text: Typically, process flow diagrams of a single unit process include the following:
  * Process piping
  * Major equipment items
  *Connections with other systems
  * Major bypass and recirculation (recycle) streams
  * Operational data (temperature, pressure, mass flow rate, density, etc.), often by stream references to a mass balance
  * Process stream names
  Process flow diagrams generally do not include:
  * Pipe classes or piping line numbers
  * Instrumentation details
  * Minor bypass lines
  * Instrumentation
  * Controllers like Level Control or Flow Control
  * Isolation and shutoff valves
  * Maintenance vents and drains
  * Relief and safety valves
  * Flanges
  Process flow diagrams of multiple process units within a large industrial plant will usually contain less detail and may be called block flow diagrams or schematic flow diagrams.