Ozone Solutions has recently added a new ozone generator to our product line. The NANO Ozone Generator is manufactured by Absolute Ozone and is perfectly suited for lab applications where high concentrations of ozone are required.
The NANO Ozone Generator can produce ozone concentrations greater than 9% by weight from oxygen at flow rates of less than 1 LPM. When lab tests are performed on a small scale it is imperative to have ozone generated at the concentrations possible. Ozone solubility is dependent upon ozone concentration, this makes high concentrations of ozone extremely beneficial in any application.
The NANO Ozone Generator can be used for small industrial applications where the small size will come in handy. With the great efficiency of this ozone generator very low oxygen flow rates will still produce great ozone outputs. At only 3 LPM of oxygen 15 g/hr of ozone is produced with the NANO Ozone Generator.
With easy to use controls and a small compact size the NANO Ozone Generator can be useful for many applications. The low price of the NANO Ozone Generator opens up an entire new world of possibilities for our customers on a budget who demand the highest ozone concentrations possible.
For even higher ozone concentrations we still offer the HC-30 Ozone Generator. The HC-30 is capable of 12-14% ozone concentrations at very low flow rates. The NANO Ozone Generator is manufactured by the same company and with the same technology as the HC-30 at a lower price.
Ozone is dissolved into water to create aqueous ozone for many applications. This page is a general overview of the methods and devices to dissolve ozone into water, along with a few helpful tips for the novice ozone user.
Ozone cannot be stored, therefore it must be generated on-site and dissolved into water on-site at the rate of consumption. Ozone is generated as a gas that must be dissolved into water. A mixing device will be necessary for ozone gas to dissolve into water efficiently. There are many variables to consider when determining the proper mixing device for a given application. The information provided below serves to provide a better understanding of the variables that may affect your application.
Bubble Diffusers
Bubble diffusion is the oldest and simplest method for dissolving ozone into water. This is essentially a porous device used for breaking the gas into small bubbles at the bottom of a water column to allow the bubbles to slowly rise to the top of the column and dissolve into water.
Pore Size
The pore size of the diffuser will affect the size of gas bubble that is created with the bubble diffuser. Two smaller bubbles will have greater surface area than one bubble of the same gas volume. Greater surface area will achieve improved contact with the gas bubble and water, therefore increasing the rate of mass transfer of ozone into water. It is important when choosing a bubble diffuser to find the smallest pore size possible.
Water Column Height
The height of the water column that ozone is bubbled into will affect the mass transfer efficiency greatly. The diffuser should be placed at the bottom of the column, this way the gas bubble must travel the greatest distance within the water column prior to escaping into the head space. Taller columns will lengthen the time duration that the bubble is in contact with the water and can dissolve into the water. More importantly, taller columns will create a higher pressure at the bottom of the column. This high pressure will exert greater force on the surface of the bubble and force more gas into solution.
Practical Application
Bubble diffusers can dissolve ozone into water efficiently; however, a fine pore diffuser must be used with a very tall water column. Water columns shorter than 10 feet typically achieve less than 50% mass transfer efficiency. Water columns 20 feet tall can achieve mass transfer efficiency up to 90%. This may not be practical in a given application. Fine pore diffusers can also plug with contaminates easier and cause poor long term performance. When designing a water treatment system using bubble diffuser keep safety in mind as high levels of un-dissolved ozone may escape from the head-space of the water.
Venturi Injector
A venturi injector is a very common method of ozone injection in industrial application. A venturi injector combines a method for ozone injection and provides good mass transfer efficiency in one device. A venturi injector requires a pressure differential across the device to create a vacuum to pull ozone gas into the device. Then, using mixing vanes the gas is thoroughly mixed with the water.
A venturi injector creates the very small bubbles desired for great mass transfer, and a violent mixing action to dissolve gas into water. Using a ventui injector alone may achieve mass transfer rates of 90%.
Water Pressures
For a Venturi Injector to work properly there must be a pressure differential between the inlet and outlet of the device. This usually requires a separate water pump to increase the water pressure at the inlet of the venturi injector. It is then important that the outlet of the venturi injector is not obstructed or impeded in any way.
