Generation I covers the commercially available mechanical systems associated with the fluid handling components. Generation I has adopted the ANSI/ISA SP76.00.2002 miniature, modular mechanical standard. This standard precisely defines inlet and outlet ports and overall dimensions which allow Lego-like interchangeability of components, between different manufacturers. The ANSI/ISA standard is referenced by the International Electrotechnical Commission in publication IEC 62339-1:2006.
Currently three manufacturers produce the mechanical mounting system (known as a substrate) which serves as the platform for attaching various components. Since the components are bolted to the surface of the substrate, sealed by O-rings, they are sometimes referred to as surface mount devices. (The semiconductor industry has a related system; however, the sealing is done by metallic seals rather than elastomeric O-rings.) There are currently over 60 different types of surface mount components available from various suppliers who provide valves, filters and regulators as well as pressure and flow sensing devices. Although the platform for mounting various components is common among the manufacturers, the interconnections below the surface are proprietary. The following figure shows three of the common designs. (From left to right) A Swagelok system which uses various lengths of tube connectors set in rigid channels; a CIRCORTech design which uses a single block with assorted flow-tubes; and a Parker Hannifin design which uses various blocks ported together with small connectors which also serve as flow paths.