Making Sense of Ozone Measurements

How much ozone is a particular machine making?

How concentrated is the ozone?

CONCENTRATION

One useful way to measure ozone concentration is to state how many parts of ozone are present per million parts of gas (normally air.) We can smell ozone when it is present in the air in as low as .01 parts per million (10 parts per billion). At .1 ppm levels in ambient air, ozone becomes uncomfortable. Industrial ozone generators can produce ozone in concentrations well over 100,000 parts per million. Usually these larger concentrations are expressed in % by weight. 100,000 ppm could be written as 100,000/1,000,000 which is 10/100 or 10%. Because the weight of an ozone molecule is heavier than the other gas molecules making up air, the actual measurement is 13.7 %wt. Parts per million is useful for many applications, but sometimes it is handy to use parts per billion for very low concentrations. The general principle is to reduce the number of zeros when communicating this information. We do the same thing when measuring distance with millimeters or kilometers etc. A good starting point to get a feel for ozone concentration is to become familiar with ppm and %wt. We provide definitions for other common units and links for conversions and calculators at our calculations page.

QUANTITY

A second dimension of ozone measurement is the actual quantity of ozone being produced or used. The production of smaller generators is measured in grams per hour. The production of the largest generators is measured in pounds per day. 1 lb/day ozone = 18.89 g/hr ozone. The smallest ozone generators we sell generate less than a half of a gram per hour. That would be about a hundredth of a pound per day which is an awkward figure to use. “Grams per hour” happens to be practical for describing the output of lower production machines. The larger ones we sell generate 1000 grams per hour or 50 pounds per day. Pounds per day happens to be practical for larger machines. A drinking water treatment plant in Texas uses up to 42,900 pounds of ozone per day (over 200 tons). One lightning storm can generate over 200 tons of ozone.

FLOW RATE

A third dimension of measurement for any gas application is flow rate. When generating ozone, flow rate will affect the ozone concentration. With a given ozone production rate (for example, 200 grams per hour), lower flow rates will result in higher ozone concentrations. Higher flow rates will result in lower concentrations. One useful calculator helps determine the amount of ozone needed to supply a particular concentration at a particular flow rate.  For example, if you need a concentration of 5% by weight and have an oxygen flow of 10 LPM, you will need a generator capable of 43 grams per hour. If the flow doubles to 20 LPM, the concentration is cut in half.

People working with municipal water treatment get used to working with larger units such as pounds per day and high ozone concentrations. People working with sanitation equipment and other mid-scale applications get used to thinking in terms of grams per hour and the whole spectrum of ozone concentration measurements. Those involved in small household applications and generators are more familiar with milligrams per hour and low concentrations. Our system integration experts need to be familiar with the whole spectrum of measurements. Familiarity and precision in application grows with years and diversity of experience. Our online calculator provides a powerful tool for an efficient and effective integration of ozone into your application.

Oxidation Technologies provides equipment, engineering expertise, and service to a wide range of applications and ozone demands. Our service requires flexibility in thinking and a familiarity with the full spectrum of ozone concentrations. We build ozone systems to integrate into your existing industrial process. Every situation has a multitude of variables that will affect the performance.

Give us a call. We’d love to help you harness the power of ozone for your application.  515-635-5854

The Power of Ozone

Is there a way to see ozone at work? Check this out.

Ozone Destroying Colorant.

During some recent lab testing I had some high concentration dissolved ozone solution to play with. It was easy to see a 50 ppm ozone solution rapidly destroying color molecules in water. Ozone breaks apart bacterial, viruses and other water contaminants like it breaks apart the color molecules. Here at Oxidation Technologies we do a variety of product exposure testing with ozone. We are always happy to talk to you about harnessing the power of ozone for your application. Give us a call at  515-635-5854. Check out our website for fast and easy source of all ozone related supplies.

Clean Dry Air

Water content needs to be nearly zero for ozone generator feed gas.

Long term, reliable operation of an ozone system depends largely on clean, dry air. Unless you have liquid oxygen (LOX) as an oxygen source, your ozone will be generated from the oxygen found in ambient air. The air around us contains dust particles, and lots of water vapor. One cubic meter of air on a hot humid day can contain up to 30 grams of water. Even a gram of water vapor in a cubic meter of air (dew point -5 deg. F) will inevitably lead to failure of the ozone generating equipment. We need to get another 9/10 of a gram of water out to keep an ozone generator in good shape.

Water content in air is most commonly measured in terms of dew point. Dew point is the temperature at which water vapor condenses into liquid. When a mass of air cools down to very cold temperatures before water condenses, it indicates that there is not much water vapor in the air. The graph shows that dew point is not linear in relation to the amount of water vapor in the air. It is easy to see that the water content gets close to zero at about -50 degrees F. Large ozone systems operate with feed gas between -100 and -60.