We suggest placing pressure gauges directly at the inlet and outlet of the venturi injector. This will help with troubleshooting and determine the effectiveness of the device.
Off-gas System
Using a venturi injector will require a method of removing the un-dissolved oxygen and ozone from the water. Unlike the bubble diffuser where the bubbles will naturally rise to the head-space and escape the piping system used with a venturi injector has no method of removing this un-dissolved gas, one must be provided. A contact tank is a popular method, there are also de-gas chambers and columns that can be used. Ozone compatible air vents are used to remove this gas and vent to a safe location or to an ozone destruct unit.
If an off-gas system is not used the excess gas bubbles that may carry residual ozone can off-gas in undesirable locations causing safety concerns. Also, this excess gas may volatilize some of the dissolved ozone back into the gaseous form.
By-pass and plumbing
Venturi injectors become an integral part of the plumbing system in use. A pump is commonly placed prior to the injector, a tank after the injector. A by-pass loop is also commonly used to allow regulation of water flow through the injector and greater flexibility. Follow this link to the Mazzei website for some great examples of these plumbing options.
Venturi Injector Performance and sizing
Venturi injector sizing is a function of the water flow rate through the device. Water pressure will also play a factor in the determination of the venturi injector sizing. Each venturi injector is supplied with a performance chart illustrating the water flow, pressure, and gas suction provided by that venturi injector. Follow this link for extra guidance on this issue.
Water back-flow prevention
When using a venturi injector it is necessary to use a device to ensure water cannot flow from the venturi injector to the Ozone Generator. There are many devices used for this task: check valves, water traps, and shut-off valves are all used. We have found the best success using a quality water trap in conjunction with a check valve to prevent all water back-flow.
Diagram of system using a venturi injector, pump, contact tank, and air vent.
Static Mixer
Static mixers are any static device designed for the sole purpose of mixing two flows together. In our application we are mixing ozone gas with water, therefore the same principle of breaking the bubbles up into the smallest possible bubbles is the goal with the static mixer.
There are a variety of static mixers on the market, some go by trade names. For example Mazzei markets a static mixer under the name “Flash Reactor”. While there may be a variety of static mixers on the market they all serve the same function, dissolving ozone gas into water.
Sizing a static mixer
A static mixer is sized based on the velocity of water through the mixer. Each static mixer has vanes or mixing devices inside that require a specific velocity of water past those devices to achieve the desired results. This sizing will translate to water flow rate for our purposes. Each mixer should be sold and marketed with a range of flow rates that the mixer will work well with.
Ozone Injection
Ozone can be injected upstream of the static mixer using a tee or any other device to force ozone gas into the water stream. Then, the static mixer can be used to break up the gas into small fine bubbles to dissolve into water efficiently. Essentially a static mixer can be used in place of a venturi injector, this can be helpful when energy savings are desired due to the lack of necessary pressure differential.
To force ozone gas into the water stream the ozone gas must be at a higher pressure than the water stream. Usually a pressure of 10 PSI or greater is necessary to achieve gas flow into the water stream. This may eliminate the option of using only a static mixer and may require using a venturi injector to inject the ozone into water. The option of placing a static mixer in-line after the venturi is also an option.
Plumbing and piping
A static mixer can be placed anywhere in a piping system intended to mix ozone gas with water. The best location when using a venturi injector to infuse ozone with the water is a few feet downstream of the injector. If using a contact tank or off-gassing column place the static mixer directly at the inlet of the tank with the venturi a few feet (as far as practical) upstream from the static mixer.
Tips for dissolving ozone into water
Below are some helpful tips and guidelines to take into consideration when dissolving ozone into water.
Water Temperature
The solubility of ozone into water is temperature dependent. Lower water temperatures will achieve greater dissolved ozone levels due to a higher solubility rate. The solubility rate is the maximum ration of liquid to gas achievable for a given gas. While there are many other factors that will affect your mass transfer of ozone into water, it is very simple to understand that lower water temperatures increase solubility, if the solubility rate increases the mass transfer of ozone into water will increase.
