SimplePFD

-a simple Python module for generating process flow diagrams (PFDs).

Author: Aslak Einbu April 2020.

The module generates .xml files for editing in https://app.diagrams.net. Flow diagrams can be generated from equipment lists or by an object oriented API. Example process flow diagram:

The above flowchart is generated from the equipment file in ./examples/mel.csv. Below is an example of a generic flowchart generated from ./examples/flowchart.csv.

Repository structure

.
├── examples		# Examples
├── images		# Example images
│ 
├── simplepfd.py	# Python module
├── mel.csv		# Example Main Equipment List (MEL)
├── example.xml		# Example PFD output
│ 
├── requirements.txt
└── README.md 

The simplePFD module consists of a single file (simplepfd.py) of ~100 lines of code + documentation and comments.

Getting started

Process components

The following PFD components are currently available as part of the module:

New flowchart units can easily be implemented by adding a new line to the components dictionary.

(Sensors are work in progress (only one sensor symbol currently available).)

Python object oriented API:

Import simplePFD module:

import simplepfd as pfd

Define PFD components:

tank_1 = pfd.Unit('Tank 1','tank')
tank_2 = pfd.Unit('Tank 2','tank')
pump = pfd.Unit('P-1','pump')

Define flows(line styles can also be edited (width, arrowhead, nolabel, dashed, color):

f1 = pfd.Flow('Tank 1','P-1')
f2 = pfd.Flow('P-1', 'Tank 2')

Define sensors and connectors:

t1 = pfd.Sensor('TT-1','TT','01')
t2 = pfd.Sensor('TT-2','TT','02')
conn_1 = pfd.Connector('TT-1','P-1')

Define PFD components and write XML PFD:

object_component = [tank1, tank2, pump, f1, f2, t1, t2, conn_1]
pfd.write_pfd("example.xml", object_component)

PFD from equiment list (MEL):

Define PFD in a MEL .csv file.

CSV headers applied:

• tag - unit or flow tag name
• type - type of component (units are component dict keys)
• flows_to - tag names as sources for outgoing unit flows ('None' if no outgoing flows.)
• MEL can alos contain any other extra columns - these will not affect PFD rendering

CSV format:

• ',' as column separation
• ';' as separation of tag flows in flows_to column
• Flow styles inside '()' separated by '&'

mel.csv:

In Ascii:

tag,type,flows_to,column1,column2
Tank 1,vessel,P1,more info, more info
P1,pump,C1(color=red&nolabel=True),more info,more info
C1,packedcolumn,air(nolabel=True);Tank 1(width=4&nolabel=True),more info, more info
air,text,None,more info, more info

Define PFD components and write .xml file:

mel_components = pfd.components_from_mel("mel.csv")
pfd.write_pfd("example.xml", mel_components)

Editor

Generated .xml PFD files can be edited in https://app.diagrams.net. After the first-time generation of a diagram, the components needs manual re-arrangement. Export the edited .xml file for saving your changes. New simplepfd operations on the file updates for changes in components and flows but keeps your saved layout.

Sankey diagrams

By manipulating line width of the different flows, simple Sankey diagrams can also be produced.

Example flowchart generated from ./examples/sankey.py.

Feature requests / TODO-list

• Implementing sensors and connectors generated from MEL
• More sensor types