Process Flow Diagram Symbols

"Directional control valves are one of the most fundamental parts in hydraulic machinery as well and pneumatic machinery. They allow fluid flow into different paths from one or more sources. They usually consist of a spool inside a cylinder which is mechanically or electrically controlled. The movement of the spool restricts or permits the flow, thus it controls the fluid flow. ...
While working with layouts of hydraulic machinery it is cumbersome to draw actual picture of every valve and other components.instead of pictures symbols are used for variety of components in the hydraulic system to highlight the functional aspects. symbol for directional control valve is made of number of square boxes adjacent to each other depending on the number of positions.connections to the valve are shown on these squares by capital letters.usually they are named only in their normal position and not repeated in other positions.actuation system of the valve is also designated in its symbol." [Directional control valve. Wikipedia]
The Mac template "Pneumatic 5-ported 3-position valve" for the ConceptDraw PRO diagramming and vector drawing software is included in the Mechanical Engineering solution from the Engineering area of ConceptDraw Solution Park.
www.conceptdraw.com/ solution-park/ engineering-mechanical

This PFD of jet fuel mercaptan oxidation treating was redrawn from Wikipedia file: ConvLPGMerox.png. [en.wikipedia.org/ wiki/ File:ConvKeroMerox.png]
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported icense. [creativecommons.org/ licenses/ by-sa/ 3.0/ deed.en]
"Merox is an acronym for mercaptan oxidation. It is a proprietary catalytic chemical process developed by UOP used in oil refineries and natural gas processing plants to remove mercaptans from LPG, propane, butanes, light naphthas, kerosene and jet fuel by converting them to liquid hydrocarbon disulfides.
The Merox process requires an alkaline environment which, in some of the process versions, is provided by an aqueous solution of sodium hydroxide (NaOH), a strong base, commonly referred to as caustic. In other versions of the process, the alkalinity is provided by ammonia, which is a weak base.
The catalyst in some versions of the process is a water-soluble liquid. In other versions, the catalyst is impregnated onto charcoal granules.
Processes within oil refineries or natural gas processing plants that remove mercaptans and/ or hydrogen sulfide (H2S) are commonly referred to as sweetening processes because they results in products which no longer have the sour, foul odors of mercaptans and hydrogen sulfide. The liquid hydrocarbon disulfides may remain in the sweetened products, they may be used as part of the refinery or natural gas processing plant fuel, or they may be processed further.
The Merox process is usually more economical than using a catalytic hydrodesulfurization process for much the same purpose." [en.wikipedia.org/ wiki/ Merox]
The process flow diagram (PFD) example "Jet fuel mercaptan oxidation treating" was drawn using the ConceptDraw PRO software extended with the Chemical and Process Engineering solution from the Chemical and Process Engineering area of ConceptDraw Solution Park.