Microporous (fumed-silica) panels — properties, λ(T) and computed performance

Service limit ≈1000 °C · density 220–320 kg/m³ · ASTM C1676. Supplied as: rigid panels, flexible quilted forms (Promalight/WDS-type).

Honest assessment

Strengths, limits, verdict

Strengths: lambda BELOW still air even at 600–800 °C (beats everything at high temp); extreme space saving.

Limits: highest price per m2 in the industry; fragile, moisture-sensitive unless encapsulated; specialist fabrication.

Verdict: The space-critical high-temperature card: turbine casings, exhaust ducts inside enclosures, aerospace-grade jobs.

Thermal conductivity (typical published values)

Mean temperature	λ W/m·K
100 °C	0.022
200 °C	0.024
400 °C	0.028
600 °C	0.034
800 °C	0.040

λ at mean temperature — rises with T because pore radiation grows with T³.

Computed performance · ASTM C680 simplified

Microporous (fumed-silica) panels on real pipe sizes

At 100 °C (λ=0.022 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	152	15	24 °C	€67	0.24
DN50	50 mm	152	11	22 °C	€69	0.25
DN50	100 mm	152	7	21 °C	€70	0.26
DN100	30 mm	287	25	25 °C	€128	0.47
DN100	50 mm	287	17	23 °C	€132	0.48
DN100	100 mm	287	11	21 °C	€135	0.49
DN200	30 mm	551	43	25 °C	€248	0.91
DN200	50 mm	551	28	23 °C	€255	0.93
DN200	100 mm	551	17	21 °C	€260	0.95

At 250 °C (λ=0.023 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	436	45	32 °C	€191	0.70
DN50	50 mm	436	33	26 °C	€197	0.72
DN50	100 mm	436	22	23 °C	€202	0.74
DN100	30 mm	826	73	33 °C	€367	1.34
DN100	50 mm	826	50	27 °C	€378	1.38
DN100	100 mm	826	32	23 °C	€387	1.42
DN200	30 mm	1,583	127	34 °C	€710	2.60
DN200	50 mm	1,583	84	28 °C	€731	2.68
DN200	100 mm	1,583	50	24 °C	€748	2.74

At 400 °C (λ=0.024 at mean)

Pipe	Thickness	Bare W/m	Insulated W/m	Surface	Saving €/m·yr	t CO2/m·yr
DN50	30 mm	720	79	41 °C	€313	1.14
DN50	50 mm	720	57	31 °C	€323	1.18
DN50	100 mm	720	39	25 °C	€332	1.22
DN100	30 mm	1,365	128	43 °C	€603	2.21
DN100	50 mm	1,365	89	33 °C	€622	2.28
DN100	100 mm	1,365	56	26 °C	€638	2.34
DN200	30 mm	2,616	223	45 °C	€1,167	4.27
DN200	50 mm	2,616	148	35 °C	€1,204	4.41
DN200	100 mm	2,616	88	27 °C	€1,233	4.51

Assumptions: 20 °C ambient, still air (h=10 W/m²·K), €0.05/kWh fuel, 8000 h/yr, 82% boiler efficiency, 0.183 kg CO2e/kWh. Your numbers: free calculator.

Against the field

Same duty, all materials — DN100 at 250 °C

Material	λ W/m·K	Loss W/m	Surface	Saving €/m·yr	t CO2/m·yr
Stone wool (mineral wool)	0.052	112	37 °C	€348	1.3
Glass wool	0.050	106	36 °C	€351	1.3
Ceramic fibre (RCF / AES blanket)	0.060	127	39 °C	€341	1.2
Aerogel blanket	0.027	61	29 °C	€373	1.4
Calcium silicate	0.067	139	41 °C	€335	1.2
Expanded perlite	0.070	145	42 °C	€332	1.2
Cellular glass	0.058	122	38 °C	€343	1.3
Microporous (fumed-silica) panels	0.023	50	27 °C	€378	1.4
E-glass needle mat	0.050	106	36 °C	€351	1.3
Silica needle mat / fabric	0.055	117	37 °C	€346	1.3

DN100 pipe at 250 °C, 50 mm insulation, per metre of pipe; bare loss 826 W/m. λ at mean temperature; € and CO2 per metre·year at €0.05/kWh, 8000 h, 82% efficiency. Method: ASTM C680 simplified (h=10).

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FAQ

Questions on this topic

What is the thermal conductivity of microporous (fumed-silica) panels?

Typical published values: 0.022 W/m·K at 100 °C, 0.024 W/m·K at 200 °C, 0.028 W/m·K at 400 °C, 0.034 W/m·K at 600 °C, 0.040 W/m·K at 800 °C (mean temperature). λ rises with temperature — design with the mean-temperature value, not the ambient one.

What is the maximum temperature for microporous (fumed-silica) panels?

≈1000 °C continuous service for typical grades (ASTM C1676). Product-specific limits vary — check the datasheet of the exact grade.

Where is microporous (fumed-silica) panels the right choice?

The space-critical high-temperature card: turbine casings, exhaust ducts inside enclosures, aerospace-grade jobs.