F14 (EN 558-1 Series 14) is the standard face-to-face length for flanged ball valves and the default choice for new installations. F1 (EN 558-1 Series 1) matches the face-to-face of DIN gate valves and butterfly valves — it is used for a 1:1 replacement of an existing gate valve or butterfly valve without modifying the pipework. For installations with extremely limited space, the compact flanged ball valve KH156 offers an ultra-short alternative.