Solubility of ozone gas
Temp deg C
Solubility
0
.64
5
.5
10
.39
15
.31
20
.24
25
.24
30
.15
35
.12
At atmospheric pressure
Water Pressure
Water pressure will play a role in the solubility of ozone into water. When ozone gas is injected into water at higher pressures more force will be placed on the wall of that gas bubble. This force will allow ozone to dissolve into water more efficiently. Any of the ozone injection methods will be more efficient when the entire system is operated at an elevated pressure. For example, water pressures of 35 PSI will have about twice the solubility as water pressures of 10 PSI.
Ozone Concentration
Ozone gas is normally measured in g/hr, however this is only a measurement of how much ozone is generated. Another method of measuring ozone is the concentration. More ozone in a given gas volume will mean that the gas has a higher concentration of ozone. This is normally measured in % by weight, or g/m3.
Ozone at higher concentrations will dissolve into water more efficiently than ozone at lower concentrations. See chart below for details.
Chart shows the saturation point of ozone in water based upon ozone concentration and temperature, at atmospheric pressure. Dissolved ozone level shown in mg/l
Water Quality
Any contaminate in the water that may affect water quality may also consume ozone, this will lower the dissolved ozone levels in the water. While this may be a desired effect due to the purpose of the ozone in water, it is important to take water quality into consideration when attempting to achieve a specific dissolved ozone level in the water.
A good example and often overlooked factor is chlorine in the water. Most city water supplies will have a chlorine residual in the water. When dissolving ozone into this water the ozone may react with the chlorine and consume some of the ozone.
Summary:
Dissolving ozone into water for any of the various applications listed above may be very simple, or could be extremely complicated. This will be depending upon the application, and the variables working within that application. This information should only serve to offer guidance on this process, for additional information refer to the great resources below, or contact our office and speak with one of our Application Engineers.
References:
Ozone in Drinking Water Treatment — Kerwin L. Rakness pg. 47 & 48
Ozone in Water Treatment Application and Engineering — cooperative research report — Bruno Langlais, David Reckhow, Deborah Brink: pg. 24-27, 139-142,
If you have been around an Ozone Systems for any length of time you have experienced it, the elusive ozone leak. Ozone leaks can be frustrating, ozone leaks can make for a bad day, ozone leaks can even bring an end to what would otherwise be a successful ozone project. This document is intended to provide some tips and advice on how to find those elusive ozone leaks.
Ozone piping and delivery systems used in continuous duty will eventually leak. It is a fact of life that cannot be ignored. The question is when, not if, the piping and fittings carrying ozone gas will leak. Understanding that leaks will happen is an important step to operating an Ozone System for the long term.
Ozone is regulated by OSHA as a gas that is potentially dangerous to human life. The specifics of these regulations are covered in other articles, however here the are basics:
0.3 ppm for no more than 15 minutes of exposure.
0.1 ppm for 8 hours per day of exposure doing light work.
0.08 ppm for 8 hours per day of exposure doing moderate work.
Ozone has a short half life. This means ozone will naturally break down into oxygen very quickly. In a normal room, at standard operating conditions, the half life of ozone averages 20-30 minutes. This may make it hard to find ozone leaks, especially if the leak is intermittent.
Ozone has a low vapor pressure, and therefore does not fill the room uniformly. If you could see ozone in a room it would look similar to smoke from a cigarette wafting carelessly through the room on its own terms. This may make unusually high ozone levels detectable in areas far from where the ozone is actually escaping.
Ozone tends to cling to rough surfaces such as fabrics. You will notice that long after ozone levels have been depleted in the area, your arms and shirt may still carry an ozone odor. This same phenomenon may occur near walls, carpet, and other surfaces.
Small ozone leaks can cause very high ambient ozone levels.Ozone gas at 10% by weight equals 68,800 ppm. Even in a large room with good ventilation it is easy to see how an ozone level above 0.1 ppm is achievable. Also, consider this example: 10% ozone gas leaking into a utility room 10′ x 10′ x 10′ (1000 cubic feet) at a flow rate of 0.01 LPM flow rate could achieve a 1.3 ppm ambient ozone level based on a typical ozone gas half life of 20 minutes. This is an extreme example; however, it is worth considering that it will be extremely difficult to find a leak as small as 0.01 LPM, yet it may cause unsafe ozone levels in your application. Consider your application and consider how small of an ozone leak could create ozone levels above the OSHA threshold of 0.1 ppm. You may be looking for a smaller leak than you think…
All fittings and connections. Threaded fittings are common leak points, as well as compression fittings using different material tubing and fittings are common leaks (example: Teflon tubing in Stainless compression fitting).
