Why are control valves smaller than line size?
An undersized control valve doesn’t have the capacity to pass the required flow. But, more often than not, a control valve is too large for the application. An oversized valve is very sensitive to operating conditions. Properly sized globe valves are usually one size smaller than the line.
Is head loss the same as pressure drop?
Assuming we are talking about fluids and pipes, yes it’s the same. The head loss (or the pressure loss) represents the reduction in the total head or pressure (sum of elevation head, velocity head and pressure head) of the fluid as it flows through a hydraulic system. The head loss is unavoidable in real moving fluids.
How does density affect pressure drop?
When a gas is compressed the density increases – as the pressure is released the density decreases. Gas flowing into a pipe starts at a pressure, temperature and associated density. The frictional losses along the pipe cause a pressure loss.