FFUs are an alternative to HVAC systems in a less stringent class of clean rooms. FFUs are often used in projects with height restrictions, rather than HVAC systems where the installation of makeup air ducts and recirculating air needed require much more space. FFU configuration is often a cost effective option, if you don’t need to cool your room (low heat gain), since it uses the air directly from the main building. This eliminates the need for a second ceiling above your cleanroom to create a plenum.
FAQs
A Fan Filter Unit (FFU) is a self-contained ceiling-mounted module that draws in ambient or recirculating air, passes it through a pre-filter and a high-efficiency HEPA (or optionally ULPA) filter, then delivers clean air into the cleanroom or controlled environment in a downward unidirectional (laminar) flow.
In your case the unit uses the building’s main air and so eliminates the need for a full makeup air duct system.
This FFU is ideal for cleanrooms in manufacturing, laboratories, pharmaceutical, electronics or food production where a controlled contamination environment is required. Because it uses building air (rather than full HVAC makeup), it’s especially suitable where height or space is limited and the heat or cooling load is modest.
Key selection factors include:
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Cleanroom classification (e.g., ISO class) and required air changes per hour.
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Filter efficiency (HEPA vs ULPA) depending on particulate requirements.
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Motor type (AC single speed vs ECM/variable speed) if energy efficiency and variable airflow are concerns.
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Size and installation constraints (ceiling height, plenum space) since FFUs often replace duct-based systems.
Maintenance typically includes:
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Regular inspection and replacement of pre‐filters.
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Periodic replacement or integrity testing of the HEPA/ULPA filter.
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Checking the fan/motor performance and ensuring airflow uniformity.
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Ensuring the module remains well sealed and mounted correctly so that air leakage or turbulence is avoided.
Relevant standards suggest checking for uniform velocity and static pressure over time.
HEPA (High Efficiency Particulate Air) filters usually remove ~99.97% of particles of size 0.3 µm depending on standard. ULPA (Ultra Low Penetration Air) filters offer even higher efficiency (99.999%+ for smaller particles) and are used for more stringent cleanroom specifications (e.g., ISO 5 or better).
