) | 115 | 250 | 200 | 115 | 250 | 200 |
| Transparency (cm, minimum) | 40 | 40 | 40 | 30 | 30 | 30 |
| Carbonate Hardness (μg-equiv/kg) at pH no more than 1 | 800 / 700 | 750 / 600 | 375 / 300 | 800 / 700 | 750 / 600 | 375 / 300 |
| At pH 8.5 | Not allowed | Calculated according to OST 108.030.47081 | ||||
| Dissolved Oxygen Content (μg/kg) | 50 | 30 | 20 | 50 | 30 | 20 |
| Iron Compounds Content (μg/kg) | 300 | 300/250 | 250/200 | 600/500 | 500/400 | 375/300 |
| pH Value at 25°C | From 7.0 to 8.5 | From 7.0 to 11.0 | ||||
| Oil Products Content (μg/kg) | 1.0 | |||||
Steam water tube boilers
| Indicator | Boilers working on liquid fuel | Boilers working on another type of fuel |
|---|---|---|
| Transparency (cm, minimum) | 40 | 20 |
| Total Hardness (μg-equiv/kg) | 30 | 100 |
| Dissolved Oxygen Content (μg/kg) | 50 | 100 |
Steam and energy-technological boilers and waste heat boilers
| Indicator | Operating Pressure, MPa (atm) | 0.9 (9) | 1.4 (14) | 1.8 (18) | 4 (40) | 5 (50) |
|---|---|---|---|---|---|---|
| Gas Temperature, °C | ≤ 1200 | ≤ 1200 | >1200 | ≤ 1200 | >1200 | |
| Transparency by font, cm, not less than | 30 / 20 | 40 / 30 | 40 | |||
| Total hardness, µg-eq/kg | 40 / 70 | 20 / 50 | 15 | 10 | 5 | |
| Content, µg/kg | ||||||
| Iron compounds | Not regulated | 150 | 100 | 50 | ||
| Dissolved oxygen for boilers: | With cast iron economizer | 150 | 100 | 50 | 50 | 30 |
| With steel economizer | 50 | 30 | 30 | 30 | 20 | |
| pH value at 25 °C | Not less than 8.5 | |||||
| Petroleum products content, µg/kg | 5 | 3 | 2 | 1 | 0.3 |
This table summarizes the key parameters and requirements for various water quality levels for different types of boilers and heating systems. For further calculations, specific instructions provided by relevant standards and regulations should be followed.
