Historical
ISO 8137:1986
"Hydraulic fluid power -- Single rod cylinders, 250 bar (25 MPa) series -- Port dimensions"
Lays down the port dimensions for cylinders as required for interchangeability of commonly used hydraulic cylinders. The table contains the bore sizes as follows: 50, 63, 80, 100, 125, 160, 200, 250, 320, 400, 500 mm; and for square and rectangular flanges the nominal flange sizes (DN): 13, 19, 25, 32, 38 mm.
International Organization for Standardization [iso]