What is the main difference between P&ID and PFD?

What is the main difference between P&ID and PFD?

#Answer :-

? Process Flow Diagram (PFD) is used for

indicating the general flow of process and equipment for helping to visualize the overall process of the in a chemical plant.

PFD will contain (main process piping, main equipment number, Equipment Name, Flow directions, Major bypass lines, Critical Control Valves that affects the process, Stream Number, Stream Designation, Process parameters like operating temperature, operating pressure, flow rate, Composition and heat duty of heat transfer equipment, Piping size and classification, Process control Instrumentation details like Transmitters, Control valves, Design Temperature and Pressure, Material of Construction of Equipment and piping, Mechanical Valves for isolation, Vents and Drains, Relief valves & Safety Valves.)

Typically, process flow diagrams of a single unit process will include the following:

·        Process piping

·        Major equipment items

·        Control valves and other major valves

·        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

·        Process control instrumentation (sensors and final elements)

·        Minor bypass lines

·        Isolation and shutoff valves

·        Maintenance vents and drains

·  Relief, Flanges and safety valves

P&ID – P&ID have general notes that will assist during Detailed Engineering, Erection and Commissioning phase, A great deal of information can be represented in a “simple” diagram. Information about the piping is represented, including pipe size, pipe material of construction, insulation, and pipe specification. Location of valves, pumps, check valves, filters, strainers, and hoses are simply displayed for an easy-to-understand and -identify arrangement.

Instrumentation details like Transmitters, Control valves with their numbers, Control input and output, Annunciation input, SIS input, solenoid valves, On-off valves, Motorized valves, Relief valves, All Mechanical valves Miscellaneous items like strainers, Vents, drains, Silencers, standpipes etc, Vendor items and interfaces, Equipment design pressure, Temperature and Material of Construction, Free draining requirements etc

Instrumentation is displayed using standardized symbols and labeling representing the process-sensing and -control elements. Instrumentation includes:

• Pressure Gages and Pressure Transmitters
• Analyzers 
• Temperature Elements 
• Flow Meters and Flow Transmitters
• Level Gages and Level Transmitters
• Weight Instruments 

Instrumentation also includes process-control devices such as actuated valves, control valves, pressure regulators, pressure-relief devices, and conservation vents.

Process control can also be represented on the P&ID to simply display how the process operates. For example, a flow meter may be used to control a valve to provide a constant flow rate to a process. Interlocks can be displayed and documented on the drawing. On a single drawing the interlocks represent what triggers an automatic response and what actions are taken.

Equipment represented on the P&ID include tanks, pumps, mixers, agitators, centrifuges, totes, drums, heat exchangers, condensers, conveyors, and filters.