Under Pressure

I have a good understanding of the need for oil pressure in a combustion engine but, I never gave much thought to the purpose of pressure in the cooling system.  Until I started reading about it, I’ve never even paid attention to the different types of radiators, down flow and cross flow.  The down flow style pertains more to our industry, the heavy industry, as where cross flow is widely used in automotive for lower profile. Radiators are pressurized to allow the cooling system to operate at higher than atmospheric pressure. This improves cooling efficiency and prevents evaporation and surge losses. The pressure cap increases air pressure in the system by several pounds per square inch, allowing coolant to be circulated at higher temperatures without boiling. With the greater difference between the coolant and the outside air, heat passes from the coolant faster. Simple, yet genius huh. This is where the need for the expansion tank comes in to, so that the coolant has somewhere to go during the changes in temperature and pressure. I feel like Bill Nye the science guy – BILL! BILL! BILL! BILL! You know what I’m talking about.