FIRE SLEEVE & HEAT SHIELD
Four constructions for harness protection near heat sources: aluminium-foil fibreglass tubing (flat, tight to the bundle), aluminium-foil corrugated fibreglass tubing (corrugation for routing), self-adhesive fire sleeve (retrofit without disconnecting wires), and high-temperature fibreglass fire sleeve without a reflective layer (material-based insulation).
Product structures
Aluminium foil bonded over a fibreglass substrate, smooth surface. The foil does not provide temperature resistance — it reflects radiant heat back, which is why it performs best directly facing the source. Flat construction sits close to the bundle and suits tight, mostly straight runs.
Same foil + fibreglass composite with a corrugated wall. Corrugation prevents creasing when bending and creates an interrupted air gap between wall and harness. The trade-off is a larger OD at the same ID and a slightly higher unit price.
Fibreglass substrate with aluminium-foil reflective layer (some constructions add a silicone coating) and a hook-and-loop closure. Fits without disconnecting wires — for retrofit and service sections. Continuous rating 260 °C or 300 °C depending on construction grade; 1000 °C is a seconds-level flame-impingement reference, not a continuous rating.
Braided fibreglass without foil. Insulation comes from the material's low conductivity and thickness rather than reflection — appropriate where the sleeve contacts high temperature directly or must survive short flame impingement.
Selection
Insulation performance depends on four things, not just the temperature rating: heat source type, distance to the source, whether the ends are closed, and the presence of oil or coolant. An open-ended sleeve allows hot air into the bore and can run 30%+ hotter internally than a closed section.
Structure comparison
Temperature values are reference ranges; the selected specification governs.
| Structure | Mechanism | Temperature (reference) | Bend adaptability | Retrofit | Abrasion | Typical position |
|---|---|---|---|---|---|---|
| Foil fibreglass tube (flat) | Foil reflection + fibreglass | Substrate-dependent | Low (creases) | Thread-through | Low (foil wears through) | Straight runs facing radiant heat |
| Foil corrugated tube | Reflection + air gap | Substrate-dependent | High | Thread-through | Low | Multiple turns, bend radius below 3× ID |
| Self-adhesive fire sleeve | Foil reflection + fibreglass | 260 °C / 300 °C continuous; 1000 °C surge reference | Medium | High (hook-and-loop) | Medium | Engine bay, retrofit and service sections |
| Fibreglass fire sleeve (no foil) | Low conductivity + thickness | To 600 °C continuous; higher short-term | Medium | Thread-through | High | Direct high-temperature contact, short flame |
The self-adhesive sleeve is available in both 260 °C and 300 °C continuous grades — state the grade required when enquiring.
The 1000 °C figure applies to seconds-level flame impingement and is not a continuous rating; it does not constitute a commitment for every specification.
Wall thickness
The foil composite thickness scales with the wall-thickness grade, not only the ID: larger diameters and heavier walls carry a thicker composite to withstand assembly stress, while fine diameters prioritise conformity. Two sleeves with the same 10 mm ID can behave very differently in insulation and bendability.
Quoting a bare ID therefore compares different products — which is why apparently identical sleeves can differ twofold in price. Specify ID plus wall thickness (or OD) and ask for the wall thickness on the quotation.
Layering
Where radiation is intense and the sleeve sits close to the source, layer instead of thickening: reflective tubing on the inner run with a fibreglass sleeve over it, using the trapped air gap for additional insulation. Both are standard products, so this needs no special construction or tooling.
Installation pitfalls
The continuous rating is 260 °C or 300 °C by grade — nearly a factor of four lower. Designing to the surge value ages and delaminates the composite early, usually in the section closest to the source.
The foil is thin; abrasion against brackets removes the reflective layer and insulation drops to zero. Any rubbing position needs a braid or coating outside.
Initial tack is highly sensitive to surface cleanliness. Clean and press firmly before installation; add ties where needed.
Open ends let hot air into the bore — the most common reason a shielded harness still exceeds its limit. Wrap in sections and overlap between them.
Compressing the air gap removes part of the insulation. Keep the sleeve in contact but not stretched; preserve the corrugation.
The foil creases and the crease is where reflection fails first; loose foil fragments can migrate into connectors. Use corrugated tubing or straight sections with elbow transitions.
FAQ
Not exactly. Fire protection focuses on flame integrity under short impingement; heat shielding focuses on reducing internal temperature rise. The self-adhesive sleeve covers both to a degree; for intense radiation at close distance, layer reflective and fibreglass sleeves rather than thickening one.
Flat where the run is essentially straight and space is tight — smaller OD, tighter fit, lower unit price. Corrugated where the harness turns or the bend radius falls below roughly 3× the ID.
260 °C or 300 °C continuous, depending on construction grade; both are produced. The 1000 °C figure is a seconds-level flame-impingement reference and must not be used as a continuous rating.
Because the products differ. Cost is driven by wall-thickness grade, foil composite structure and fibreglass basis weight — none of which appear when only the ID is quoted. Specify ID plus wall thickness or OD, and require the wall thickness on the quotation.
RFQ
Routing and heat-source conditions settle the construction in one pass:
Related products
Samples and selection
Include heat source type and distance, continuous and peak temperature, bend situation, retrofit requirement, ID and wall grade, expected volume.
