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How to Spec a Thermal-Runaway or Fire-Protection Barrier: What to Send H-O for a Quote
A barrier RFQ is different from a gasket RFQ in one important way: the material cannot be named until the job is split. "Thermal barrier, 1 mm, per the attached DXF" could be an aerogel isolation layer, a mica vent shield, a laminated propagation barrier, or a cushioning foam with flame duty, and each is a different part with a different price.
The H-O applications team works from the ten-item checklist below, taken from the parent application page's own what-to-send list. Send it complete and the first reply is a family direction, a ply construction if the job needs one, and a quote.
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The ten things to send, and what each decides
| Send this | What it decides |
|---|---|
| 1. Barrier location in the pack | Cell-to-cell, module wall, vent path, busbar zone, or compartment liner. Location sets the duty profile and the geometry constraints before any material talk. |
| 2. The job: isolation, flame, or both | The fundamental split. Conduction-slowing and flame-and-ejecta survival are different physics; "both" usually means a laminated construction rather than one material. |
| 3. Available thickness / gap | The hardest constraint in most packs. Thin gaps push toward aerogel; generous gaps open more options; no material can be chosen without it. |
| 4. Compression range (if a cell gap) | A compressible barrier performs at its in-service compressed thickness, which moves as cells breathe and swell, so the range belongs on the drawing, not in a follow-up email. |
| 5. Temperature exposure | Continuous service temperature and the event exposure are different numbers; the second decides the flame-face ply, the first the everyday materials. |
| 6. Any electrical-isolation role | If the barrier also isolates a busbar or terminal, the dielectric requirement is verified separately per grade; it is never assumed from the thermal role. |
| 7. Propagation / flammability method | Which method governs your assembly (UL 9540A, GB 38031, UL 2596-type material behavior, UL 94 class), so candidate constructions are compared against the right yardstick. |
| 8. Barrier footprint and cut-outs | The converting plan: die-cut, kiss-cut, laser, or waterjet, and how the cut-outs and edges interact with friable layers. |
| 9. Facing / encapsulation needs | Aerogel and some inorganic papers shed when cut; a facing film, edge encapsulation, or capture lamination keeps the line clean. Cleanliness requirements belong here. |
| 10. Prototype and annual volume | Method and price structure; prototype quantities through production runs are equally accepted. |
What engineering does with the list
Items 1 through 3 sort the family shortlist: aerogel blanket for thin-gap conduction, EV firewall barrier sheet (and the broader thermal and fire barrier constructions) where propagation governs, mica barrier sheet where very high temperature meets an electrical role, glass-fiber paper as the thin inorganic ply, and high-temperature silicone foam where the layer must also cushion.
Items 4 and 5 check the shortlist against the real duty (compressed thickness, continuous versus event temperature). Item 6 routes any dielectric duty to the grade's electrical data.
Item 7 selects the comparison method, with the honest boundary stated every time: material-level behavior comes from the manufacturer's data sheet under methods like UL 2596 and UL 94, and assembly-level outcomes under UL 9540A or GB 38031 belong to your tested pack.
Items 8 through 10 set the converting plan, including facing and encapsulation for friable layers and lamination where the answer is a multi-ply construction supplied as one part.
What happens after you send it
- Drawing review. Typically opened the same business day; the reply is a family or construction direction, or the specific missing items.
- Construction proposal and quote. Family and grade direction (or a ply stack with each layer's job named), converting method, facing and encapsulation plan, and pricing at your quantities, with grade data cited to the manufacturer's TDS.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials on hand; laminated constructions are quoted with their own sample timing.
- Production. Standard production runs about two weeks after drawing approval; special orders are quoted to the job. MOQ varies by material and part.
Documentation available on request: material technical data sheets for every ply, certificate of conformance, lot traceability, and first-article inspection, under our ISO 9001:2015 certified quality management system. H-O is a die-cut converter, not a raw-material producer: we do not make the aerogel, mica, paper, sheet, or foam, and we do not certify a material to UL 9540A or GB 38031; no pass or number is claimed.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| "Thermal barrier" with no job split | An insulator on a vent path, or a flame sheet asked to insulate | Item 2 |
| Free-thickness data on a compressed layer | In-service performance differs from the bench value | Items 3 and 4 |
| Event temperature used as service temperature | Everyday materials over-specified; cost without benefit | Item 5 |
| Dielectric duty discovered at validation | A flame-qualified part that fails an electrical check | Item 6 |
| Friable layer cut bare | Dust on the battery line; cleanliness rejections | Item 9 |
| Propagation "pass" expected from a material | A claim no raw material can carry; assembly testing surprised | Item 7, with the boundary stated |
Frequently asked questions
Can H-O recommend a barrier without the cell format and event details?
We can narrow the family from location, job, gap, and temperature, which is most of the way. But cell format and the governing method matter for the construction (a pouch stack's breathing range changes the compliant ply; a propagation requirement changes the core), so the recommendation is provisional until those arrive. The reply will say exactly which items the direction is waiting on.
How are friable materials like aerogel handled on the drawing?
Call out the cleanliness requirement and let the converting plan answer it: a facing film on one or both sides, edge encapsulation after cutting, or lamination that captures the friable core between cleaner skins. These are normal converting operations at H-O, specified per the manufacturer's allowances for the grade, and they should appear on the drawing as part of the part, not as a line-side workaround.
What if my barrier needs to satisfy two methods at once?
List both in item 7. A vent shield might be compared under UL 2596-type behavior while the pack pursues GB 38031 propagation compliance; a cell-to-cell layer might carry a UL 94 class while supporting a UL 9540A program. Material-level behavior and assembly-level outcomes live at different levels, and naming both up front keeps the candidate comparison honest.
Does a laminated construction cost more than a single material?
It depends on the alternative. A laminate has more plies and a lamination step, but it usually replaces a thicker, more expensive single material that still would not do both jobs, and it is supplied as one die-cut part with no extra line labor. Send the volumes in item 10 and the quote will show the comparison at your quantities rather than in the abstract.
Send the checklist, get a barrier quote
Attach the footprint and as many of the ten items as you have. Drawing review typically starts the same business day.
Samples typically 3 to 5 business days; production about two weeks; MOQ varies by material and part. Expedited service available.
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Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- UL 2596 (battery enclosure material behavior under flame with entrained particles); UL 94 (flammability classifications).
- UL 9540A and GB 38031 (assembly-level propagation methods); UN 38.3 (transport, pack level); ASTM E162 / E662 (flammability and smoke characterization).
- Manufacturer technical data sheets: aerogel blanket, EV firewall barrier sheet, mica barrier sheet, glass-fiber paper, high-temperature silicone foam.
This checklist supports a quotation workflow; it does not constitute design guidance for any specific pack. Grade-level behavior is confirmed on the manufacturer's current technical data sheet at your thickness and compression; propagation outcomes belong to the tested cell, module, pack, or system. All parts are custom manufactured to order; minimum production run quantities vary by material and part. H-O is a die-cut converter, not a raw-material producer.