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Filter Bag Information

Explanation of Filter Bag Sizes, Efficiency, and Sealing Terminology

The size and type of filter bag determine the design of the corresponding bag filter vessel—specifically how it interfaces/seals with the vessel and the number of chambers required to handle your flow rate.

Filter Bag Sizes and Capacities

The most common filter bag sizes are generically referred to as #1, #2, #3, or #4. Their dimensions and maximum water-like fluid capacities for nominally rated bags are shown in the table below.

Filter bag specifications chart

†Capacity depends upon the vessel inlet size and the maximum recommended flow velocity of 12 FPS.

In addition to these industry standards, we offer brand-specific designs such as Ronningen-Petter Certa-Seal and SE series, as well as 152 and 154 series filter bags. Maximum capacity is always subject to the retention level of the bag and maintaining an inlet velocity ≤12 FPS.

Retention and Efficiency

Retention is expressed in microns (μm); divide by 1000 to convert to millimeters (mm).

Filter Bag particle retention

Efficiency: Eaton filter bags are offered in two primary efficiencies:

  • Nominal: Approximately 65% efficient for the stated particle size when clean. As particles are trapped, efficiency increases. For example, a 1μm nominal bag is 65% efficient for ≥1μm, but 99% efficient for particles >25μm.
  • 99% or "Absolute": Retains 99% of all particles at or above the stated micron rating.

Higher efficiencies are achieved using thicker materials or multiple layers, creating a tortuous path to maximize particle loading volume.

Filter Bag Seals

Proper sealing prevents bypass, ensuring all fluid passes through the media.

SNAP-RING filter bag seal

SNAP-RING™: These economy bags use a metal or plastic ring sewn into the opening that "snaps" into the housing's support basket groove. Available in stainless steel, carbon steel, polypropylene, and nylon.

SENTINEL RING filter bag sealing ring

SENTINEL™ RING: A molded plastic ring welded to the bag. Its unique shape creates a "crush seal" under pressure, forcing the bag material against the support basket for a tighter seal. These often require a "hold down ring" to transfer lid pressure, though TOPLINE™ housings do not require one.

Restrainer Baskets

filter bag restrainer basket

Restrainer baskets provide structural support to a filled filter bag, preventing damage under pressure. Standard baskets are 316SS with 9/64" (3.57mm) perforations.

Strainer Conversion: We can provide mesh-lined baskets (from 20 to 325 mesh) to convert your filter housing into a permanent strainer, eliminating the need for disposable bags in certain applications.

Filtering something other than water-like liquids? We can calculate the clean differential pressure for different viscosities to help you choose the right bag and housing size. Call 908.362.9981 or use our inquiry forms for expert support.