Industrial Ozone Generator Buying Guide: Sizing and Specs

Buying an industrial ozone generator comes down to four decisions: how many grams of ozone per hour you need, whether the machine runs on dried air or oxygen, how it is cooled, and how the ozone gets into your water or air. Get those right and the rest of the specification sheet falls into place. This guide walks through each decision in plain terms, using design figures published by the U.S. Environmental Protection Agency (EPA), so you can compare quotes with confidence.

An industrial ozone generator is a machine that produces ozone gas (O₃) on site, usually by corona discharge, at outputs measured in grams per hour (g/h) or kilograms per hour, for continuous use in water treatment, wastewater, food processing or odor control. Because ozone is unstable and breaks back down to oxygen, it cannot be bought in a cylinder; it must be generated where it is used.

How an industrial ozone generator works

Almost every industrial unit uses corona discharge. According to the EPA Alternative Disinfectants and Oxidants Guidance Manual, corona discharge “predominates in the ozone generation industry”: an oxygen-containing gas passes between two electrodes separated by a dielectric, and the electrical discharge splits oxygen molecules so the free atoms recombine as ozone. The EPA ozone disinfection fact sheet notes that most wastewater plants generate ozone by applying a high-voltage alternating current of 6 to 20 kilovolts across the discharge gap.

A complete system has four parts, and you should price all four, not just the generator:

• Gas feed system: supplies clean, dry air or oxygen.
• Ozone generator: the discharge cells, power supply and cooling.
• Contactor: the injector, diffuser or mixer that transfers ozone into the water, plus the tank that gives it contact time.
• Off-gas destruction: a unit that converts leftover ozone back to oxygen before venting.

Step 1: Size the output in grams per hour

Output is the single most important number. For water, the basic arithmetic is simple: required ozone (g/h) equals flow (m³/h) multiplied by the ozone dose (mg/L, which is the same as g/m³). A line treating 10 m³/h at a dose of 2 mg/L needs 20 g/h actually dissolved in the water.

Then allow for transfer losses. Not all the gas dissolves, and the EPA manual states that transfer efficiencies “of greater than 80 percent typically are required for efficient ozone disinfection.” If your contactor transfers 80 percent, the generator in the example above should deliver about 25 g/h. Add headroom so the machine does not run flat out every hour of the day.

The hard part is choosing the dose. It depends on what the water contains, because organic matter, iron, manganese and sulfides all consume ozone before any measurable residual appears. The EPA fact sheet is blunt about this: it is “critical that all ozone disinfection systems be pilot tested and calibrated prior to installation.” HSVN takes the same approach for wastewater: its engineers test a sample of the customer’s water before confirming capacity, according to the industrial ozone generators page from HSVN.

Air treatment is sized differently

For deodorizing exhaust air or treating empty rooms, output is matched to air volume and odor load rather than to a water dose. Never size an air application on the assumption that people can stay in the space; occupational limits are discussed in Step 6.

Step 2: Choose the feed gas, air or oxygen

The feed gas sets the ozone concentration the generator can reach. The EPA manual gives a maximum of about 3 to 5 percent ozone by weight from air, versus 8 to 14 percent from high-purity oxygen, and notes that oxygen “approximately doubles ozone concentration for same generator.”

Feed gas	Typical ozone concentration (EPA)	Advantages	Trade-offs
Dried air	Up to about 3-5% by weight	Proven, simple, suits small and large systems	More energy per kg of ozone; needs compressor, filters and desiccant dryer
Oxygen from a PSA concentrator	About 8-14% by weight	Higher concentration, better transfer into water	Oxygen-compatible materials, more equipment to maintain

On-site oxygen is usually made by pressure swing adsorption (PSA), which the EPA manual describes as producing an oxygen-rich feed of 80 to 95 percent O₂. Whichever gas you use, it must be dry: the EPA specifies a maximum dew point of -60°C. Moist gas reacts in the discharge cell to form nitric acid, which corrodes the generator and lowers output.

Concentration matters most when you dissolve ozone with a venturi injector. The EPA manual says injector systems work best with ozone gas concentrations greater than 6 percent by weight, which in practice points to oxygen feed for water treatment.

Dr.Ozone builds both types. According to HSVN, the small D series (1 to 5 g/h) runs on ambient air at 1 to 5 g/m³, while the D-S series from the D-30S upward integrates a PSA oxygen unit and air compressor and reaches 80 to 120 g/m³. For example, the Dr.Ozone D-50S industrial ozone generator is listed at 50 g/h with a 10 L/min oxygen supply at 92% ± 3%. Where an existing generator needs a separate oxygen source, HSVN also supplies Dr.Oxy industrial oxygen generators from HSVN.

