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How to Spec Avionics Enclosure Seals and Vents: What to Send H-O for a Quote
Avionics enclosure seals attract underspecified quote requests because the gasket looks like the whole story: a perimeter loop, a vent patch, a filter pad. What the quote actually prices is the duty behind it, the ingress severity, whether the box breathes, the closure force and lid stiffness, and how the gasket gets serviced. This is the ten-item checklist the H-O applications team works from, what engineering does with each item, and what comes back.
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The ten things to send, and what each decides
Avionics enclosure seals attract underspecified RFQs because the gasket looks like the whole story: a perimeter loop, a vent patch, a filter pad. What the quote actually prices is the duty behind it: the ingress severity, whether the box breathes, the closure force and lid stiffness, any RF or outgassing duty, and how the gasket gets serviced.
This is the ten-item checklist the H-O applications team works from for perimeter seals, vents, and filters, drawn from the parent application page's own selection factors, plus what engineering does with each item and what comes back.
| Send this | What it decides |
|---|---|
| 1. Ingress severity, named | The seal duty. Name the water, wash-down, condensation, or immersion, per the RTCA DO-160 sections and the IEC 60529 IP target, before sizing the seal. |
| 2. Altitude behavior: sealed or vented | Whether the box breathes. An altitude-cycled box needs an ePTFE vent so it does not pump in its own condensation. |
| 3. Closure force and lid stiffness | The CFD class and where it has to seat. A thin lid that bows needs a seal sized to the worst-case unsupported span, not the bolt line. |
| 4. Cell structure required | Closed-cell to seal, open-cell to filter. An open-cell pad at the seal line lets water in regardless of the IP target. |
| 5. RF or EMI duty | Whether the seal must also shield. A conductive seal per MIL-DTL-83528, or an RF-transparent seal at a radome, so the aperture does not attenuate its antenna. |
| 6. Outgassing and cleanliness | Per-grade ASTM E595 screening near optics and sensors, of the construction as built. |
| 7. Fluid exposure | A fuel- or hydraulic-adjacent bay moves the seal to fluorosilicone; it also sets where the vent must not go. |
| 8. Serviceability and kit scope | The gasket outlives nothing; design for the swap. Seal, vent, and filter can ship as one kitted part number. |
| 9. Geometry and presentation: DXF, STEP, or PDF | Perimeter profile, groove fit, connector pattern, vent and filter locations, and kiss-cut-on-liner format. |
| 10. Prototype and production volumes | Converting method and price structure. Every part is made to order; prototype quantities through production runs are equally accepted, and MOQ varies by material and part. |
What engineering does with the list
Items 1 through 4 set the seal and the breathing decision: a closed-cell BISCO RS or kSil V-0 perimeter seal sized to the lid span, a PORON thin-section seal for connector patterns, and a Gore ePTFE vent where item 2 says the box breathes. Item 5 adds the RF treatment, item 6 the low-outgassing grade screen, and item 7 the fluorosilicone redirect. Item 8 builds the kit, with a reticulated filter at the inlet. Items 9 and 10 become the converting plan and the price structure.
What happens after you send it
- Drawing review. Engineering reviews the box against the vendor TDS: ingress severity, altitude behavior, closure force and lid stiffness, cell structure, RF duty, outgassing, and fluid exposure.
- Material direction and quote. A family and grade direction with the TDS, the converted format (die-cut seal, vent patch, filter, kitted part number), and pricing at your quantities.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials we keep on hand.
- Production. Standard runs ship about two weeks after drawing approval, including kiss-cut-on-liner and seal-plus-vent-plus-filter kits; expedited service is available. Ongoing parts run with material traceability and lot-code TDS records.
Documentation available on request: material technical data sheet, certificate of conformance, and lot traceability, under our ISO 9001:2015 certified quality management system. H-O is a die-cut converter, not a raw-material producer: we do not manufacture the raw sponge, urethane, membrane, or foam, we do not independently certify them, and DO-160 qualification and ingress-rating certification belong to the box builder.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Fully sealed altitude-cycled box | Pumps in its own condensation | Item 2, sealed versus vented |
| Vent at a fluid-pooling low point | Wash fluid pushed against the vent | Items 2 and 7, vent placement |
| Seal sized to the bolt line | Thin lid bows and leaks midspan | Item 3, lid stiffness |
| Open-cell pad at the seal line | Water wicks straight in | Item 4, cell structure |
| Conductive seal in an antenna band | Aperture attenuates its antenna | Item 5, RF duty named |
| Family-level outgassing assumption | A sensor or lens fogs | Item 6, per-grade ASTM E595 |
Frequently asked questions
What information do I need to send H-O to quote an enclosure seal?
