Calcium silicate vs Expanded perlite

Near-twins (rigid, 650 °C, similar λ). Perlite's card: low chlorides for austenitic stainless (SCC fear); CalSil's: availability and walkability track record.

Specification

Side by side

	Calcium silicate	Expanded perlite
Max service	650 °C	650 °C
Density	220–260	180–220
Standards	ASTM C533 Type I	ASTM C610
Forms	rigid pre-formed sections and blocks	rigid sections and blocks (often silicate-bonded)

Computed equivalence · DN100

Thickness for the SAME heat loss

Duty	λ Calcium silicate	λ Expanded perlite	Calcium silicate thickness for EQUAL loss to 50 mm of Expanded perlite
100 °C	0.056	0.061	45 mm vs 50 mm
250 °C	0.067	0.070	47 mm vs 50 mm
400 °C	0.076	0.079	47 mm vs 50 mm

Bisection on the cylindrical conduction equation; λ at mean temperature per each material's published curve. Full per-material tables: Calcium silicate · Expanded perlite.

The whole field at this duty

All materials, DN100 at 100 °C

Material	λ W/m·K	Loss W/m	Surface	Saving €/m·yr	t CO2/m·yr
Stone wool (mineral wool)	0.041	31	25 °C	€125	0.5
Glass wool	0.038	29	24 °C	€126	0.5
Ceramic fibre (RCF / AES blanket)	0.060	44	27 °C	€119	0.4
Aerogel blanket	0.023	18	23 °C	€131	0.5
Calcium silicate	0.056	42	26 °C	€120	0.4
Expanded perlite	0.061	45	27 °C	€118	0.4
Cellular glass	0.047	35	25 °C	€123	0.4
Microporous (fumed-silica) panels	0.022	17	23 °C	€132	0.5
Elastomeric foam (FEF)	0.040	30	24 °C	€125	0.5
PIR / PUR rigid foam	0.028	21	23 °C	€130	0.5
E-glass needle mat	0.045	34	25 °C	€124	0.5
Silica needle mat / fabric	0.055	41	26 °C	€120	0.4

DN100 pipe at 100 °C, 50 mm insulation, per metre of pipe; bare loss 287 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).

FAQ

Questions on this topic

Is calcium silicate better than expanded perlite?

Near-twins (rigid, 650 °C, similar λ). Perlite's card: low chlorides for austenitic stainless (SCC fear); CalSil's: availability and walkability track record.

How much thinner can calcium silicate be than expanded perlite?

At 100 °C duty, 45 mm of calcium silicate matches 50 mm of expanded perlite (computed for a DN100 pipe, ASTM C680 simplified). The ratio shifts with temperature because both λ curves rise at different rates.