Ozone removal filter series Part 1. - Air purifier application
<Air purifier application>
Due to the spread of Covid-19, there has been an increasing demand for air purifiers in various settings. Hospitals, as well as homeowners alike, are trying to eliminate the risks of airborne pollutants.
There are currently two main types of air purifiers used for these purposes with potential alternatives being developed.
One of the main types is the plasma air purifier, which uses high voltage to sterilize the air. In the process, the contact between UV and oxygen generates ozone which without proper control may be released into the ambient air.
The other type of air purifier uses ozone itself to eradicate any airborne pollutants.
In either case, an ozone removal filter is necessary. Its principal function is to control the ozone concentration so that no inappropriate levels harmful to people are released from the system.
NICHIAS has been manufacturing and providing to the industry, filters with an ozone decomposing catalyst capable of providing the required level of control.
There are also other applications of concern. In part 2, we will look at how and why ozone removal filters are important in the surface treatment application.
Ozone removal filter series Part 2. - Surface treatment application
Select manufacturing equipment has been known to produce ozone levels during usage. To maintain safe operation, these levels need to be controlled with Ozone filters.
This is specifically relevant to plastic resin surface treatment. When the plastic resin surface is treated with corona for roughness to help adhesion, high voltage comes into contact with oxygen. This process can generate quantities of ozone which are harmful to people.
Companies often opt to use a honeycomb type removal filter with an ozone decomposing catalyst to control the ozone emission. This assures that ozone levels are maintained at levels that pose no danger.
NICHIAS has been supplying ozone removal filters for this application with expertise. Hence, for more information on this application and if an ozone removal filter is a right choice for your project, you can contact us at firstname.lastname@example.org or by using the form at the bottom of the page.
In part 3, we will look at the final application of concern where the ozone emissions also need to be managed - copier machine and laser printers.
Ozone removal filter series Part 3. - Copier machine or laser printer application
Copier machines and laser printers require the use of ozone removal filters because of their design. Especially during copying, UV light, high voltage and oxygen come into contact, which generates ozone.
In these instances, an ozone removal filter is used to control the ozone emission so that a harmful amount is not released into the ambient air. Therefore, keeping the machines safe for use.
Major copier machine and laser printer manufacturers continue to use ozone removal filters. NICHIAS has been one of the main suppliers in this industry, providing ozone removal filters to these manufacturers.
In case you have equipment that is generating ozone and are considering using an ozone removal filter, we are more than happy to discuss the details with you.
But if you would like to know more about the dangers of ozone, our technical team and the safety team have prepared an article (part 4 of this series) discussing different levels of ozone and their effects on the human body. You can find more information there.
Ozone removal filter series Part 4. - Adverse effects of ozone exposure
As discussed in previous articles, certain industries utilize ozone in their systems, or their systems generate ozone due to their function. In either case, the substance levels released into the air need to be managed due to the adverse effects of ozone on the human body.
When inhaled, ozone is a substance that can harm the human body, and prolonged exposure can lead to severe physical damage. Different concentration levels will cause different bodily responses.
The above symptoms can be attributed to ozone release into the ambient. However, when ozone concentration exceeds 20ppm, there are extreme dangers to those exposed. Thus, it is essential to control the ozone generation and limit the concentration released at the source; hence, why an ozone removal filter should be included in all relevant systems and is always recommended.
Ozone removal filter series Part 5. - Operating conditions
As explained in previous articles, ozone removal filters treat ozone concentrations harmful to the human body. The main applications include air purifiers, surface treatment machines, laser printer and copier machines.
NICHIAS has developed and supplies different types of ozone removal filters based on the applications and ozone concentrations to assure correct functioning and keep those around safe.
There are two main types that NICHIAS supply.
1. ZV This filter is recommended for applications with a concentration of 2ppm or less. At this concentration, the dangers to the body are headache, fatigue, and upper respiratory tract drying.
Applications with less than 2ppm include copier machines. The air purifying market may also fall into the '2ppm or less' category. However, it largely depends on the structure of the system.
2. ZCH2 This filter is used in applications with concentrations of 20ppm or less. These applications have more severe potential consequences, such as physical danger due to pulmonary edema.
20ppm use condition is prevalent in ozone generators and surface treatment applications. Both applications tend to have high ozone concentrations.
You can read more about the different dangers of ozone concentration in the previous article (part 4) here.
Now that we have covered the applications, dangers of ozone concentrations and operating conditions, in the next article, our technical team will cover the first of the ozone removal methods - adsorption.
*NICHIAS does not manufacture ozone removal filter for concentrations above 20ppm.
Ozone removal filter series Part 6. - Adsorption
There are two main methods of ozone treatment - adsorption and decomposition. In this article, our technical team looks at the adsorption method, how it functions and the benefits.
Adsorption is a method that adsorbs and removes ozone molecules from the processed air. The material most commonly used in adsorption is, for example, activated carbon. Activated carbon is impregnated into the substrate whereby, when in use, it holds the ozone molecules on the outside or the internal surfaces within the material. Due to that, this material may require more frequent replacement.
However, one of the main advantages of this method is the deodorizing effect favoured in the refrigeration industry. It also has a lower price compared to catalytic decomposition.
