Flow and Consumption

The most basic metrology, no matter what you are actually measuring, comes down to two basic things FLOW and CONSUMPTION. Beyond that there can be issues of qualities of what flows or is consumed. And there can be issues of the toppolgical/spatial distribution of flow/consumption. For the sharp, FLOW is just the time rate of change of CONSUMPTION (dCONSUMPTION/dt), but it is sometimes thought of inversely as CONSUMPTION being the accumulation of FLOW over time (the time integral of FLOW).

Enough generalities. Water is a good concrete thing to think about. We can measure its flow, or we can measure totals of water consumed. One can look at qualities of water too like temperature or purity/salinity.

Electricity is the omniprsent modern meterable. And it is the most often confused. One loses sight of Energy=CONSUMPTION and Power=FLOW at one's peril. Too many people lightly ask "How much Power am I using?" when they really mean Energy. Most people understand interest versus principle/capital better (which is also arcane at best), and that is part of why we have such problems getting the rational economics of energy policy right.

Natural Gas and Steam are much like water, though pressure and changes of "quality" due to the nature of the plumbing/transport system are key for gases.

Oil flow tends to be exactly analagous to water.

Then one can go to more exotic materials like printing ink in a printing plant, or grain in a feedmill, or spirits in a distillery, soda cans in a vending system, bits in a router, or even coins/bills in a cash control system.

And one can go to smaller or larger scale. It is one thing to talk about flow past a given point through a given conduit. A network of meters demands a topological analysis, and there are economies to be had through understanding detailed distribution.

Think about why people use just in time manufacturing and ask how they could do such without monitoring flow in the supply network.