CHAPTER 4: ISO Symbols | Hydraulics & Pneumatics Either symbol set (ANSI or ISO) may be -- and is -- used in the United States. However, many companies today use the ISO symbols as their standard for work with foreign suppliers and customers. The following pages go through all standard ISO symbol information as it Author: Bud Trinkel Pneumatic Symbols - SMC Pneumatic Symbols Only when the design fails does it draw attention to itself; when it succeeds, it’s invisible. John D. Berry All the symbols you need to design your pneumatic circuit in format. Scan through and easily download the one you need.