Our team will look at catalytic decomposition in the following article.
Ozone removal filter series Part 7. - Catalytic Decomposition
There are two main methods of ozone treatment - adsorption and catalytic decomposition. In this article, our technical team looks at the catalytic decomposition method, how it functions and the benefits.
When ozone molecules enter an ozone removal filter, the decomposition catalyst breaks down these ozone molecules. As a result, ozone is converted into a harmless gas that is no danger to the human body. One high-quality catalyst that NICHIAS uses is manganese dioxide to facilitate this elimination.
Unlike with adsorption, whereby ozone molecules are held on the outside or the filter substrate's internal surfaces, the decomposition catalyst functional material itself does not change.
Therefore, compared to the adsorption method, the advantage of catalytic decomposition is a longer lifetime. On the other hand, this method tends to be more expensive than the adsorption method.
If you are unsure which ozone removal method is best for your application, please get in touch.
Ozone removal filter series Part 8. - Honeycomb structure advantages
Aside from pellet-type ozone removal filters, there are also filters formed with honeycomb structure.
Honeycomb structure received its name due to its resemblance to a beehive as you can see in the photo below. However, this structure has many advantages in air processing and removing unwanted gases such as ozone.
Due to this structure, the contact area per volume unit is compact yet large. This use to contain ozone molecules between the inlet process air and the removal filter results in efficient ozone removal. As a result, it is one of the honeycomb structure's main advantages
All NICHIAS ozone removal filters have a honeycomb structure and can be more compact than the existing pellet-type ozone removal filters.
Ozone removal filter series Part 9. - Honeycomb cell types and advantages
As a manufacturer of inorganic fibre honeycomb substrates, Nichias has a wide range of cell types. The smaller the cell type, the better the ozone removal performance per unit volume. However, there is a difference between the finest cell type and the maximum cell type in terms of advantages, disadvantages, and performance achieved.
The smaller the cell type becomes, the more the pressure loss increases. That means there is more resistance against the air volume that passes through the filter. This leads to longer residence time within the filter and quicker wear down of the material.
Depending on the intended use, ozone removal efficiency will vary. To satisfy those different needs, it is necessary to select the optimum cell type for the ozone removal filter based on various factors, such as width, inlet temperature, moisture, etc. Ideal performance is therefore affected by selecting the honeycomb substrate (for example, inorganic fibre or other) and cell type.
Nichias can propose the most suitable model based on multiple cell types we can manufacture and utilise our industry experience.
* The following figure shows a selection of a few ozone filter cell types and the difference in typical ozone removal efficiency and pressure loss depending on the cell type.
Ozone removal filter series Part 10. - Inorganic carrier
There are various base materials for an ozone removal filter. As we focus on the honeycomb structured filter, there are two main types: inorganic and metal. Depending on the base material, the ozone removal filter performance will differ. In this article, we look at the inorganic carrier and its characteristics.
The base material for NICHIAS ZV and ZCH2 ozone removal filters is an inorganic substance with porosity.
When we look at the carrier under a microscope, it is clear that the inorganic fibres are entwined. The functional material that assists in ozone removal is supported in the gaps via porosity.
As a result, a large specific surface area increases the contact frequency between the processed ozone molecules and the filter. Thanks to that, a filter with an inorganic carrier can remove ozone efficiently.
Ozone removal filter series Part 11. - Metal honeycomb
There are various base materials for an ozone removal filter. As we focus on the honeycomb structured filter, there are two main types: inorganic and metal. Depending on the base material, the ozone removal filter performance and application will differ. In this article, we look at the metal (aluminum) honeycomb carrier and its characteristics.
This base material was mainly adopted for use in air purifiers. Some of the benefits of this honeycomb are its low-pressure drop as well as low voltage loss.
Regarding low-pressure drop, it is especially important in the design of equipment used in public spaces (such as air purifiers) due to its capability to reduce noise.
The low-pressure drop is achieved by the wall's texture which is smoother than an inorganic's filter; the number of cells, and cell shape. The walls are also less thick with a metal honeycomb structure and have an ideal hexagonal shape than an inorganic filter. All of this contributes to low-pressure drop.
Yet, despite its benefits, metal honeycomb base material is also more expensive than its inorganic fibre counterpart. Because of that, many manufacturers have minimum order quantities, which make metal honeycombs viable for larger-scale production.
However, the benefits of this material cannot be neglected, and NICHIAS considers it an option whenever discussing clients' project requirements.
Ozone removal filter series Part 12. - Space velocity
When designing ozone removal filter in a particular application, the technical team needs to take into account the conditions under which the filter will be used. An important aspect that determines the ozone removal performance of the filter is space velocity.
Space velocity is a concept that expresses the reaction time of ozone removal filter's performance. It is the relation between volumetric flow rate and reactor volume. On top of that, this measurement shows how often the filter comes into contact with ozone.
To calculate space velocity, it is common to use the following formula.
Space velocity (1/hr) = Air volume (m3/hr) ÷ Filter volume (m3)
The smaller the space velocity result, the better the ozone removal performance. This is due to a smaller value meaning a larger value in the denominator. In other words, the catalyst volume is large and the frequency of contact increases.
Of course, these calculations are an essential part of the filter design during the early stages of an enquiry.