Shielded Air Vent Honeycomb Filters

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Designed to provide consistent and reliably high levels of shielding while allowing cooling air to penetrate an electrical equipment.

Spira’s Patented Process

All Spira-Cell Air Vent Filters include our patented “blending” process of the aluminum honeycomb panel that provides high and reliable levels of shielding. Our filters also include the use of epoxy which mechanically bonds the honeycomb panel to the frame and the use of our patented spiral EMI gasket, which ensures an excellent, long-lasting EM bond between the panel and the frame.


Honeycomb Filter Options and Shielding
Type of FilterPanel & Frame OptionsPanel Thickness
Spira-Cell • Gasket inside Frame1 Aluminum Panel60dB80dB80dB--
2 Aluminum Panels (Tin Plated Frame)110dB130dB----
Spira-Cell, Salt-Fog1 Aluminum Panel (Tin Plated Frame & Panel)60dB80dB80dB--
2 Aluminum Panels (Tin Plated Frame & Panel)110dB130dB----
  TIn Plated Frame & Panel
Spira-Cell, “Light” Salt-Fog1 Aluminum Panel (Chem-Film Frame & Panel)60dB80dB80dB--
2 Aluminum Panels (Chem-Film Frame & Panel)90dB90dB----
  Chem-Film Frame & Panel
Brass-Cell1 Brass Panel (Tin Plated Frame)--110dB130dB140dB
Brass-Cell, Salt-Fog1 Brass Panel (Tin Plated Frame & Panel)--110dB130dB140dB

Note: The shielding specified (in dB) is typical of the data we have obtained. Results may vary depending on application.

W = Honeycomb panel cell width = 1/8” standard. Other cell sizes are available through special order.
T = Panel Thickness as shown above. The filter thickness will double for 2 panel configurations.

Custom and RoHS compliant Honeycomb Filters are available on request. Contact us for more information.

Design Advantages (All Types)

Due to their construction and materials, our honeycomb filters offer several cost-effective advantages over the other honeycomb filters on the market.

Competitive Cost

A fully automated machine is used to cut the frame to size. This machine is coupled with several automated and semi-automated processes used to apply epoxy to the frame/honeycomb panel interface for mechanical strength of the filter, and to install the electromagnetic (EM) bonding spiral gasket to the extrusion. These machines and processes significantly reduce the time required to manufacture and assemble the filters, and we pass that savings on to our customers.

Shielding Advantage

The honeycomb panels we use offer high, reliable levels of shielding. The Brass-Cell uses brass foils soldered together which provide extremely high, reliable shielding. The aluminum panels used for Spira-Cell filters are processed using our patented blending process that ensures a reliable conductive path across the epoxy joints of the honeycomb cells. Tests have shown as much as a 40 dB improvement for single panel filters and 70 dB improvement for double panel filters over the use of panel material which has not been processed. See pages 29 and 32 for complete performance data.

Reliable Joint Surfaces

We use 6061 aluminum for our frame members because of its high surface conductivity and corrosion resistant properties. We augment this with tin or tin/lead plating (when specified) to meet higher levels of shielding and/or corrosion compatibility requirements. Chemical film plating can also be employed when the high levels of shielding associated with tin plating are not required. Any plating is done prior to assembly which guarantees that the acids and other chemicals used in the pre-plating etch process are totally removed from the components, thus ensuring a long, reliable life of the filter.

Spiral Bonding

Spira EMI gasket materials are used to obtain an excellent, reliable frame-to-chassis bond on all types of filters. The gaskets are also employed for the honeycomb panel-to-frame electromagnetic bond on the Spira-Cell and Brass-Cell filters. The spiral gaskets are employed for the purpose of absorbing thermal expansion and contraction, shock, and vibration to insure an excellent electromagnetic bond throughout the life of the filter.

Frame Style

The honeycomb panel frames are used to hold the honeycomb panel material in place and to reference the honeycomb panels to equipment chassis ground potential. The frame comes with a spiral EMI gasket for panel bonding on either Spira-Cell or Brass-Cell filters.

Spiral-Bonding Frame

The extrusions used for the Spira-Cell and Brass-Cell filters have built-in dovetail grooves. These grooves are used to hold the spiral EM bonding gasket in place during the manufacturing process and allow the gasket to move unrestricted during compressed applications. This unrestricted movement allows the gasket to absorb movement of the joint surfaces during thermal expansion and contraction, vibration and shock. This results in reliable EM bonding between the honeycomb panel and the frame throughout the life of the filter.

Cell Width

All of the standard filters use a 1/8” cell. Other cell sizes are available through special order. Contact us for availability.

Cell Thickness

The standard panel thicknesses are 1/8” (Aluminum only), 1/4”, 1/2” or 1”. Contact us for availability.

Threaded Inserts

Filters can be made either with through holes of varying sizes or fitted with threaded inserts. For cost efficiency, we recommend even spacing of holes. Threaded inserts are not available on the 1/8” thick panels.

The high humidity/salt spray versions use our edge tin/lead plated beryllium copper gaskets and are available in the following configurations:


Spira-Cell: Tin plated aluminum frame and honeycomb panel (or chem-film plated for “light” salt-fog)
Brass-Cell: Tin plated brass honeycomb panel with tin plated aluminum frame
RoHS compliant versions also available on request.

Static Pressure Drop Versus Air Speed

To Order

All honeycomb filters are made-to-order to your specifications. Please send a drawing that specifies the following information:

  1. Size of Filter: Length and Width
  2. Type of Honeycomb Panel: Aluminum or Brass
  3. Thickness of Honeycomb Panel: 1/8” (Aluminum only), 1/4”, 1/2 ”, or 1” (brass only)
  4. Number of Honeycomb Panels: One or Two Panels
  5. Plating and Environmental Concerns: No Plating, Salt-Fog, or Max Shielding (specify RoHS if needed)
  6. Outside Spiral Selection: Spira-shield (standard); or optional Flexi-Shield adds extra protection for the spiral gasket during handling
  7. Mounting Hole Information:
    • Quantity of Holes
    • Location of Holes
    • Through Holes or Threaded Inserts
    • Hole or Thread Size

Honeycomb Filter Specifications

Standard tolerances are:
    XX ± .03
 XXX ± .015
unless noted otherwise.
All dimensions in inches.






Single panel Spira-Cell or Brass-Cell with through holes

Single panel Spira-Cell or Brass-Cell with threaded inserts

Double panel Spira-Cell with through holes

Made In Usa