# Calculating R-Value AEROFLEX® EPDM™ Closed-Cell Elastomeric Foam Insulation

## WHY THERMAL INSULATION?

Mechanical insulation effectively reduces heat exchange between a pipe, duct, or equipment and its environment. An insulation’s thermal efficiency is measured by thermal conductivity (K-value). The lower the K-value, the more thermally efficient insulation is. For example, a K-value of 0.245 is preferable to .280.

## WHAT IS R-VALUE?

Thermal resistance to heat flow. The higher the number, the better. For example, an R-value of 8.2 is more thermally efficient than 7.1.

## HOW TO CALCULATE R-VALUE?

#### SHEETS / ROLLS (FLAT)

R = Thickness / K-valueR = 2.0” / 0.245 #### TUBES (RADIAL) – TUBES ARE CALCULATED DIFFERENTLY THAN SHEETS / ROLLS

Tip: R-value increases as insulation thickness increases and pipe size decreases.

Example: 1-1/2” thick insulation will generate a higher R-value on a 7/8” pipe than 2-1/8” pipe.

Ru = radius of uninsulated pipeRi = radius of insulated pipeK = K-valueln = natural logarithm Note: Thermal conductivity (K-values) and R-values are listed on Aeroflex technical data sheets.