Example no. 2
For heating applications, it is desired to check the insulation thickness required to ensure an
external insulation temperature of not more than 37°C. The hot water temperature was found
operating at a maximum temperature of 50°C. The pipe size is 1" and the insulation material used
is fibreglass encased in a metal cladding. The k-value of the insulation material is 0.035 W/m.K.
The air temperature around the pipes is 34°C.
By entering the data into the Excel spreadsheet programme, we can determine that the insulation
thickness required is at least 0.5 inch.
It should be noted that the closer the external surface temperature is to the ambient air
temperature, the thicker will the insulation be. It is not possible to have the external surface
temperature colder than the air ambient temperature, else convection will not occur.
Section 7 Page 104
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