Step 3: Check the cooling method

Ozone generation is inefficient, and heat is the enemy of output. The EPA manual states that about 85 percent of the electrical energy fed into an ozone generator is lost as heat, and that adequate cooling is needed to keep the generator efficient. The fact sheet lists three cooling options: air, water, or water plus oil.

• Air (fan) cooling suits small parallel-plate generators.
• Water cooling is standard on larger units. Ask for the required cooling water flow, pressure and inlet temperature, and confirm your site can supply them year round.

As an example of what to look for on a datasheet, the Dr.Ozone D-50S lists fan and water cooling, a cooling water flow above 0.3 m³/h and an inlet water temperature of 20 to 25°C.

Step 4: Plan how ozone reaches the water

A generator is only as good as its contactor. The EPA manual describes three common dissolution methods:

• Bubble diffusers: no moving parts and 85 to 95 percent transfer efficiency, but they need deep basins of roughly 18 to 22 ft, and pores can clog when iron and manganese are being oxidized.
• Venturi injectors: very effective transfer and shallower tanks, at the cost of extra pumping energy.
• Turbine mixers: transfer above 90 percent, but they use 2.2 to 2.7 kWh per lb of ozone transferred.

Injectors and mixers usually need a downstream contact tank to deliver enough contact time. Ask your supplier to show the full flow diagram, not only the generator.

Step 5: Look at controls, materials and energy

Controls. Small systems can run on a manual output knob and timer. Larger or unattended systems benefit from automatic control. The EPA manual recommends a dew point detector on the feed gas, flow switches on cooling water, a pressure switch, and ozone detectors interlocked to shut the generator down. HSVN lists its D-Pro line with PLC control and a 7-inch touch screen; see the Dr.Ozone D-Pro premium ozone generators at HSVN or the Dr.Ozone D-100 Pro with PLC control (100 g/h, 2.6 kW).

Materials. Ozone is highly corrosive, so every wetted part must resist it. The EPA manual recommends 304 stainless steel for dry ozone gas, 316 stainless steel for wet service such as contactors and off-gas piping, and Teflon or Hypalon for gaskets.

Energy. The EPA manual puts ozone generation at 8 to 17 kWh per kg of ozone. Use the rated power on each quote to compare running costs on an equal footing.

Step 6: Budget for safety and maintenance

Ozone is toxic, and both the U.S. Occupational Safety and Health Administration (OSHA) and the National Institute for Occupational Safety and Health (NIOSH) set workplace limits of 0.1 ppm, as listed in the NIOSH Pocket Guide entry for ozone. That makes an off-gas destruct unit and an ambient ozone monitor part of the purchase, not optional extras.

For maintenance, the EPA manual advises cleaning dielectric tubes when generator efficiency drops 10 to 15 percent, changing air filters and desiccant periodically, and purging the generator with dry gas after a shutdown before energizing it. Ask who will do this work locally and how fast spare parts arrive. Dr.Ozone describes its local support in its ozone generator maintenance and repair service.

Buyer’s checklist

• Rated output in g/h, at what feed gas and concentration?
• Can output be turned down, and over what range?
• Feed gas preparation included: compressor, dryer, PSA oxygen unit?
• Cooling method and the cooling water the site must provide.
• Contactor and contact tank design, with expected transfer efficiency.
• Off-gas destruct unit and ambient ozone monitor with shutdown interlock.
• Wetted materials: 304 or 316 stainless steel, PTFE tubing and seals.
• Warranty terms, spare parts and local service.

Frequently asked questions

How many g/h of ozone do I need?

Multiply your water flow in m³/h by the ozone dose in mg/L to get grams per hour actually dissolved, then divide by the expected transfer efficiency of your contactor. The dose itself depends on the water’s ozone demand, so a bench or pilot test on your own water is the reliable way to fix it before buying.

Is an oxygen-fed ozone generator better than an air-fed one?

Oxygen feed roughly doubles the ozone concentration from the same generator, according to EPA, which improves transfer into water and suits venturi injection. Air feed is simpler and works well for small outputs and air treatment. The right choice depends on your output, budget and how the ozone will be dissolved.

Why do industrial ozone generators need water cooling?

EPA estimates that about 85 percent of the electricity an ozone generator uses becomes heat, and higher temperatures reduce ozone output. Small units can shed that heat with fans, but larger generators normally use a cooling water circuit to hold the discharge cells at a stable temperature and keep production efficient.

Do I need an ozone destruct unit?

Yes, for any contact tank that vents gas. Off-gas leaving a contactor still carries ozone far above the 0.1 ppm workplace limit set by OSHA and NIOSH. A thermal or catalytic destruct unit converts it back to oxygen before release, and an ambient monitor confirms that the room stays safe.

Ready to size a system? Send your flow rate, water or air analysis and target result to the Dr.Ozone team through our contact page, or browse the full range of industrial ozone generators from HSVN, the Vietnamese manufacturer behind Dr.Ozone.