Quality Engineered Structures Filtration Image 1

Cleanroom Filtration Systems
HEPA, ULPA, filter bank modules

Quality Engineered Structures Filtration Image 2 Cleanroom filtration systems, appropriately designed to work in conjunction with the air handling system, deliver the particulate free environment required by high quality process functions. The filter type, filter airflow, and filter placement in the cleanroom system will ultimately determine the ISO cleanliness classification of the cleanroom environment.

Airflow cleanliness classification is an accomplishment of filter coverage, airflow rates of exchange, and filter media type. The amount of filter coverage and airflow will also determine the cleanroom recovery rate.

Cleanroom Filtration Modules:
  • Cleanroom Pre-Filters with a 30% to 65% efficiency rating and minimum efficiency reporting value(MERV) rating over 7 should be installed in the return air supply of the cleanroom and should also should also be the initial filtration modules in the air handling unit supply chamber. Pre filtering the cleanroom airflow will substantially extend the productive service life of the high-efficiency filters(HEPA) and decrease energy consumption. Energy Cost Index, or “ECI,” is a filter rating system that looks at the filter’s efficiency over its lifetime and the energy required to move air through that filter.

  • Cleanroom High Efficiency Particulate Air(HEPA) Filtration remove at least 99.97% of airborne particles 0.3 micrometers (µm) in diameter. Filters are rated by the European Norm EN 1822:2009 and can go up to 99.999995 % filtration of airborne particles 0.3 micrometers (µm) in diameter. The process typically dictates the level of filtration required. Filters are available in terminal end units, without fans, fan forced units(FFU), and flow through units designed to work with HEPA bank systems in the air handling equipment.

  • Cleanroom Ultra Low Particulate Air(ULPA) Filtration can remove from the air at least 99.999% of dust, pollen, mold, bacteria and any airborne particles with a size of 120 nanometres or larger. They are designed to meet the requirement for cleaner air in facilities needed for the manufacture of microelectronics.

  • Electrostatic Precipitator (ESP) type Filtration Systems offer two stage electrostatic air filtration. Fine sub-micron suspended particles are electrostatically charged using high-voltage electric field, which then get attracted and precipitated on opposite charged electrode plates. Particularly useful in assisting in the control of microbial bioburden cross contamination.

Cleanroom filtration design should be dictated by the process and process equipment to be installed in the cleanroom environment. Typical tables for and air changes required typically are based on an empty cleanroom at rest. Depending on the process and procedures that will take place in the cleanroom environment the correct amount of filter coverage and air changes can increase. Engineering should take into account the process, process equipment, number of personnel, amount of entry and egress, and ambient environment when determining the final filter coverage and air change rate. Air cleanliness should also be tested at operating levels to assure compliance with the specifications.

Cleanroom filter maintenance depending on the filter installation can be a time consuming process leading to excessive downtime with some lower cost filtration units. Filters are tested by a series of procedures defined in ISO 14644-1, ISO 14644-2, and ISO 14644-3 specifications by the Institute of Environmental Sciences and Technology(IEST). To minimize downtime for testing and maintenance it is recommended that you utilize only room side replaceable(RSR) style modules.

Cleanroom filtration systems should be designed and engineered to match the process they are specified for. Various cleanroom environments and processes dictate specific types of filter efficiencies be in place to meet certification and validation requirements.

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