“Percentages are for accountants”

Not that there’s anything wrong with that. If you’re a technical person, you have to watch out for what is hidden behind those pesky ratios. A great example in papermaking is the classic “just a couple points of sheet solids.” It’s important to remember that a couple points off the couch is very different than a couple points after the press.  The graph below illustrates what those 2 points of consistency mean at 2 different points along the machine.

So what, you say? So…

1)     A 2 point consistency drop at the couch could mean 25% more water has to be removed in the press to maintain solids out of the press.

2)     Slight variations off the couch have a significant impact on pressing efficiency.

3)     Off-couch consistency is a critical process control variable.

4)     The difference between a press operating efficiently and causing you a lot of grief is a very, very small amount of water.