A fan filter unit, or FFU, pulls room air through a prefilter and pushes it through a final filter. The clean-air face gives you a place to handle open culture material while the fan runs. Your hands, tools, and containers still affect the air around the work.
The first sizing question is simple: how much open work do you do at once? A 2×4 ft face accommodates plates and jars across a 48 in. width. A 3×4 ft face adds height for larger work, but it needs more wall or bench space. The housing also takes space beyond the filter face.
Read the specification in context
The 2×4 ft FFU in our catalog is listed at 24 × 48 × 13.5 in. and needs 4–6 in. behind the intake. It has a variable speed 120 V fan and a replaceable HEPA filter rated 99.99% at 0.3 microns. The 3×4 ft version is listed at 36 × 48 × 13.5 in.
Filter efficiency describes a test at a stated particle size or test method. It does not certify the cleanliness of your whole bench. Airflow describes movement through the unit at a given fan setting and resistance. A face velocity figure helps you compare settings, but the filter, prefilter, and installation all affect the air you get at the work surface.
Use airflow numbers only with the model and test condition they describe. Two units with the same filter-face dimensions can use different fans, motors, and filters. Confirm the voltage and replacement-filter part number for the exact unit you plan to buy.
Plan for the unit after delivery
Measure the bench, power outlet, and intake clearance. Leave room to move plates without putting them outside the filtered air stream. Decide where you will store the unit’s shipping pallet and how you will move the unit from curbside delivery into the room.
The prefilter takes the first load of room dust. Compare 20×20×1 in. MERV 11 replacements and 2×4 HEPA replacement filters by model and dimensions before buying spares.
Start your comparison in the equipment catalog. Each product page shows a dated listed price and the dimensions and delivery notes you need to check. “Buy now” opens an external checkout, where the final price and any freight charge are confirmed before payment.
