Ozone Conversions & Equations

Physical Properties, Standard conditions P = 101325 Pa, T = 273.3 K

• Density of ozone: 2.14 kg/m³
• Molecular weight of ozone: 48
• Density of oxygen: 1.43 kg/m³
• Molecular weight of oxygen: 32
• Density of air: 1.29 kg/m³
• Density of water: 1,000 kg/m³

Useful Conversion Factors: (for water)

• 1,000 liters = 1 m³ = 264 US gallons
• 1 gal = 3.785 liters = 3,785 ml
• 1 m³= 35.3 ft³ = 264 US Gallons

Ozone Concentration in Water

• 1 mg/l = 1 PPM O₃ = 1 g O₃/m³ water {By weight}

Ozone Concentration in Air By Volume

• 1 g O₃ / m³ = 467 PPM O₃
• 1 PPM O₃ = 2.14 mg O₃/m³
• 100 pphm (parts per hundred million) = 1 ppm (parts per million)

Ozone Concentration in Air by Weight

• 100 g O₃/m³ = 7.8% O₃ (Approximate)
• 1% O₃ = 12.8 g O₃/m³ (Approximate)
• 1% O₃ = 7,284 PPM Ozone

Ozone Concentration in Oxygen by Weight

• 100 g O₃/m³ = 6.99% O₃ (Approximate)
• 1% O₃ = 14.3 g O₃/m³ (Approximate)
• 1% O₃ = 6,520 PPM Ozone

Determining Ozone Dosage in Water

The formula is actually very simple. 

It is water flowrate x ozone dosage = required ozone production 

UNITS CONSISTENCY IS VERY IMPORTANT

Below is the formula for determining ozone generation requirements if you know common water and ozone parameters (namely flowrate in GPM and ozone dosage in mg/l).

• flowrate (GPM) x 3.75 l/gal x 60 min/hr x ozone dosage (mg/l) = ozone production (mg/hr)

Lets work through an example. How much ozone production is needed to dose 2 PPM into 20 GPM of water? (we will be using PPM throughout the rest of this example knowing that 1 mg/l = 1 PPM)

20 GPM x 3.75 l/gal x 60 min/hr x 2 PPM = 9,084 mg/hr (9 gm/hr)

Remember that 9 gm/hr will permit you to dose the water with 2 PPM of ozone. This does not mean that 2 PPM will be your final dissolved ozone concentration. Due to efficiency losses with injecting ozone and ozone demand of the water, your dissolved ozone concentration will be less.

Determine the output of an ozone generator

the formula is flowrate (lpm) x ozone concentration (g/m³) = ozone production (mg/hr)

Let’s work through an example: The ozone concentration exiting an ozone generator is 120 g/m³ at 5 lpm of oxygen flow. What is the output?

5 l/min x 120 g/m³ x (1 m³/1,000 l) = 0.60 g/min

g/min are not normal units in the ozone industry so we simply convert minutes to hours to get g/hr: 0.60 g/min x 60 min/hr = 36 g/hr

Sample Conversions

Convert 140 g/m³ to wt% (oxygen feedgas).

based on the conversion above, 100 g/m³ = 6.99 wt. %

therefore 140 g/m³ / 100 g/m³ x 6.99 wt. % = 9.8 wt.%