STEAM FLOW DETECTION
As the previous equations demonstrate, temperature and pressure values can be used to
electronically compensate flow for changes in density. A simple mass flow detection system is
illustrated by Figure 9 where measurements of temperature and pressure are made with
commonly used instruments.
Figure 9 Simple Mass Flow Detection System
For the precise measurement of gas flow (steam) at varying pressures and temperatures, it is
necessary to determine the density, which is pressure and temperature dependent, and from this
value to calculate the actual flow. The use of a computer is essential to measure flow with
changing pressure or temperature. Figure 10 illustrates an example of a computer specifically
designed for the measurement of gas flow. The computer is designed to accept input signals
from commonly used differential pressure detectors, or from density or pressure plus temperature
sensors, and to provide an output which is proportional to the actual rate of flow. The computer
has an accuracy better than +0.1% at flow rates of 10% to 100%.