An air filter and desiccant air dryer is often used to clean and dry the air for a small air-fed ozone system. The desiccant material absorbs moisture from the air as it passes through. When the desiccant becomes saturated, air flow is switched to a second chamber of desiccant material while heat is applied to the first to drive the water from the material in the first chamber. The processes switches back and forth, effectively dries the air to a dewpoint of -40 deg F. This is a cost effective level of dryness for small ozone systems.

Ozone systems that use an oxygen concentrator are able to take even more water out of the feed gas. The first line of defense will be the air filter for the air coming into the air compressor used for your ozone system. This filter will remove particles of dust that eventually wear out the compressor as well. The compression process also serves to remove much of the water when the hot compressed air cools forming water droplets that can be removed with a coalescing filter. A compressor with a means to cool the compressed air can bring the dew point from 60 to 40 degrees. This compressed air is forced through the zeolite sieve beds of and oxygen concentrator. The zeolite quickly absorbs the Nitrogen and remaining water vapor. As the oxygen concentrator cycles, the Nitrogen and water vapor is exhausted, leaving 93% oxygen with a dew point from -60 to -100 degrees F.  The oxygen concentrator works well as long as water vapor does not build up or condense in the sieve beds. They will not work well when the compressed air has a dew point above 40 degrees or the sieve material absorbs moisture during down time.

Oxidation Technologies provides sales, service, and system design of gas preparation equipment for ozone systems.  

Reduce Lift Station and Vent Odor Problems with Ozone

Lift station using ozone for pre-treatment and odor control

Ozone injected directly into the sewer pipe in the lift station controls vent odor problems, reduces monthly chemical costs, and pre-treats sewage coming into the treatment plant. I recently visited one of our sites using ozone for lift station and vent odor control, and then spent some time doing research to learn more about this application. The first thing I began to realize is how complex water and sewage treatment is. Treatment operators face a multitude of variables and different products and approaches to cleaning up water. A successful solution depends on a careful study of the particular situation and close observation of results. Solutions to problems in a particular situation  often require a combination of approaches. The bottom line is cost, safety, effectiveness, and environmental impact.

The following are a couple of examples of ozone use for odor reduction in wastewater applications:

Easy To Digest: H2S Removal Rids City Of Lift Station Odors” By Richard Wiseman, Street & Sewer Superintendent, City of Taylorville  published in Wateronline.com

Application of Ozone and Oxygen to Reduce Chemical Oxygen Demand and Hydrogen Sulfide from a Recovered Paper Processing Plant”  by Patricia A. Terry  Research Article  International Journal of Chemical Engineering  Volume 2010, Article ID 250235, 6 pages

Oxidation Technologies specializes in integrating ozone into existing systems. We also offer custom built rental equipment for pilot tests to help determine if ozone a good fit for your situation.

At the particular site I visited, sewage is being pumped over 15 miles. Without treatment, hydrogen sulfide gas is generated from the anaerobic conditions within the pipe. Gasses are vented at various points along the pipe often leading to odor problems. The idea is to provide the pipeline with sufficient oxygen to prevent anaerobic activity. Currently this site is using a combination of Bioxide and ozone to control odor problems. Bioxide is a calcium nitrate based liquid formula which creates a thriving environment for bacteria that remove dissolved hydrogen sulfide and prevents its formation.  The liquid solution is metered into the sewage main at rates from 1 to 8 gallons per hour depending on sewage flow rates and ozone use. Ozone gas also provides oxygen needed by the aerobic bacteria helping to break down the sewage. Ozone destroys the odor causing bacteria, breaks down odors and organic material as ozone releases its energy and transforms back to oxygen. Both ozone and Bioxide provide chemical free solution with minimal residual byproducts.

Ozone comes with a higher startup cost due to the ozone generating equipment investment, but lower long term costs. Proper application and integration reduces the need for other treatment costs. A combination of treatment options is often needed to address the complexities of water treatment and variations in treatment demand throughout a year. Oxidation Technologies will custom design a system to fit your specific needs and provide routine maintenance to keep it running effectively.

Why Destroy Ozone?

 

Gleanings and Reflections of an ozone student.

High quality ozone is worth its weight in gold. Ozone is increasingly recognized as an effective green alternative to disinfection chemicals. More and more of this valuable substance is being generated and used in the world. So if ozone is so valuable, why is an ozone

destruct unit integrated into most ozone generating equipment?

