Units of ozone concentration are usually expressed in two ways: mass concentration and volume concentration. Common ozone concentration units include milligrams per litre (mg/L), micrograms per litre (μg/L), milligrams per cubic metre (mg/m³) and volume percentage (%). The conversion relationship between these units is as follows:
• In the air:
• Mass concentration: 1 mg/m³ = 10^3 μg/m³
• Volume concentration: 1 ppm (parts per million) = 2.14 mg/m³
• In the water:
• Mass concentration: 1 mg/L = 1 g/m³ = 1 μg/mL
• Volume concentration: 1 ppm (parts per million) = 1 mg/L
Ozone purity refers to the ratio of ozone molecules in ozone gas to the volume or mass of the total gas. For example, if an ozone gas sample contains 95% ozone and 5% of other gases (such as oxygen), then the ozone purity of this sample is 95%.
The ozone purity generated by the ozone generator can vary according to the type and design of the equipment. Generally speaking, industrial-grade ozone generators can produce 60%-90% of ozone purity. Laboratory-level ozone generators can even produce ozone of higher purity, but these devices are usually used for research and specific applications.
