# Ozone 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: 1000 kg/m3

USEFUL CONVERSION FACTORS (for water)

• 1000 liters = 1 m3 = 264 US gallons
• 1 gal = 3.785 liters = 3785 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 = 7284 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 = 6520 ppm ozone DETERMINING OZONE DOSAGE IN WATER

• Water Flow Rate x Ozone Dosage = Required Ozone Production

UNITS CONSISTENCY IS VERY IMPORTANT

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

• Flow rate (gpm) x 3.75 l/gal x 60 min/hr x ozone dosage (mg/l) = ozone production (mg/hr)

Let's 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 = 9084 mg/hr ( gm/hr)

Remember that 9 mg/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

• Flow rate (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 m3/1000 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 / 100 g/m3 x 6.99 wt % = 9.8 wt %

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