4,055 ppm = 4.075 PSU
| ppm | PSU |
|---|---|
| 4,040 ppm | 4.06 |
| 4,045 ppm | 4.065 |
| 4,050 ppm | 4.07 |
| 4,055 ppm | 4.075 |
| 4,060 ppm | 4.08 |
| 4,065 ppm | 4.085 |
| 4,070 ppm | 4.09 |
4055 ppm = 4.075 PSU
1 g/kg ≈ 1.0049 PSU · 1 mg/L ≈ 0.001 PSU · 1 ppm ≈ 0.001 PSU (dilute aqueous approximation)