| Drum peessure, psig | Total dissolved solidsb in boiler water, ppm (max.) | Total Alkalinityc in boiler water, ppm | Suspended solids in boiler water, ppm (max.) | Total dissolved solidsc,e in steam, ppm (max. expected value) | |
| Drum-type boilers | 0-300 | 700-3500 | 140-700 | 15 | 0.2-1.0 |
| 301-450 | 600-3000 | 120-600 | 10 | 0.2-1.0 | |
| 451-600 | 500-2500 | 100-500 | 8 | 0.2-1.0 | |
| 601-750 | 200-2000 | 40-400 | 3 | 0.1-0.5 | |
| 751-900 | 150-1500 | 30-300 | 2 | 0.1-0.5 | |
| 901-1000 | 125-1250 | 25-250 | 1 | 0.1-0.5 | |
| 1001-1800 | 100 | variabled | 1 | 0.1 | |
| 1801-2350 | 50 | variabled | N/A | 0.1 | |
| 2351-2600 | 25 | variabled | N/A | 0.05 | |
| 2601-2900 | 15 | variabled | N/A | 0.05 | |
| Once-through boilers | 1400 & above | 0.05 | N/A | N/A | 0.05 |
a Reprinted (with permission) from "Boiler Water Limits and Steam Purity Recommendations for Watertube Boilers," American Boiler Manufacturers Association, 1982.
b Actual values within the range reflect the TDS in the feedwater. Higher values are for high solids; lower values are for low solids in the feedwater.
c Actual values within the range are directly proportional to the actual value of TDS of boiler water. Higher values are for high solids; lower values are for low solids in the boiler water.
d Dictated by boiler water treatment.
e These values are exclusive of silica.