Round Pocket Filter Box for Air Ducts

A round pocket filter box (inline pocket filter housing) is a high-efficiency deep purification component designed for supply, extract, and recirculation ventilation systems. Installed directly into round duct runs, this unit serves as an advanced defensive barrier against atmospheric pollution. The defining engineering characteristic of this model is its multi-pocket cloth filter configuration. Due to an extended three-dimensional surface area, pocket type filters deliver a significantly higher dust-holding capacity compared to flat cassette variants. This allows the housing to modulate indoor air quality across a broad filtration spectrum—ranging from capturing coarse outdoor debris like sand and road dust to capturing microscopic allergens, spores, pollen, and bacteria.

The robust rectangular enclosure is manufactured on automated industrial machinery from long-lasting hot-dip galvanized sheet steel, grade DX51D, carrying a dense protective zinc passivation mass of Z275 (275 g/m²). This selection of raw materials offers exceptional mechanical rigidity against static airflow pressure and completely prevents rust formation. Integrating a pocket filter housing into the ventilation line safely blocks airborne particulate accumulation on expensive downstream HVAC assets—such as inline fans, electric heaters, and heat recovery cores—extending system service intervals and reducing maintenance budgets.

Key Benefits of the Pocket Filter Box

• Extended service lifespan and lower operational costs: The large surface area of the multi-pocket filter media ensures a very gradual increase in aerodynamic resistance as dust accumulates. This allows the inner element to operate efficiently for much longer periods without forcing a drop in total fan airflow performance, reducing the frequency of replacement media purchases.
• Tool-free inspection cover for immediate servicing: The top-access maintenance hatch is secured with convenient ergonomic threaded wing nuts. This setup permits mechanical operators or property owners to rapidly extract a soiled pocket filter and slide in a clean element entirely by hand, eliminating the hassle of sourcing specialized screwdrivers or wrenches.
• System versatility with scalable air purification classes: Precision-fit internal guide tracks allow building operators to flexibly adjust air cleanliness parameters according to changing environmental demands. The exact same housing can alternately accommodate basic coarse pre-filter bags or high-density fine filtration pockets without requiring housing replacements.
• Airtight joint locking to prevent pressure losses: The circular connection ports feature pre-installed double-lipped EPDM rubber gaskets. These elastic rings establish a reliable friction fit inside straight duct lines, minimizing static pressure leaks at connection joints and discarding the need for liquid mastics, silicones, or exterior duct tapes.

Technical Specifications and Dimensional Matrix

The structural configurations, linear dimensional data, and collar manufacturing tolerances fully comply with European engineering standards CE, EN 1505:2000, and EN 1506:2007 for round sheet metal air ventilation ducting. The double male connection collars are engineered for clean inline sliding inside standard air pipes.

• Housing Base Material: High-grade galvanized sheet steel DX51D (Z275 zinc passivation layer)
• Metal Thickness Range: 0.5 mm to 1.0 mm proportional to the nominal enclosure scale
• Operational Environment Parameters: Stable performance within a temperature range of -40°C to +70°C
• Recommended Replacement Interval: Media swap-out is advised upon reaching a final pressure drop between 250 and 450 Pa
• Connection Collar Interface: Double male nipple profile with factory-pressed EPDM gaskets

Assembly, Positioning, and Maintenance Guidelines

Position the pocket filter box at the initial stage of the air supply run, downstream of the external intake louver but upstream of the ventilation fan or heater unit. Slide the male connection ports directly inside straight round ducts until they hit the pre-rolled physical stop beads, then mechanically secure the overlapping joint using blind rivets or self-tapping screws. When selecting the installation site, it is critical to provide sufficient clear space on the side of the removable service cover to ensure the unhindered withdrawal of the long fabric filter pockets. Wrap all outer connection seams with high-adhesion aluminum tape to verify compliance with the design channel tightness class.