420.5 g/kg = 422.56 PSU
| g/kg | PSU |
|---|---|
| 405.5 g/kg | 407.487 |
| 410.5 g/kg | 412.511 |
| 415.5 g/kg | 417.536 |
| 420.5 | 422.56 |
| 425.5 g/kg | 427.585 |
| 430.5 g/kg | 432.609 |
| 435.5 g/kg | 437.634 |
420.5 g/kg = 422.56 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)