Expanded perlite at 250 °C — heat-loss table

λ = 0.070 W/m·K at mean temperature ((250+20)/2 = 135 °C, from the published curve). Pipe losses per metre, four thicknesses, savings vs bare.

Pipe	30 mm W/m	50 mm W/m	80 mm W/m	100 mm W/m	BARE W/m	Surface @50 mm	Saving €/m·yr @50 mm	t CO2/m·yr
DN25	85	67	55	50	241	36 °C	€85	0.31
DN50	125	94	74	66	436	39 °C	€166	0.61
DN80	165	121	93	82	642	40 °C	€254	0.93
DN100	200	145	109	95	826	42 °C	€332	1.22
DN150	275	194	141	122	1,216	43 °C	€499	1.82
DN200	344	240	172	147	1,583	44 °C	€655	2.40
DN300	487	333	234	198	2,340	45 °C	€979	3.58

Assumptions: 20 °C ambient, still air (h=10 W/m²·K combined), €0.05/kWh fuel, 8000 h/yr, 82% efficiency, 0.183 kg CO2e/kWh (DESNZ 2024). Flat surfaces at this duty: bare 2,300 W/m² → 281 W/m² at 50 mm (≈€985/m²·yr saved). Method: ASTM C680 simplified — methodology. Your exact case: free calculator.

Context

All materials 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).

Material datasheet: Expanded perlite → · temperature class: by temperature →

FAQ

Questions on this topic

How much heat does a pipe at 250 °C lose with expanded perlite?

With 50 mm at 250 °C (λ=0.070 at mean): DN50 loses 94 W/m, DN100 145 W/m, DN200 240 W/m — vs 826 W/m bare for DN100. Full table on this page.

What surface temperature does expanded perlite give at 250 °C?

≈42 °C with 50 mm on DN100 (20 °C ambient, still air). Personnel-protection targets (≤45–60 °C) may need more thickness — see the 80/100 mm columns.