The dosing formula
The polyphosphate dose is obtained by passing water through a mass of crystals according to the following formula:
C = Q × D / V
- C = mass of salts in kg
- Q = water flow rate to be treated in m³/h
- D = required polyphosphate dosage in g/m³
- V = dissolution speed of the salts in g/kg/h
Flow / quantity table (standard conditions)
As a guideline, the polyphosphate quantity required according to flow rate, under standard conditions:
| Flow rate (l/h) | Polyphosphate quantity (kg) |
|---|---|
| 100 | 1 |
| 200 | 2 |
| 300 | 3 |
| 400 | 4 |
| 500 | 5 |
| 600 | 6 |
| 700 | 7 |
| 800 | 8 |
| 900 | 9 |
| 1000 | 10 |
Standard conditions: pH 7.0 — hardness 20°F — temperature 17.5°C — grain size 12/25 mm.
Factors that influence dosing
The dissolution speed depends on pH, temperature and grain size. The lower the pH and temperature, the slower the dissolution. A grain size below 6/10 mm dissolves about twice as fast as a 10/20 mm grain size. Dosing must therefore always be defined according to these real parameters.
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