How to choose FFU filter for ISO 5 clean room? Do I have to use ULPA?
Direct answer: ISO 5 does not directly specify whether FFU must use HEPA or ULPA. Filters should be selected based on process particle control requirements, target air volume, design resistance, sealing and inspection requirements. If the filtration efficiency level is improved, the actual air volume of the FFU after installing the filter must be rechecked, and the cleanliness target must be verified through on-site particle concentration testing.
ISO 14644-1 classifies clean rooms and clean areas based on the concentration of suspended particles in the air. ISO 5 describes the air cleaning results that need to be achieved , and cannot alone determine the model of a certain filter. SelectWhen using HEPA or ULPA air filters , process, air supply and installation conditions must also be considered.
First question: Does ISO 5 require coverage of the entire room or a local process area?
If the entire room is required to meet ISO 5, the filtration plan should be determined based on the air supply layout of the whole room, dust generation by personnel and equipment, and the return air path. If the requirements are mainly concentrated near the equipment, the scope of the local clean area and the air supply conditions at the equipment end should be clearly defined.
The two types of projects may use different FFU arrangements and filter configurations. We cannot just rely on the three words 'ISO 5' to designate all locations as ULPA filters; nor can we ignore the more stringent particle control requirements in key process areas.
Look again: after the filter is installed in the FFU, is the air volume still enough?
The filter data should indicate the efficiency testing conditions and the initial resistance at the design air volume . Install the filterAfter the FFU fan filter unit , it should be checked whether the entire machine can achieve the target air volume under the project operating gear and resistance conditions.
If the project is selectedFor ULPA filters , or upgrading the filtration level from the original solution, it is necessary to simultaneously review the fan operating point, power consumption and wind speed distribution. Higher filtration efficiency cannot replace adequate air supply and reasonable airflow organization.
Last look: Can it be sealed, inspected and replaced?
The overall dimensions, frame and sealing method of the filter should match the FFU box. The project should also clarify filter testing data, sealing inspection requirements after installation, and space for maintenance and replacement on the ceiling or equipment side. The filter itself is qualified, but leakage at the installation site will still affect the actual cleaning effect.
During acceptance, the FFU air volume, airflow distribution and particle concentration should be checked under the operating conditions specified in the technical agreement. Cleanroom performance testing should also use methods that are suitable for the airflow type and operating conditions; ISO 14644-3 provides a corresponding test method framework.
Aili Industrial can combine the ISO 5 area scope, process particle control requirements, target air volume and installation conditions to match filters, fans, motors and box structures. For batch projects, it is recommended to first use a prototype to confirm the filter sealing and overall machine performance, and then write the filter configuration, test conditions and on-site acceptance requirements into the technical agreement. The specific configuration is subject to project working conditions and test results.
The key to judging whether ULPA is needed is not the grade name itself, but the particle control requirements of the project, the air supply capacity of the complete machine and the on-site verification results.
