Sam is part of the integrated design team that is designing a small hotel. She has been tasked with ensuring that the hot-water supply in the hotel complies with SANS 10400-XA and SANS 204. Part of this is ensuring that the hot-water service pipes are insulated according to the required minimum R-values. The pipes that Sam wants to use have a 90mm diameter. SANS 10400-XA and SANS 204 state that pipes with a diameter greater than 80mm need insulation with a minimum R-value of 1.5m²K/W.

If the insulating material (polyethylene foam) has a k-value of 0.035W/mK, how thick does it need to be to achieve the minimum R-value?

Select one:

a.

23.3mm thick

b.

52.5mm thick

c.

42.8mm thick

d.

34.5mm thick