When selecting oblique valves, you must prioritize material integrity and pressure ratings. Ensure the body is made of corrosion-resistant materials such as LG2 gunmetal (bronze) or high-grade brass to prevent seizing over time. The valve should typically support a working pressure of 15 bar (225 psi) and a test pressure of 22.5 bar. Additionally, verify the inlet connection type (e.g., BSP/NPT threaded or flanged) and the outlet connection (e.g., British Instantaneous, Storz, or Machino) to ensure compatibility with local firefighting equipment.