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Spira’s Shielded Air Vent Honeycomb Filters are designed to provide consistent and reliably high levels of shielding while allowing cooling air to penetrate an electrical equipment cabinet.They include the “Spira Advantage”, using our patented honeycomb blending process and patented spiral gasket to provide exceptional EMI shielding and EM bond. There are three types of air vent filters to choose from for different levels of shielding: Econo-Cell; Spira-Cell; and Brass-Cell. See below for ordering information. Also note that Spira has a NEW Shielded Honeycomb Fan Filter.

Design Advantages
(All Types)

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 the Econo-Cell and 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. Refer to Shielding Quality 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.

Available Options (All Types)  

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 in two basic styles. These are: knife-edge panel bonding (for the Econo-Cell filter); and spiral EMI gasket panel bonding (for the Spira-Cell and Brass-Cell filters).

"C" Frame Knife Edge Bonding The "knife" edge supplies shielding at an affordable price.

"C" Frame Spiral Bonding Dovetail groove holds gasket in place during manufacture.

Knife-Edge Frame:
The extrusion used for the Econo-Cell filter has a single knife edge at the top of the extrusion for the single-panel filter and a knife edge on both the top and bottom for the double-panel filter. This extrusion shape has limited life characteristics and is only recommended for extremely cost-sensitive applications.

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 illustrated in Table 1. The configurations offered are designed to optimize the shielding versus cost. Other configurations are available by special order. 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.

Spira-Cell:
The Spira-Cell filter is a high reliability air vent filter supplying moderate to high levels of shielding at a relatively low cost. It features an EMI gasket to achieve the honeycomb panel-to-frame EM bond. It comes in both single and double panel configurations with a 6061-T4 aluminum frame and stainless steel gasket (Quick-Shield) or tin plated frame with tin plated stainless steel gasket (Ultra Quick-Shield) for the EM bond between the panel and frame and frame-to-chassis.
A version is also available for high humidity and salt spray environments.

Brass-Cell:
The Brass-Cell filter gets its name by using brass honeycomb panels. The brass foil is soldered together ensuring consistent, reliable shielding of the filter. The filter offers a reliable, high level of shielding at a relatively low cost. The Brass-Cell filter consists of a tin plated aluminum frame, tin plated stainless steel gasket (Ultra Quick-Shield) and brass honeycomb panels. The filter is designed to operate in a relatively low humidity environment due to potential material incompatibilities. A version is also available for high humidity and salt spray environments.

Salt-Fog:
The high humidity/salt spray versions use our edge tin/lead plated beryllium copper gasket (Spira-Shield) and are available in the following configurations:

Spira-Cell: Tin plated or chem-film plated aluminum frame and honeycomb panel.
Brass-Cell: Tin plated brass honeycomb panel with tin plated aluminum frame.

Refer to Material Specifications & Compatibility for more information.

Shielding Effectiveness
The shielding effectiveness testing of Spira’s honeycomb filters is performed by generating an electromagnetic field through a hole in an enclosure and recording the field strength. The honeycomb filter under test is then attached to the enclosure and a second field strength measurement is recorded. The shielding effectiveness is the difference in the recorded field strength readings in dB.

Shielding Effectiveness of Econo-Cell Filters

1. Threshold Test Limit 2. Econo-Cell, 2 panel, 1/8” wide x 1/8” deep 3. Econo-Cell, 1 panel, 1/8” wide x 1/8” deep 1. Threshold Test Limit 2. Brass-Cell, 1/8” cell x 1“ deep 3. Brass-Cell, 1/8” cell x 1/2“ deep; Spira-Cell, 2 panel, 1/8” cell x 1/4“ deep 4. Brass-Cell, 1/8” cell x 1/4“ deep; Spira-Cell, 2 panel, 1/8” cell x 1/8“ deep 5. Spira-Cell, 1/8” cell x 1/4“ deep

Static Pressure Drop Versus Air Speed  
 

1)  1/8" x 1/8" aluminum 2)  1/8" x 1/4" aluminum 3)  2 panel 1/8" x 1/8" aluminum & Brass Cell  1/8" x 1/4"  4)  2 panel  1/8" x 1/4" aluminum & Brass Cell  1/8" x 1/2" 5)  Brass Cell  1/8" x  1"

Air-Vent Honeycomb Filter Matrix

Table 1 Type of Filter Panel T=1/8" Panel T=1/4" Panel T=1/2" Panel T=1" Econo-Cell • Knife Edge Frame • Tin-plated Frame 1 Panel 2 Panel 2 Panel Tin-plated HF-EC12-1 60dB HF-EC22-1 90dB HF-TEC22-1 110dB HF-EC12-2 80dB HF-EC22-2 90dB HF-TEC22-2 130dB HF-EC12-4 80dB -- -- -- -- -- Spira-Cell • Gasket Inside   Frame • Tin-plated Frame   Option 1 Panel 2 Panel Tin-plated HF-SC12-1 60dB HF-TSC22-1 110dB HF-SC12-2 80dB HF-TSC22-2 130dB HF-SC12-4 80dB -- -- -- Brass-Cell • Tin-plated Frame 1 Panel Brass -- HF-BC12-2 110dB HF-BC12-4 130dB HF-BC12-8 140dB Salt-Fog Option • Spira-Cell Salt Fog • Tin or Chem-Film   plated Frame &   Panel 1 Panel Tin-plated 2 Panel Tin-plated 1 Panel Chem-film 2 Panel Chem-film HF-TTSC12-1 80dB HF-TTSC22-1 110dB HF-CSC12-1 60dB HF-CSC22-1 90dB HF-TTSC12-2 80dB HF-TTSC22-2 130dB HF-CSC12-2 80dB HF-CSC22-2 90dB HF-TTSC12-4 80dB -- HF-CSC12-4 80dB -- -- -- -- -- • Brass-Cell Salt-Fog • Tin-plated Frame &   Panel 1 Panel Tin-plated -- HF-TBC12-2 110dB HF-TBC12-4 130dB HF-TBC12-8 140dB
	Note: The shielding specified (in dB) is typical of the data we have obtained. Results may vary depending onapplication. W = Honeycomb panel cell width = 1/8" standard. T = Panel Thickness as shown above. Other cell sizes are available through special order.
Table 2 Standard Hole Sizes Standard Threaded Insert Sizes .120" 4-40 .147" 6-32 .173" 8-32 .204" 10-24

Ordering Information

To order, please send us a drawing that specifies the following information:

• Spira Honeycomb Filter part number from matrix (see Table 1 )
• Size of filter: length and width
• Number of holes and hole placement
• Type of holes: Through holes, threaded inserts or counter-sinks (see Table 2 )

Honeycomb Filter Specifications

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