Tubing or piping that may be rubbing against something.
Valves or any moving part. Ball valves commonly leak from the handle area, needle valves commonly leak from the shaft.
Ozone Generator Corona cell.
Flow Meters can leak on tube seals and body.
Basically, anywhere ozone gas is plumbed. While ozone will typically not leak from long runs of Teflon or Stainless Steel tubing, rule nothing out. Start your search in the obvious places, and throw out and replace any non ozone resistant materials.
Tips on finding ozone leaks
Enough bad news, how do we find these elusive ozone leaks if and when they occur? That is the question we are asked almost every day. We have some great tips and suggestions below.
Remember, when looking for ozone leaks, you may have a short window of time before the ozone level you are exposed to rises above safe levels. Keep an ozone sensor with your, or leave the integrated ozone sensor in tact. When the ozone level is too high, get out! Take a break, come back in 20-30 minutes.
Below are some methods we use and the pros and cons of each.
Many Ozone Sensors do not respond to ozone immediately and have a delay. That simply will not work to find an ozone leak in real time. An Ozone Sensor that responds to ozone immediately is absolutely necessary. Also, some Ozone Sensors will require a warm-up period. Ensure your Ozone Monitor is warmed up and ready to detect ozone. Below you will find a few examples of Ozone Sensors that do work. These are by no means the only sensors available that could be used, they are just our recommendations.
The favorite Ozone Monitors for leak detection are the A-21ZX from Eco-Sensors, and the C-16 from Analytical Technologies Inc. (ATI).
The A-21ZX has a small sensor protruding from the top of the sensor that works great to get in smaller spaces. This sensor requires a warm-up period, but once it’s warmed up it will react very quickly to ozone. The A-21ZX is small and compact and comes with a carry case. This is a great sensor to use when space is an issue. This sensor charges off 12 VDC power, so it can be charged it in the car on the way to the job site.
Checking for ozone leaks with the C16
The C-16 has a long probe with a sample pump. The sample pump pulls ozone gas to the internal sensor in real time. This allows you to get anywhere and really pinpoint the exact leak location. The C-16 is larger, but has a durable carry case.
When using these sensors or any others; place it directly against the piping or fittings in question and move it SLOWLY along the piping until the reading goes up. Take your time and ensure that you have pinpointed the location, remember air flow may be causing an ozone leak from another location to fool you, make sure you rule this out. After you are certain you have found the leak, keep in mind this may still be the general location. Ozone is tricky that way, it tends to trick you and your Ozone Sensor. Visually inspect all tubing and fittings, attempt to repair the leak if it is an easy fix. If you are not certain you found the specific fitting you may have to revert to the soapy water trick (see below) to pinpoint the leak.
Soap and Water
Spray soapy water on all the questionable fittings, then stand back and look for fine bubbles to form from the leaky area.
The old soap and water trick is still a favorite method of finding ozone leaks. After years in this business and countless elusive ozone leaks, a spray bottle and dish soap are still a great help. Why is this so great you ask?
No special tools, you can get a spray bottle and dish soap at every department store, grocery store, etc in the world.
You can turn the Ozone Generator OFF! Now you are looking for an oxygen, or air leak. No more safety concerns.
This method works, it just plain works.
For this method you need any old spray bottle and some dish soap. Don’t get too picky on ratios or mixing, put a copious amount of dish soap in the bottom of your spray bottle and fill the rest with water. Shake well and get to work.
Spray ALL the piping and fittings with generous amounts of your newly created concoction. Then, sit back and wait for the bubbles. Leaks may show up right away or it might take up to a minute to show very small leaks. This method will find the smallest of leaks. Tiny bubbles are created around small leaks and larger leaks will create large bubbles.
This method will not find the largest of leaks. Large leaks will blow the water away and never create bubbles. If the leak is this large you may be able to hear it, feel it, or find it with an Ozone Sensor.
