Aluminized vs Silicone Fire Sleeve: Which One?
Two products are sold under one name and they stop different things. An aluminized sleeve reflects radiant heat across a gap. A silicone-coated fiberglass sleeve takes flame, spatter and abrasion on contact. Fitting the wrong one is the most common fire sleeve mistake we see in enquiries.
What each sleeve actually does
Radiant heat travels in a straight line from a hot surface. A bright aluminium face has low emissivity, so across an air gap it bounces that radiation back toward the source instead of absorbing it. Aluminum foil fiberglass fire pipe is built for that duty. The foil is the reflector, a fiberglass core carries the body and the conducted heat load, and a fire resistant layer holds the core together under flame contact.
Flame impingement, molten spatter and abrasion are a different problem, and reflection does nothing for them. Silicone coated fiberglass sleeving answers those. It is a woven glass wall with a cured silicone outer face, rated -60°C to +200°C, slip on and non-shrink.
One detail follows from the construction: the foil face is metal. Reflection is the outer face doing its job, and that same face is electrically conductive. It also stops working the moment the gap closes, because contact transfers heat by conduction and the foil cannot block that.
Side by side
| Aluminized foil sleeve | Silicone-coated fiberglass sleeve | |
|---|---|---|
| Primary duty | Radiant heat reflection | Flame, spatter, abrasion |
| Needs an air gap | Yes. Reflection collapses on contact | No |
| Electrically conductive | Yes, the face is aluminium | No |
| On direct contact | Loads by conduction, foil cannot block it | Tolerates contact within its rating |
| Face behaviour | Foil scuffs, dents and dulls | Silicone face resists wipe down and wear |
| Published rating | Continuous value under verification | -60°C to +200°C |
| Typical position | Exhaust runs and hot pipework with clearance | Motor leads, engine bay looms, welding areas |
How to choose in four checks
- Name the heat mechanism first. Radiant with clearance points to a foil build. Contact, flame or spatter points to a coated build.
- Check the conductive question. If the sleeve crosses or sits near live conductors, confirm how the design isolates the foil face.
- Confirm the surface temperature at the hottest point and compare it with the published rating for the build.
- Keep or lose the gap. Foil duty needs clearance. Where contact is unavoidable, treat the position as conductive duty and re-check the choice.
Two things buyers get wrong
The first is reading an aluminized sleeve as electrical insulation. Aluminium is a metal and the foil face conducts, which matters whenever the run passes a live conductor. That question has its own guide: is aluminum foil fire sleeve conductive.
The second is trusting a single temperature number. The catalogue figure of 1000°C short term is on hold on our own product page until its test basis is published. Aluminium melts near 660°C, so any figure above that describes one test geometry rather than a working contact rating. Ask what a number measures before you design to it.
What to send for a sized recommendation
State the heat source and the duty: radiant with a gap, or contact and flame. Give the pipe or bundle OD, the length with bend allowance, the environment, and whether the run passes live conductors. Send those and we size the sleeve.
Frequently asked questions
Can an aluminized sleeve sit directly on a hot pipe?
It can be fitted, but contact is conductive duty, not radiant duty. The foil only reflects across a gap. Once it touches the line the load arrives by conduction and the fiberglass core has to carry it.
Which one lasts longer?
They fail for different reasons. A foil face dulls, scuffs and oxidises, which lowers reflection. A silicone-coated wall fails by coating wear or cut through. Match the likely failure to what your route does.
Is aluminized fire sleeve electrically conductive?
Yes. The foil is aluminium, a metal. Treat the outer face as conductive and keep it clear of live conductors unless the design provides the isolation.
Can silicone-coated sleeving go on an exhaust manifold?
It tolerates contact better than foil, so check the hottest surface temperature against the -60°C to +200°C rating. Above that, change the build or restore an air gap with a reflective sleeve.
Do I need both on one route?
Sometimes. A reflective sleeve shields a run across a gap while a coated sleeve protects the section that gets handled or rubs against structure.