Ruben,
The PE rating of a line is related to its diameter not its breaking strain so as an example PE6 lines will be about .40mm in diameter but may vary quite widely in claimed breaking strain, anywhere from say 75lb to 90b. PE8 would typically be 100b to 115lb(ish). I believe the PE rating system itself came from the traditional Japanese way of categorizing silk. Over the years as lines have developed and improved the average breaking strain of any given PE rating has increased.Once upon a time a rule of thumb was the you multiplied the PE rating by 10 to determine the breaking strain of the line in pounds, as you can see, that doesn't work any more.
The American brands, like Jerry Brown, advertise the claimed breaking strain of the braid rather than the diameter of the line, as the Japanese do. What makes it even more complicated is that the actual breaking strain of the American lines is often much greater, on average, than the stated breaking strains.
Lots of pros and cons, hollow versus solid braid. If you do a search on this site you'll get a pretty comprehensive run down on those. I'm not sure why you'd want to knot hollow given that you can splice it but maybe one of our members who uses hollow can answer that.
Regards,
Trevor