Re: Definition please
Posted by: Peter Heid (IP Logged)
Date: September 17, 2002 07:14PM
<HTML>Although all the answers cover the question, I couldn't leave this one alone. The answer has changed much over the years and a time line showing the pressure/temperature ranges used could be quite interesting. In the very early days pressure ment the steam moved into the cylinder an the vacuum of condensation did most of the work. When pressure began to be used to do work, 50 PSI might have been a tall figure. As time moved on the pressures climbed and by 1930 supercritical pressures had been acheived. the modern definition of pressures for power plants came forth at this time with low pressure up to 500 lbs, medium reached 1500, and high pressures upto 3208.2, while supercritical is any thing beyond. Most books vary but for power stations they were in this range. Of course, as it has been pointed out, the application will also help define the working ranges and a time line could made for many applications.
Peter Heid</HTML>