A high-temperature filter, as the name suggests, is an air filter that can work in a high-temperature environment above 120 degrees. According to the filtration efficiency, it can be divided into primary effect G4 high-temperature filter, medium effect F8 high-temperature filter, and HEPA H13 H14 high-temperature filter.
High-temperature filters can only meet temperature resistance purposes by using stainless steel shells, high-temperature filter materials such as glass fiber, and high-temperature-resistant sealants, making their prices more expensive than ordinary air filters.
I want to emphasize that all current high-temperature filters are often used in industrial fields. It’s a little in civilian use.
High-temperature filters are used in ovens and other equipment and systems that require high-temperature air purification, such as pharmaceutical infusion production lines, food, chemical industry, electronics, film, industrial sector sterilization, drying, and other environments.
Hints before using a high-temperature air filter
Because the organic silica gel and inorganic sealant used in high-temperature air filters are cured from the surface inwards during the curing process, the thicker the sealant is injected, the more difficult it is to cure. Under normal circumstances, the curing time of the glue is 3-7 days.
Suppose a high-temperature HEPA filter with incompletely cured sealant is installed directly into the equipment. In that case, it will inevitably cause the glue to crack, expand, and detach from the outer frame. The high-temperature filter will lose its function.
Therefore, you need to do the following:
1. The high-temperature HEPA filter must generally be used after seven days.
2. If you need to install it immediately, it is recommended that you follow the below methods before using the high-temperature air filter:
250℃ high-temperature filter
Step1. The high-temperature air filter is slowly heated to 100°C in the oven or other high-temperature equipment, kept at a constant temperature for 2 hours, then shut down for cooling.
Step2. Adjust the temperature to 150℃ and then stop to cool down after 1 hour.
Step3. Adjust the temperature to 200℃ and then stop to cool down after 1 hour.
Step4. Adjust the temperature to 250℃ and then stop to cool down after 1 hour.
Step5. After the final slow cooling, it can be used.
350-400℃ high-temperature filter
Step1. The high-temperature air filter is slowly heated to 100°C in the oven or other high-temperature equipment, kept at a constant temperature for 2 hours, then shut down for cooling.
Step2. Adjust the temperature to 150℃ and then stop to cool down after 1 hour.
Step3. Adjust the temperature to 200℃ and then stop to cool down after 1 hour.
Step4. Adjust the temperature to 250℃ and then stop to cool down after 1 hour.
Step5. Adjust the temperature to 300℃ and then stop to cool down after 1 hour.
Step6. Adjust the temperature to 350℃ and then stop to cool down after 1 hour.
Step7. Adjust the temperature to 400℃ and then stop to cool down after 1 hour.
Step8. After the final slow cooling, it can be used.
High-temperature filters have nothing to do with our daily lives, but sometimes we encounter them. For example, some families have clean ovens, and they are inside the clean ovens.
Case study 1: High-temperature filter in Industrial oven
First of all, not all industrial ovens use air filters. Only equipment with higher air quality requirements in the baking environment will use air filters.
An industrial oven is a general drying equipment in industrial applications. It is widely used in UV spray curing, food batch automatic drying production lines, and other industries.
The main principle is to control the temperature of the oven cavity through the connection of the numerical control instrument and the temperature sensor and use the hot air circulation supply method to adjust the temperature.
The hot air circulation system is divided into two types: horizontal type and vertical type. If the air supply system’s air quality has specific needs, a high-temperature filter will be used to ensure that the air entering the oven is clean and will not pollute the product.
In addition, the used air is sucked into the air duct and becomes an air source for recirculation and heating, which can effectively improve the temperature uniformity. Similarly, before hot air enters the air duct, it also needs a high-temperature filter to filter it again to ensure that the air is clean before entering the air duct.
Case study 2: High-temperature filter in Dry heat sterilization tunnel
Pyrogens, also known as bacterial pyrogens, are metabolites of some microorganisms, bacterial corpses, and endotoxins. Common disinfectants such as hydrogen peroxide cannot eliminate pyrogens, and due to the intense heat resistance of pyrogens, it is difficult for moist heat sterilization equipment to destroy their activity completely. Therefore, the dry heat sterilization tunnel has become a specialized pyrogen removal equipment because only dry heat sterilization can effectively remove pyrogens.
Dry heat sterilization tunnel
A dry heat sterilization tunnel is a critical process equipment that plays a vital role in medicine, food, and other industries. The dry heat sterilization method can ensure the sterility and quality of the product. It can be said that it is essential in the filling line of aseptic production.
This sterilization tunnel uses dry hot air to heat the filling container to achieve rapid sterilization and depyrogenation. The sterilization temperature is usually between 160°C and 180°C to ensure that the product does not contain active microorganisms, while the depyrogenation temperature is generally between 200°C and 350°C. According to regulations, dry heat sterilization at 250°C × 45 minutes is required to remove pyrogenic substances in sterile product packaging containers effectively.
How to ensure the cleanliness of a dry heat sterilization tunnel?
Here, I put it: use high-temperature filters.
The dry heat sterilization tunnel material is usually stainless steel, and the box’s inner and outer surfaces must be polished, flat, smooth, and without bumps and scratches. The fan applied in the high-temperature section must withstand temperatures up to 400°C.
At the same time, the sterilization tunnel also needs to have functions such as temperature monitoring, recording, printing, and alarming, as well as wind pressure monitoring and online sterilization functions for each section.
Why does a dry heat sterilization tunnel need a high-temperature filter?
According to GMP regulations, dry heat sterilization tunnels are installed in Class A areas, and the cleanliness of the work area is required to reach Class 100. Due to its exceptional high-temperature environment, the dry heat sterilization tunnel must select a high-temperature HEPA filter at least H14 level to meet this requirement.
The high-temperature HEPA filter is critical in the dry heat sterilization tunnel. The heated high-temperature air must pass through the filter to ensure that the cleanliness reaches level 100 and meets the GMP requirements.
At the same time, using high-temperature HEPA filters can minimize contamination by microorganisms, particulates, and pyrogens.
How do you set high-temperature HEPA filters for a dry heat sterilization tunnel?
The high-temperature area inside the tunnel oven is subdivided into a preheating section, a high-temperature heating section, and a cooling section. Each area is equipped with high-temperature filters of different temperatures. The preheating and cooling sections are usually equipped with 150℃ or 250℃ high-temperature HEPA filters, and the heating section must be equipped with 350℃ high-temperature HEPA filters.
Last thought
In most cases, H14 is selected for high-temperature HEPA filters. Like all HEPA filters, they must be scanned and tested one by one before delivery. In addition, high-temperature resistance tests must be conducted to ensure they can operate in the specified high-temperature environment.
