Recommended Water Quality For Firetube Boilers
Feed Water | |
| pH | 8.5–9.2 – Should be alkaline at all times. |
| Hardness | Zero ppm |
| Silica | Dictated by blowdown and maximum boiler residuals. |
| Total Dissolved Solids (TDS) | Dictated by blowdown and maximum boiler residuals. |
| Dissolved Oxygen | Should be reduced to less than 0.005 cc/l by mechanical deaeration and the residual controlled by addition of a suitable oxygen scavenger – normally sodium sulfite. |
| Suspended Matter | Zero |
| Oil and Grease | Zero |
Boiler Water | |
| pH | 10.5-11.5 |
| Alkalinity (m) | 700 ppm (max.) |
| Total Dissolved Solids (TDS) | Boilers sized 20,000 pph or less – 3500 ppm (max.). Boiler sized larger than 20,000 pph – 2500 ppm (max.) |
| Phosphate Residual | 50 ppm as PO4 (min.) |
| Dissolved Oxygen | Zero. If sodium sulfite is used for oxygen scavenging, maintain 25-50 ppm as Na2SO3. |
| Suspended Matter | 50 ppm (max.) |
| Oil and Grease | 125 ppm (max.) |
This information is supplied as general guidance only and does not absolve the boiler owner from the responsibility of determining and maintaining water standards appropriate to the specific local water chemistry and specific boiler use.
