How Does a Fan Filter Unit Work

by Technical Air Products

A cleanroom is not a cleanroom without its fan filter units; they are a critical component of the room’s design. In this blog piece we will discuss how a fan filter unit works and the different types of FFU’s that we offer. Selecting the right one for your cleanroom will depend on what your needs are in terms of price, energy efficiency, performance, and control. 

What is a Fan Filter Unit? 

A fan filter unit is a motorized filtration system that works to supply clean, filtered air continuously to the cleanroom. These units are mounted within the room’s ceiling grid and operate independently, or in conjunction with an HVAC system. The airflow in the cleanroom is designed to direct air to vents in the floor or walls where it is exhausted out of the room, or returned back to the fan filter units in the ceiling

Depending on the size of your cleanroom, FFU’s can be added or subtracted in order to meet the necessary ISO Class requirements. Typically, the more stringent the cleanliness requirements of the cleanroom, the more fan filter units will be needed. 

The air is drawn in through the fan, first through a prefilter and then typically through either a HEPA (High Efficiency Particulate Air) or ULPA (Ultra-low Particulate Air) filter. These two types of filters screen out airborne particles which, along with the frequency of air changes, ensures that the air in the room is cleaned to specification. 

Different Types of FFU’s

Technical Air Products manufactures four types of fan filter units. Your choice will depend on your specific needs as well as any limitations you may have. Most of the following units can be built to run at 120V-277V. They can all be made with standard filters, or with room-side replaceable (RSR) filters. Standard features include 20-gauge steel construction, powder-coated white finish, a 30% efficient ASHRAE 1” prefilter, onboard variable speed controls, and 8-foot power cords. However, several different options are available to meet your needs.

SPXThe SPX is our standard fan filter unit. It offers customers a great combination of price, performance, and quiet operation. This is our most affordably priced FFU. It can reliably deliver over 700 CFM from a 1/4 HP permanent split capacitor (PSC) motor.

Energy Efficient – For our most energy-efficient unit, we offer the SPX-EE. This FFU can deliver over 800 CFM, while operating under 200 watts. The 120V EE fan filter unit is UL listed and is perfect for any application in which power conservation is important. The SPX-EE utilizes a 1/4 HP backward-curved impeller.

Electronically Commutated – The SPX-EC is Technical Air Products’ most feature rich FFU.  It utilizes a 1/3 HP electronically commutated, variable speed motor (ECM). It comes standard with a basic control card with manual RPM adjustment, but an optional full-feature, auto-control card can be used, along with sensors and graphical-interface consoles, for varying degrees of automation and room monitoring. For example, the variable speed motor can be set up to automatically ramp up or down motor RPM to keep a consistent air flow as the final filter starts to get loaded with particulate. 

High Horsepower – If maximizing air flow is what you need, our SPX-HP fan filter unit will perform. The SPX-HP boasts a maximum air flow of 1,000 CFM. With a powerful ½ HP motor, the SPX-HP FFU has the least amount of CFM drop when used with more efficient filter media. For instance, the SPX-HP still delivers over 900 CFM when used with a high-efficiency ULPA filter.

If your organization needs a fan filter unit, whether multiple units for a new cleanroom installation or a replacement unit for your established cleanroom, Technical Air Products has what you need. Our FFU’s perform exceptionally well and are competitively priced. They have been extensively tested to ensure they operate well above cleanroom industry standards. Please take some time to look over our FFU options. Each of our four FFU models can provide either HEPA or ULPA filtered air to any environment.

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