How is tubing typically sized in hydraulic systems?

In hydraulic systems, tubing is typically sized by outside diameter because this measurement is crucial for connecting and sealing components within the system. The outside diameter is essential to ensure compatibility with fittings, hoses, and other system parts, allowing them to properly couple without leaks or pressure loss. Additionally, the outside diameter is a standardized measurement, facilitating easier procurement and replacement of tubing across different manufacturers.

The inside diameter, while important for flow calculations and to understand the volume of fluid that can be carried, is generally more relevant in the context of hose specifications. Wall thickness is a consideration for determining the strength and pressure rating of a tube but does not establish its size. Length is necessary for installation and configuration reasons, but it does not influence the sizing process of the tubing itself. Thus, using outside diameter as the sizing standard provides a balance between practical usability and adherence to design specifications in hydraulic applications.