Ten items turn the gasket into a quotable drawing: the ingress severity named, the altitude behavior (sealed or vented), the closure force and lid stiffness, the cell structure required, any RF or EMI duty, the outgassing and cleanliness limits, the fluid exposure, the serviceability and kit scope, the geometry and presentation as DXF, STEP, or PDF, and the volumes. Send what you have; engineering frames the rest, including whether the box needs a vent, and flags any assumption.
Can H-O supply the gasket, vent, and filter as one kitted part number?
Yes, and it reduces the part count and the chance of a missing element at assembly. The closed-cell perimeter gasket, the ePTFE vent patch, and the reticulated inlet filter are different materials doing different jobs, so H-O die-cuts each correctly and laminates or kits them under one part number to the drawing. The seal blocks water, the membrane breathes, and the filter cleans the cooling air, shipped together with material traceability behind each element.
Does outgassing matter for avionics gaskets, and what is ASTM E595?
It matters wherever the gasket sits in or migrates toward an optics- or sensor-sensitive bay. ASTM E595 is the outgassing screen, reporting total mass loss and collected volatile condensable material per grade. Outgassing is a per-grade property, not a family trait, and the adhesive layers and liners a converter adds contribute their own, so the exact converted construction is screened against the program's limits per the E595 data. For a clean dry bay with no sensitive optics it is usually not a driver; near sensors it can decide the grade.
Can H-O cross-reference a DO-160 section or IP code on my drawing?
H-O cross-references the material, not the rating. If your drawing carries a DO-160 section, an IEC 60529 IP code, or a brand part number, engineering identifies a comparable sealing, venting, or filter grade from the lines we convert, matching on CFD class per ASTM D1056, set per ASTM D395, outgassing per ASTM E595, and the ingress and RF behavior the box requires, and converts it to your geometry. Demonstrating the DO-160 section or the IP rating on the finished box is the box builder's, verified on the assembled enclosure.
What lead time should I expect for enclosure-seal samples and production?
Every enclosure seal, vent, and filter is made to order, including samples. Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand; standard production runs ship about two weeks after drawing approval, including kiss-cut-on-liner and seal-plus-vent-plus-filter kits; expedited service is available when timing is critical. MOQ varies by material and part, and prototype quantities through production runs are equally accepted.
Send the checklist, get an enclosure seal quote
Attach the geometry and as many of the ten items as you have. If something is unknown, say so; the review proceeds with the assumption flagged.
Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand; standard production runs about two weeks after drawing approval; expedited service is available. MOQ varies by material and part.
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Related reading
Request a quote for your avionics enclosure sealing part
Send H-O your drawing or describe the part—engineering reviews every RFQ and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- RTCA DO-160 (airborne environmental and ingress framing, cited qualitatively; qualification belongs to the box builder).
- IEC 60529 (the IP ingress-protection code, cited qualitatively).
- ASTM D1056 (compression-force-deflection classes); ASTM D395 (compression set); ASTM E595 (outgassing, per grade).
- UL 94 (flammability listings); MIL-DTL-83528 (conductive elastomer framing where the seal must shield, by designation).
- Manufacturer technical data sheets for the silicone sponge, microcellular urethane, solid silicone, fluorosilicone, ePTFE membrane and sheet, and reticulated filter foam named on the parent application page.
This article summarizes enclosure sealing and venting material-selection principles for avionics and electronics using the families and published test methods cited on the parent application page. Comparisons are qualitative; per-grade values quoted are maker-TDS figures and must be confirmed on the manufacturer's current technical data sheet at your closure force, altitude, and installed condition. Standards (RTCA DO-160, IEC, ASTM, UL, MIL-DTL) are cited by designation for context, not as a claim of qualification.
H-O is a precision die-cut converter, not a raw-material producer, and does not qualify enclosures to DO-160, certify ingress ratings, or hold platform certifications; those belong to the box builder and its test houses.