Cleanrooms Fan Filter Units

Structure of FFUs

FFUs come in 2’x2’, 3’x2’ or 4’x2’ dimension metal housing. The FFU component has a pre-filter and may also feature one of the following additional filters:

• High-Efficiency Particulate Air (HEPA) filter: removes impurities that are 0.3 um (micrometre or micron) or greater in size. HEPA has a 99.99% efficiency rating.
• Ultra-Low Particulate Air (ULPA) filter: removes impurities that are 0.12 um or greater in size. ULPA filters have an efficiency rating of 99.999%
• Minimum Efficiency Reporting Value (MERV) filter: removes impurities in the range of 0.3 to 10 micrometres.

Reasons to deploy FFUs

• FFUs are the only units that can fit into smaller internal floor dimensions, because they have less height restrictions.
• FFUs are easy to install and require no retrofitting. It’s easy to update contamination control systems without having to restructure walls. They easily sit above workbenches, as they are easy to move.
• Unlike traditional airflow systems, FFUs are more portable and make it easier for technicians to make quick updates.
• FFUs are less expensive compared with conventional recirculating air units.

Types of FFUs

Micro-Sound Fan Filter Units

• These come with a 99.99% efficient HEPA filter, seismic clip points, safety switch for unit maintenance/servicing and a speed control to allow for airflow tuning.
• The energy-saving N310 motor blower has a low watt curved impeller. It is single phase with a permanent split capacitor.
• Housings are made from steel, which comes in a white coat finish. Meanwhile, filters come in a white epoxy finish.
• Units come in 277 Volt (60 Hz), 208-230 Volt (50/60 Hz, which is available on request) and 115 Volt (60 Hz).

Pharmaceutical-Style Fan Filter Units

These types of FFUs are sometimes called Room-side Replaceable Fan Filter Units. These FFUs are deployed by medical device manufacturers and pharmaceutical companies. On the upstream end of the final filter lies a gel, which has a leak-free seal.

This FFU has a HEPA or ULPA replaceable filter. The filter can be removed from the unit without taking it out of the ceiling, due to the fact there is an accessible polystyrene grille.

FFUs come with a 99.99% HEPA filter.

• Access Port: the port is located in the centre of the filter face and used for measuring static pressure.
• Standard Ceiling Size: models come in 2’ x 4’ to fit a nominal 2’ x 4’ grid with a standard opening of 22.5’’ x 46.5’’.
• Air flow range: the range is between 220 to 340 CFM for a 2’ x 2’unit and 340 to 640 CFM for a 2’ x 4’.
• Sound Level: approximately 54 dba with an ambient sound level less than 45 dba. This is achieved with a face velocity of 90 FPM.

Constant Output Unit

This type of FFUs automatically adjust to maintain airflow.

Performance features include:

• A digital speed display for a quick read.
• A low power consumption rating.
• Airflow can be set with a potentiometer.
• An electronic commutative motor, which helps maintain constant airflow. The motor is programmed to adjust to alternating loads by adjusting its speed.

Hazardous Location Units

Hazardous Location FFUs provide clean air to systems where the air is polluted.

• For these FFUs to be ideal in hazardous locations, they come with explosion-proof ratings (known as AMCA Type B Construction) for its electrical parts.
• FFUs come with a blower wheel that’ made of spark-resistant aluminum.
• Comes with a pre-filter and a 99.99% effective HEPA filter.

Stainless Steel Units

These FFUs have fabrication housings #304 stainless steel, as well as a #4 finish. Features include:

• Ability to fine tune airflow with a solid state variable speed control and RFI suppression.
• HEPA filter at 99.99% efficiency level.
• Safety switch to power off the unit while it’s being serviced.

Fan Filter Control System

The FFU control systems adjust units from remote system locations. A network can be set up, enabling an operator to adjust air flow to a concentrated location. This method of remotely re-adjusting air flow helps cost reduction. These FFU control systems utilise 115V and 277V motor blower units. These units are standardised and have the advantage of avoiding the high cost of DC motors.

FFU control systems are made up of an address or several addresses. A wall-mounted console controls addresses with four or more FFUs in an address.

Each address is made up of the following:

• HEPA or ULPA Filters with 53mm media packs.
• Groups of 4 SAM units that are wired.
• Mounted control consoles with LED readable features. The console should be user-friendly.
• Motor blower unit, that should come in either 115V or 277V AC impeller options.
• Units of 4 SAM and 24 FFUs, made up of 1 Master and 3 Slave Units.

Features of FFU control systems

Accurate control for airflow:

• Fan speed should be controlled from outside the Cleanroom. This can be done without coming into conflict with any rules and policies pertaining to the Cleanroom. Fan speed control should be carried out from an individual address, a zone beyond the Cleanroom or globally.
• Addresses that can be used for control should be almost limitless.
• The Cleanroom layout should be easy to configure.
• There should be an ability to control fan filter units, either collectively or individually. A collective unit is usually made up of 1 to 4 units per address.

Affordable and low maintenance costs:

• Cleanrooms should have easy-to-read recalibration and balancing information.
• Shutdown for isolated zones should be possible, without disrupting the entire Cleanroom. Isolated shutdowns would be required during maintenance or upgrade periods.

Link options for better efficiency:

• Integral wiring that comes in junction boxes reduces onsite electrical work.
• There is better operating efficiency for HEPA or ULPA filters; choose filters that have 70mm pleated design.
• Choose NCR or CRF FFUs for better operating efficiency.