Refrigeration► Book page

Hose is like flexible tubing, but it should generally be considered as PIPE.

Hose is sized by its Inside Diameter. (A notable exception to this is the case of FIRE HOSE, which is often sized by its O.D. due to its associated fitments, many of which use the O.D. as their determinant diameter.)

Hose is most typically (and traditionally) made of rubber, though modern technology has brought us myriad new materials suitable for various working fluids and physical working criteria.

Refrigeration► Specs and Standards

ISO 228-1

Pipe threads where pressure-tight joints are not made on the threads -- Part 1: Dimensions, tolerances and designation

This is the specification in force as of 2000 for BSPP threaded appliances.

souce: ISO 228-1:2000