Instrumentation is critical to understanding and troubleshooting all processes. Very few engineers specialize in this field,

Instrumentation is critical to understanding and troubleshooting all processes. Very few engineers specialize in this field, and many learn about instrumentation through experience, myth and rumor. A good understanding of the various types of instrumentation used on columns is a valuable tool for engineers when evaluating column performance, starting up new towers or troubleshooting any type of problem. This article gives an overview of the common types of instruments used for pressure, differential pressure, level, temperature and flow. A discussion of their accuracy, common installation problems and troubleshooting examples are also included. The purpose of this article is to provide some basic information regarding the common types of instrumentation found on distillation towers so that process engineers and designers can do their jobs more effectively. Anyone trying to complete a simple mass balance around a column understands that process data contain some error. Closing a mass balance within 10% using plant data is usually considered very good. Generally, some values must be thrown out when matching a model to plant data. Understanding which measured plant data is likely t...

‘Knitting Has Always Been Political’: Ravelry Bans Pro-Trump Content, and Reactions Flood In

But on Sunday, Ravelry, a popular website for knitters and crocheters, took a political stand when it announced that it was banning content that supports President Trump, in what it said was a resolution against white supremacy. “We cannot provide a space that is inclusive of all and also allow support for open white supremacy,” the site said in a statement explaining the decision. “Support of the Trump administration is undeniably support for white supremacy.” The policy applies to content on the site, including knitting patterns and forum posts, but not to people, according to Ravelry, which said it still welcomed Republicans and those with conservative political views. “You can still participate if you do in fact support the administration, you just can’t talk about it here,” the statement said, adding that “hate groups and intolerance are different from other types of political positions.” The announcement led to a swift and intense reaction from all corners of the knitting world, whose denizens range from twentysomethings in Brooklyn to grandmothers in the Midwest. Some people condemned the policy as liberal bias and promised to delete their accounts, while others said they...