This method will not work work well on large piping (larger than 1/2″ OD). There is too much surface area to create bubbles from the leak. For those scenarios it is best to use an Ozone Sensor, or potassium iodide.
This rag turned a darker color when it was draped over the leaking connection
A Potassium Iodide Solution (2% KI) can be soaked on a white rag for chemical detection. In the presence of ozone the rag will turn brownish or red due to oxidation by ozone gas. This is a good method to pinpoint ozone leaks in large ozone gas piping, tubing, and fittings when soapy water will not be effective. This method will require some method of finding the general area of the ozone leak. An Ozone Sensor should be used to find the general area of the potential leak, then the chemical potassium iodide soaked rag can be laid over this connection to determine exactly what area of the rag changes color. This will pinpoint exactly where the leaky fitting is located.
Your Nose
Your nose is NOT an ozone sensor, or an ozone leak detector! So don’t use it, or trust it. If you have an ozone leak that you detected with your nose, good for you. Now, go get an ozone sensor and verify the ozone level, then get the proper tools and go find that ozone leak.
Hopefully this helps you. Whenever troubleshooting any system a little common sense and patience will go a long ways. Take your time, take a break if you need to, and find that leak. But when you do find that leak make sure you replace that faulty tubing/fitting/valve, etc so it does not happen again.
This analyzer is now sold, for other used ozone analyzers please contact our sales team to learn about our latest arrivals.
We just recently received an H1-S IN USA high concentration ozone analyzer. This is a good used analyzer that will measure ozone concentration in g/m3. We just recently checked this units calibration against a few others in our calibration lab and found it be be very accurate. If you are looking for a good used (low cost) high concentration ozone analyzer, check this unit out.
One of the many mysteries of ozone application and use is the common Mazzei Venturi Injector. At Ozone Solutions, we field many questions and try to help customers understand and correctly apply the use of these injectors.
Venturi Injectors
Venturi Injectors work by forcing water through a conical body which initiates a pressure differential between the inlet and outlet ports. This creates a vacuum inside the injector body, which initiates ozone suction through the suction port.
Ozone Solutions has started to create a series of short videos illustrating some of our products. These are informative, educational, and fun to watch. See below for our first two videos.
We have just started carrying a new line of UV Ozone Photometers. These are manufactured by Aeroqual a manufacturer of other gas sensors. Ozone Solutions has carried the full line of Aeroqual Ozone Monitors for many years and we are happy to add these new Ozone Photometers to the line up.
At this time we have added the UV-H and the S-960S to our website. As these are field tested and proven this model line is sure to grow over time.
UV-H Ozone Photometer
The UV-H Photometer is a full feature, full function bench mount ozone analyzer. The UV-H boasts a range of 0 – 200 ppm, has relay controls, on-board data logging, and a super cool display/interface. Check out all the features of the UV-H on the product website.
S-960S UV Ozone Photometer
The S-960S is a smaller wall mount UV Ozone Analyzer manufactured for the OEM markets. This Analyzer is available in multiple configurations. Shown is a version with a display. This unit is available with or without a display. There is also the option of control relays, and digital, or analog outputs. For more information on this analyzer check out our website HERE.
Ozone Solutions carries a full line of full featured ozone analyzers. For more products and information check out our full line of ozone analyzers.
Ozone has many applications. One of these applications is a biocide in cooling towers. Cooling towers recirculate the same water over and over again within a mostly closed loop system. This water must have chemical treatment to maintain clean water with no bacteria or algae growth. Ozone can replace traditional chemicals and offer a green solution to this application.
We have recently completed an installation of a 300 g/hr ozone generation system into a large cooling tower at an ethanol plant. The use of ozone will replace chlorine and bi-sulfate chemical additions. Using ozone will eliminate the need to transport, store, and purchase bulk chemicals.
The ozone system produces ozone from a 300 g/hr water cooled ozone generator. This will produce 300 g/hr of ozone from 40 LPM of oxygen at 9% by weight from oxygen. Oxygen is provided by an Air-Sep AS-D oxygen concentrator using compressed air to provide 40 LPM of oxygen feed gas for the ozone generator. The AS-D is fed with compressed air supplied by the customers current compressed air systems.
