Size 3 is the small-housing standard: 4″ diameter × 8″ long with a pointed bottom, about half a square foot of media, sized for roughly 25 GPM. It shows up on pilot systems, small batch processes, point-of-use polishing, and sample loops — anywhere a full-size housing would be overkill.
Size 3 Specifications
| Attribute | Detail |
|---|---|
| Diameter | 4″ |
| Length | 8″ |
| Surface area | ~0.5 ft² |
| Typical max flow | ~25 GPM (clean water; derate per the sizing guide) |
| Bottom style | Point (conical) |
| Media | Felt 1–200 µm, mesh 35–800 µm; FDA grades available |
| Construction | Sewn (welded available for specialty applications) |
| Top options | Steel, stainless, polypropylene or nylon ring; drawstring; open |
Fits
Size 3 bags fit standard #3 (4×8) housings from the major manufacturers. Sizes 3 and 4 share the same 4″ ring — measure bag length to tell them apart: 8″ is a 3, 14″ is a 4.
Small Bags, Small Batches
Size 3 is also a favorite for lab and pilot work that will later scale to size 1 or 2 — same media, same micron, so filtration results transfer directly. We stock the same media range across all four sizes for exactly that reason.
Ordering size 3 bags? Call 800-554-8555 or request a quote.