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Pfd Process Flow Diagram

Reference data and engineering information about pfd process flow diagram for fluid mechanics applications.

pfdprocessflowdiagramData Table

Overview

Engineering reference data for Pfd Process Flow Diagram in fluid mechanics.

Key Formulas

Reynolds Number

Re=ρvDμRe = \frac{\rho v D}{\mu}

Ratio of inertial to viscous forces — determines flow regime.

Bernoulli's Equation

P+12ρv2+ρgh=constP + \frac{1}{2}\rho v^2 + \rho g h = \text{const}

Conservation of energy for steady, inviscid, incompressible flow.

Continuity Equation

A1v1=A2v2A_1 v_1 = A_2 v_2

Conservation of mass for incompressible flow.

Darcy-Weisbach

ΔP=fLDρv22\Delta P = f \frac{L}{D} \frac{\rho v^2}{2}

Pressure drop due to friction in a pipe.

Variables

Symbol Description Unit
ReRe Reynolds number —
ρ\rho Fluid density kg/m³
vv Flow velocity m/s
DD Characteristic dimension m
μ\mu Dynamic viscosity Pa·s
PP Pressure Pa
ff Darcy friction factor —

PFD Inclusions and Exclusions

A correctly prepared Process Flow Diagram (PFD) focuses on major system components and their operational parameters, intentionally omitting detailed installation specifications.

What a PFD Should Include

  • Process piping and major equipment symbols
  • Major equipment names and identification numbers
  • Control valves and valves affecting system operation
  • Interconnections with other systems
  • Major bypass and recirculation lines
  • System ratings: minimum, normal, and maximum flow, temperature, and pressure
  • Fluid composition

What a PFD Should Not Include

  • Pipe classes and line numbers
  • Minor bypass lines
  • Isolation and shutoff valves
  • Maintenance vents and drains
  • Relief and safety valves
  • Code or class information

PFD vs. P&ID

While a PFD focuses on overall process flow and design values, a Piping & Instrumentation Diagram (P&ID) provides more detailed information for construction and operation.

  • PFD: Shows major components and process design values for system understanding.
  • P&ID: Shows all piping, instruments, and controls for detailed engineering, construction, and maintenance. It includes information that a PFD intentionally excludes, such as pipe line numbers, valve details, and relief device specifications.

References