Ozone is valuable when it is in the right place at the right time. Dissolved in contaminated water, ozone will break down pathogens and harmful chemicals. Floating in the air we breathe, excessive ozone irritates our sensitive airways and begins to oxidize materials. Generated by ultraviolet light in the stratosphere, ozone shields the earth from harmful solar radiation. As a biproduct of breaking down automotive pollutants with solar energy, ozone adds to the discomfort of breathing stagnant air trapped around metropolitan areas. Responsible use of ozone ensures that this valuable resource stays confined to its location of use. Often this means that unused, diluted, and contaminated ozone is destroyed.

Destroying ozone is as simple as causing it to react and breaking back into oxygen molecules.

How does it work? Keep in mind that ozone is simply three atoms of oxygen bonded together with a lot of energy.

Each molecule is like a mousetrap that has been set. It doesn’t take much to trip the trigger, break the bond, release the energy, and fall back into the more stable two atom configuration we call oxygen.

Whenever ozone is being used in an application, the energy is being released to do the work desired of breaking down the compounds we need broken down.

Typically as the ozone reacts, the oxygen atoms bond with the broken parts of the molecule to form H20, C02, etc.

There are some substances that will break the ozone apart without being broken itself. A substance that does this is called a catalyst. That catalytic converter on an automobile is another example. A catalytic converter breaks down toxic gasses from combustion into less toxic compounds. One such substance that breaks down ozone is a mixture of manganese dioxide and copper oxide. This compound is manufactured by Carus Corporation under the name Carulite. It looks like dark brown gravel. It very effectively breaks ozone down to oxygen without being destroyed itself. It is non-toxic and will not burn or generate harmful gasses as a byproduct.

We manufacture a range of sizes to match the ozone destruct demand.

A very efficient and effective design is a stainless steel can shape with a pipe thread fitting on the bottom, and a flange to bolt a lid on. This design is very safe, long lasting, and easy to service. A stainless steel sieve at the bottom inlet side holds the Carulite about an inch from the bottom. This allows the ozone to flow evenly through the Carulite material above it. If the ozone is off-gasing from water or from any other wet source, this space at the bottom can be heated so that this moisture does not condense in the Carulite and shorten its life.

The catalytic action of breaking ozone down releases heat energy which is safely dissipated with the heavy gauge stainless steel housing. Virtually all the ozone is turned back to oxygen which flows from the top of the device.

If you have any questions, comments, or additional information, feel free to comment. The Oxidation Technologies website has more details and contact information. We are always happy to answer questions and listen to your needs. We would love to help you harness the power of ozone for your application.

Flow-Meter Quiz

Efficient and accurate ozone production requires accurate measurements of gas flow rates. The rota-meter style flow-meter is a simple, robust, and accurate way to measure the flow of gas or liquid.   The only moving part is a metal ball (float) within a tapered transparent tube.  As flow rate increases, the ball rises.  Try out this quick, one-question quiz to test your ability to read this instrument.

One limitation to this device is its inability to factor in gas pressure in a direct reading.  Gas under pressure is squeezed together so more gas is able to flow past the ball than it reads.  Some flow-meters are calibrated for a specific gas pressure.  Such meters are accurate only at that pressure.  This limitation is easily overcome with a simple calculation.   You can calculate an accurate flow rate at any pressure when you  know the gas pressure of the gas flowing through the meter.  How did you do on the quiz?  If you haven’t tried it yet, check out our calculator page for better chance of getting it right.

 

Cool Colors in Oxidation

Our lab was doing some ozone exposure testing on a water sample and I noticed a beautiful magenta color developing. Toward the end of the exposure test, the foam in the water column began to take on a pinkish color. When the ozone was turned off, the foam quickly reduced to the magenta colored liquid you see in the picture. After a few minutes, it became colorless again. Intrigued, I asked why it changed colors, and learned that it had to do with Manganese Dioxide. I did some further research, and learned that Manganese has a number of oxidation states from +2 to +7. Manganese is often found dissolved in water. As such it can not be filtered from the water. Ozone will oxidize the manganese to manganese dioxide MnO2 which is particulate and can then be filtered from water. Further ozone exposure as was done in the water sample eventually forms soluble permanganate MnO4- which has a purplish color.  See our water treatment equipment for removal of iron and manganese from well water.

Last year we did some lab testing that required water with a dissolved ozone concentration over 100 ppm. https://www.oxidationtech.com/blog/the-color-of-ozone/. Here we could distinctly see the bluish color of ozone. The intense colors only hint at the power of ozone even in much lower concentrations.

For further study and research into water treatment and manganese removal, see the International Ozone Association website and links to research.

Equipment used for water sample exposure test.

