The differential pressure flow is calculated as it is directly proportional to the square root of differential pressure, making pressure a critical component of DP Flow calculations. This calculation can be seen in more detail on the Instrumentation Tools website. The mass flow rate may vary depending on the temperature, pipe diameter, density, viscosity, and fluid/gas type. Most EMI clients use a range of measurement and control devices to ensure they have the most accurate gas, liquid and steam flow rates to ensure consistency, safety, productivity and to minimise downtime.