Abstract: Difference in internal diameters of flanged fluid-flow components, such as pumps and valves, are accommodated by the present flow adapter with a much lessened space requirement. The adapter is preferably formed as a metal casting with parallel faces, and with its tapered bore, which extends from one face to the other, surrounded by a pattern of tapped holes, into which the flanges of the fluid-flow components are screwed. No nuts are used; there is no need for access to the space occupied by the adapter, between the flanges of the two fluid-flow components. Results include a much lessened installation length with only a modest loss of fluid-flow efficiency.