Specialized Ozone Applications, Oxidation Technologies, and The Tip of the Iceberg

Oxidation Technologies will custom build a wide variety of specialized ozone applications. In the 9 months I have been working here, few projects have been the same. We have designed and built specialized pilot systems for customers exploring the new applications for ozone in their industry. We’ve produced a variety of systems for sanitation in the food industry and organic food storage. Our systems are solving tough problems in the pet products industry, and pharmaceutical research. We design systems for applications from bottled water treatment & dairy operations to municipal water, groundwater remediation, and sewage treatment. Our systems are helping customers in the ocean well drilling as well as the airline industry. We have designed custom treatment chambers for laboratories, allergy treatment, and product treatment. We’ve done in-house materials testing on a variety of dry and liquid materials. We continue to develop precise and safe control systems. Oxidation Technologies support the whole spectrum of ozone as well as other gas use with analyzers, sensors, parts and supplies. We have worked with customers all around the world. Everyone here works hard to understand needs and develop systems that will meet those needs. The leadership here have a tenacious spirit for overcoming obstacles and refuse to give up. The phones here are always in use providing excellent customer service. We are willing to travel and visit sites when needed or on a routine maintenance basis. From design to build, every project is steeped in cost consciousness, quality, the best materials and equipment for the job. Systems are built to work well, and last for a long time. After nine months working here, I continue to grow in my appreciation for the amazing potential of ozone, the depth of expertise laying the foundation of Oxidation Technologies, and the integrity and enthusiasm for applying the power of ozone to meet customers’ needs. At the same time, I have come to realize that what I have seen so far is only the tip of the iceberg. I am confident that the culture of growth and learning here will nourish my growth in understanding ozone and our ability to harness the power of ozone for your needs.

How to Install a Venturi Wrong: Learning to Harness Ozone and Venturi Injection Principles to Clean up Dirty Well Water

 

Computer simulation of Mazzei injector.

So a customer puts up a new house in the country. Water is supplied by well from old house that had been on site. Unfortunately, the well is pushing up some sediment and bacterial contamination.  One possible solution is to put in a new deeper well in the hopes of finding cleaner water.  Another, much less expensive solution is to use filtration and harness the power of ozone to purify the water.

 

The simplest setup includes a Mazzei venturi which uses the existing water flow to pull ozone into the water stream.  A small mixing tank would increase contact time for disinfection before use in the home.

This would be a perfect project for me, the apprentice.  I put the system together and brought it out for the install.  Having worked in our shop putting together a number of industrial systems, I was confident it would work well.  Plumbing was complete.  I flipped the pump breaker switch and water began flowing.  My balance barometer indicated some suction and the ozone generator light kicked on …. and then it turned off again as the water pressure increased.  What was wrong?

 

A Mazzei venturi injector is at the heart of this system.   The small plastic venturis we often use are very simple, but the careful and precise design makes them very reliable and effective.    Essentially they use some of the energy from the water flow to create a suction that will pull a gas into the water stream.  Two pressure gauges, one before the venturi and one after the venturi will demonstrate this loss of energy in the water flow.  The lost energy is being used to pull gas into the water stream.   Injectors need to be built to fit specific water flows and pressure.  Your water flow in gpm and pressure requirements will help determine which injector will work.  Mazzei has a chart for each type of injector that will tell how much gas flow is created for a range of pressures.

 

 

So, back to my system install and what was wrong.  When I referenced my pressures before and after the injector to the Mazzei chart, I could see that my water flow was insufficient.  I tried a smaller injector which improved the range at which suction was created, but it still was not enough to get the ozone I needed in the water.  The Mazzei performance chart indicated that the well pump moved about 5 gallons per minute. When the pressure switch on the well pump sensed low water pressure, it turns the pump on.  The venturi worked at first, but as the pressure in the system increased to the point when the pressure switch turned the pump off, the venturi quit working.  So how can I increase the time ozone is injected?

I had an idea.  If the venturi was working better at low pressures, then adjust the pressure switch so that it allowed the water pressure to get lower before it turned on.  I adjusted the switch to turn on at 35 psi instead of 45 and the venturi was able to pull in ozone until it reached 47 psi.  The pump continued to pump till the switch turned it off at 75 psi.  This water mixed with the ozonated water in the tank.  Dissolved ozone measurements indicated adequate concentrations under ideal conditions.  But sometimes water use keeps the pump running at a pressure where no ozone is being injected.  That simply was not going to work.  I left for the day, and got a call the next morning from the customer.  The water pressure in the house was not going to work for three teenage girls getting ready for school in the morning.