Ozone is injected directly into a water recirculation line using a custom ozone injection point. The picture below shows the ozone gas plumbed into this injection point. This injection point will diffuse the ozone into the pipe via micro bubbles. This pipe recirculates ~300 gpm of water, this water travels 150 yards then discharges into the cooling tower basin. This pipe distance allows the ozone to achieve excellent mass transfer efficiency.
Currently this ozone system is rented by the customer with the option to purchase at any time. This offers great flexibility for the customer, and cost savings over the previous chemical additions. For information on our ozone solutions for your application contact us today.
Last week I finished the installation of an Ozone System for room disinfection. The purpose of this Ozone System is to generate and control a high gaseous ozone level inside of 10 rooms for disinfection purposes. Using ozone in the gaseous form is always tricky due to safety concerns. Also, ozone gas is very unstable, and can cause difficulty measuring the ozone, and keeping it away from unwanted areas.
This Ozone System uses an Air Sep Oxygen Concentrator to provide oxygen, and two TG-40 Ozone Generators produce 100 g/hr of ozone for this application. A large control box is used to regulate ozone levels and distribute this ozone to 10 separate rooms. A timer is used to allow the user to control the time that ozone is delivered to the rooms, this ensures no personnel are within the area during operation. Ozone Monitors are used to measure ozone in each of the rooms. User settable relays integrated into the Ozone Monitors allow the user to set ozone levels, solenoid valves will then open and close based on these settings to start and stop ozone flow to each room. Flow meters are installed to ensure adequate ozone flow, and to regulate ozone flow to each of the 10 rooms. This allows the user to deliver more ozone to one room than another. A data logger is also used to log all ozone levels. This data logger is equipped with an Ethernet connections allowing the users to see the ozone levels real time from any location from their personal computer.
To measure and control ozone, ten ES-600 ozone meters are used. This is a cost effective and reliable Ozone Monitor for these applications. This was chosen due to the functions included on this monitor, and the long term sensor costs. This Ozone Monitor uses a 0.1 ppm safety relay that cannot be changed. This allows a safety relay to be integrated that will set a safety light to alert personnel that ozone levels are above the 0.1 ppm level. A second relay is used to allow the user to set ozone levels from 0-20 ppm. This relay is set with simple push buttons accessed by easily removing the cover.
Long term costs of this Ozone Monitor are also low. No calibration is ever necessary of the ozone sensor, and the sensors never need to be sent back to Ozone Solutions. The entire sensor is replaceable with a pre-calibrated sensor. When the new pre-calibrated sensor module is installed, the old sensor is disposed of. As the pre-calibrated sensor module carries a cost of $150, this is a very low cost Ozone Monitor to maintain over the long term.
This first video is a typical ceramic bubble diffuser. This is a 80 micron diffuser. The gas flow is altered from very low, 1 LPM to a max flow of 10 LPM. This shows that the ceramic diffuser creates very small bubble size at low flow rates, however the bubble size increases as the flow rate increases. This shows the importance of using these diffusers only within the rated flow rates.
This second video is of the porous PTFE tubing bubbling ozone into water. This tubing creates bubbles about 100 micron in size. While PTFE tubing will have a long life, and will prevent any buildup or contamination to the diffuser over time, it does create the largest bubbles of the diffusers in our test.
This last video is of a stainless diffuser with a 20 micron rating. This video shows a range of flow from 20 SCFH, to 180 SCFH (3 CFM). This clearly shows that the smaller micron rating creates much smaller ozone bubbles in the water.
While all these diffusers have pro’s and con’s these video’s give a very informative visual as to the operation of these differs in water. We hope this information helps you make decision on the best possible diffuser for your application.
Read the First Comment 
If you have been around an Ozone Systems for any length of time you have experienced it, the elusive ozone leak. Ozone leaks can be frustrating, ozone leaks can make for a bad day, ozone leaks can even bring an end to what would otherwise be a successful ozone project. This document is intended to provide some tips and advice on how to find those elusive ozone leaks.
Checking for ozone leaks with the A-21ZX
Checking for ozone leaks with the C16
Spray soapy water on all the questionable fittings, then stand back and look for fine bubbles to form from the leaky area.
This rag turned a darker color when it was draped over the leaking connection
