Step 1: Confirm actual working parameters, the foundation of filter selection

1. Long-term continuous operating temperature of the equipment; distinguish long-term continuous temperature from instantaneous peak temperature. The long-term continuous temperature shall be used as the basis for selection instead of instantaneous peak value.

2. Thermal cycling frequency: how many heating and cooling cycles the equipment undergoes per day. Frequent alternating hot and cold conditions will accelerate the aging of sealing components.

3. Exposure to chemical media such as VHP or solvent vapor.

4. Working condition type: general industrial working condition / GMP pharmaceutical working condition. The requirements for material extractables are completely different.

5. Installation form: installed inside the oven cavity or in the external hot air circulation pipeline.

6. Verification requirements: whether hot PAO leak test, material traceability documents and EN1822 reports are required.

Step 2: Select temperature resistance grade

• Continuous operation ≤200℃: Select 200℃ grade high-temperature resistant HEPA filter. Suitable for general industrial ovens, electronic baking and food hot air drying. Not recommended for pharmaceutical dry heat tunnels.

• Continuous operation 250~280℃: Select 280℃ grade high-temperature resistant HEPA filter. Mainly used for pharmaceutical dry heat sterilization tunnels and freeze dryer high-temperature circulation. Pharmaceutical tunnel ovens must adopt 280℃ grade filters; downgraded 200℃ products are prohibited.

Note: Do not operate continuously beyond the rated temperature. Over-temperature will accelerate the aging of sealant and silicone gaskets and greatly shorten service life.

Step 3: Choose structural form

The mainstream type is the high-temperature resistant HEPA filter with separators, and aluminum foil separators are the first choice. Stainless steel separators are selected for environments with strong oxidizing atmosphere. The separator structure maintains stable mechanical performance at high temperatures, and the air flow channel is not easy to deform, which is the standard solution for pharmaceutical high-temperature equipment. Separatorless high-temperature resistant HEPA filters are limited by high-temperature adhesive lines, with few available models. They are mostly used in working conditions below 200℃ and not recommended for 280℃ pharmaceutical tunnel ovens.

Step 4: Outer frame material selection

• SUS304 stainless steel: applicable for most working conditions with good cost performance.

• SUS316L stainless steel: for working conditions with corrosive steam and high humidity corrosion, at a higher cost. Aluminum alloy frames are prohibited. Aluminum alloy loses strength and is prone to thermal deformation under high temperature.

Step 5: Sealing system configuration, distinguish industrial grade and GMP pharmaceutical grade

Industrial working conditions (200℃ ovens, general baking): High-temperature resistant silicone sealant and ordinary silicone gaskets. They meet filtration requirements without strict extractables requirements.

GMP pharmaceutical working conditions (tunnel ovens, freeze dryers):

1. Sealant: Pharmaceutical-grade silicone sealant, pre-baked at high temperature after factory production to remove volatile components.

2. Gasket: Pharmaceutical-grade low-extractable silicone gasket, resistant to repeated thermal cycles and VHP fumigation. The gasket is a key consumable part. Its material specification shall be confirmed during selection.

Step 6: Filtration efficiency grade

• H13: General industrial high-temperature hot air filtration

• H14: Pharmaceutical dry heat tunnel ovens and sterile-related high-temperature circulation systems, meeting PAO leak test requirements

Industry-Specific Selection Summary

1. Pharmaceutical Aseptic Industry ① Tunnel-type dry heat sterilization oven: 280℃ grade, H14, SUS304 frame, aluminum foil separators, pharmaceutical-grade low-extractable sealant and silicone gaskets; EN1822 test supported; normal temperature + hot PAO leak test required; complete material certificates and low-extractable statements provided. ② Freeze dryer hot air circulation: 200℃ or 280℃ grade according to actual operating temperature, H13/H14, GMP-grade sealing materials.

2. Electronics & New Energy Industrial High-Temperature Ovens Continuous temperature ≤200℃, 200℃ grade, mainly H13; SUS304 frame, separator structure; industrial-grade sealing system; normal temperature PAO leak test only, hot leak test is generally not required.

3. Food Processing Baking Hot Air Purification 200℃ grade, H13, SUS304 frame; for food-contact working conditions, confirm sealing materials comply with food contact requirements.

Constraints for Special Working Conditions

1. Frequent VHP fumigation: Adopt VHP-resistant silicone gaskets. VHP accelerates silicone aging. The replacement cycle of gaskets and filters needs to be shortened appropriately.

2. Corrosive gas environment: Prioritize SUS316L frame + stainless steel separators.

3. Frequent rapid heating & cooling: Severe working condition with faster gasket aging. Inform the supplier of thermal cycling frequency during selection to optimize gasket selection.

Verification & Procurement Technical Requirements

General industrial projects: Provide dimensions, temperature resistance, efficiency and room temperature test reports.

GMP pharmaceutical projects:

1. Clearly define the rated temperature as long-term continuous temperature; documents marked only with instantaneous peak temperature are not accepted.

2. Require material certificates and thermal extractables statements.

3. Test standard: national standard or EN1822.

4. Confirm support for room-temperature PAO leak test; tunnel oven projects require hot PAO leak test.

5. For pharmaceutical-grade products, require high-temperature pre-baking treatment at factory to remove volatile substances.

Common Selection Pitfalls

1. Only refer to instantaneous peak temperature for selection while ignoring long-term continuous operating temperature.

2. Use 200℃ grade filters for pharmaceutical tunnel ovens (downgrade application).

3. Directly apply industrial high-temperature HEPA filters to GMP pharmaceutical processes, bringing extractables contamination risks.

4. Only perform room-temperature PAO leak test and ignore hot PAO leak test.

5. Overlook gaskets, the key sealing consumables, without specifying material requirements during procurement.

Bacclean high-temperature resistant HEPA filters offer two temperature grades: 200℃ and 280℃. Products are divided into industrial grade and GMP pharmaceutical grade, mainly adopting separator structure with optional SUS304/SUS316L frames. The products comply with national standards and EN1822, and are supplied with complete material and verification documents, suitable for pharmaceutical tunnel ovens, freeze dryers and various industrial high-temperature hot air equipment.