 

The well pump was not creating enough flow to make the system work.  I needed to add a pump to increase flow.  Flow from the well cannot be increased, so the pump would circulate 15 gpm through a loop.   I turned the pressure switch back up and installed a pump wired to turn on when the well pump turned on.   I plumbed to pull water at a T from the bottom of the tank where the pressure switch and bladder tank were hooked up and push it through a T where the well water was coming in.

Sketch of circulation pump design

 

Again I turned on the pump breaker switch.  My new pump began to circulate water, balance barometer indicated some suction, ozone generator turned on, …. but only for a while.  The system was not working any better than before!  And a new problem surfaced: the well pump took longer to turn off because the new pump inlet reduced the pressure at the pressure switch.

 

After pondering this problem and looking at other system diagrams, it seemed to me that the venturi should come before the water inlet from the well pump. More plumbing changes. Multiple venturi size tests. But I still not able to get the flow and pressure differential I needed when the well pump was running. I noticed that if I turned the breaker off for the well pump, I was able to get good suction with just the circulation pump running.

 

A venturi will work only if you can maintain a pressure differential between the inlet and the outlet.  Even with the well pump adding into the circulation pump outlet, the system configuration was not creating the flow needed through the venturi.  If I understand it correctly, the well pump seemed to be fighting against the circulation pump.

 

It would be better if the well pump was feeding water into the system just before the circulation pump.  This would level the pressure “playing field” across the loop before the circulation pump pulled well water and some water from the mixing tank through the venturi.  Again I flipped the well pump breaker switch.  This time the balance barometer showed a healthy level of suction.  The ozone generator kicked on.  As the pressure increased, the suction reduced but it stayed on until the well pump turned off.  This is what I was looking for!  Now it was working.

Completed Working System – note the balance barometer and pressure gauges.

Learning How to Harness the Power of Ozone – The Balance Barometer

A balance barometer is a very simple device that provides fool-proof protection of ozone generating equipment in a venturi injection system.   As someone new to the ozone industry learning how to harness the power of ozone, I was intrigued by the balance barometer I was asked to construct for one of our systems.  How does it work?  Why are they useful?   Is there anything particular about the dimensions that make it work properly?

 

A balance barometer is used to keep water from backing up into the output side of an ozone generator.  Corona discharge ozone generators will reliably generate ozone if, and only if, they stay very dry.  Any moisture coming into the ozone generator will shorten its life.   In a system where a venturi is used to inject and dissolve ozone in water, a catastrophic flood of water into the ozone generator is always only seconds away.  Critical to the success of any such system is that point between the ozone generator and injecting the ozone into the water stream.

 

Under normal operating conditions, the venturi through which water is forced will create suction and prevent any water from flowing back to the ozone generator.  This water will immediately flow to the generator if water flow is reduced or stops in the venturi.  A simple check valve is built into Mazzei venturis to prevent this backflow.  An additional series of stainless steel and Kynar check valves will stop or slow this water most of the time.   But even “slowing the water” or “most of the time” is a risk that can be eliminated with a simple balance barometer.

 

A balance barometer is a U shaped tube with one side about twice as high as the other.  The top of the high side is capped off, and two holes are drilled into the cap: one straight down from the top, and one in the side at the bottom edge of the cap for ozone tube fittings. One inch clear PVC works well for visual monitoring, and the diameter allows bubbles and water to pass by one another without hindering its performance.

 

So let’s hook it up to see how it works.  The very top fitting goes to the ozone generator, and the side fitting just below the top fitting goes to the venturi suction port in our system.  If sufficient water flows through the venturi, it will begin to draw air through the check valves, ozone generator, and balance barometer.  If we put some water in the balance barometer, it will block off air flow through it and force all the flow to pull through the ozone generator.  This would be the normal operation.

 

Now if the particular water system has some water pressure when water isn’t flowing through the venturi, as in a well water system, water will be forced back out the injection port.  The check valve should prevent water back flow, but if ozone has deteriorated the seal or a tiny speck of something prevents a tight seal, water will begin to flow past it and toward the ozone generator.  When it reaches the balance barometer, it will simply add water to it until the short end overflows.  Once water flow is restored to the venturi, the suction will return.  Any water in the line or extra water in the barometer will be sucked into the venturi and normal operation resumes.

 

The balance barometer works well with ozone generators that operate under very low pressure or a slight vacuum.  Only 1 psi of pressure or vacuum will balance with 27 inches of water making the minimum size short side of the tube for such a system 27 inches.  Systems that simply use the venturi to pull air through the ozone generator work well with a balance barometer.  If a balance barometer is not practical for a particular application, our stainless steel backflow preventer will provide the same type of protection using a built-in float.