Liquid water flows in a thin-walled circular tube at a mass flow rate of 11 g/s. The water enters the tube at 60°C, where it is heated at a rate of 3.8 kW. The tube is circular with a length of 2.8 m and an inner diameter of 25 mm. The tube surface is maintained at a constant temperature. At the tube exit, a hydrogenated nitrile rubber (HNBR) o-ring is attached to the tube’s outer surface. The maximum temperature permitted for the o-ring is 150°C. Is the HNBR o-ring suitable for this operation? The fluid properties at 100°C are cp = 4217 J/kg∙K, k = 0.679 W/m∙K, μ = 0.282 × 10−3 kg/m∙s, and Pr = 1.75. Is this a reasonable temperature at which to evaluate the fluid properties?