664.5 g/kg = 667.756 PSU
| g/kg | PSU |
|---|---|
| 649.5 g/kg | 652.683 |
| 654.5 g/kg | 657.707 |
| 659.5 g/kg | 662.732 |
| 664.5 | 667.756 |
| 669.5 g/kg | 672.781 |
| 674.5 g/kg | 677.805 |
| 679.5 g/kg | 682.83 |
664.5 g/kg = 667.756 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)