When sourcing bottom loading valves, you must prioritize API RP 1004 compliance, which ensures the coupler interface is standardized for international petroleum transport. Key technical factors include the nominal diameter (typically 4 inches), the maximum working pressure (usually 75-100 PSI), and the flow rate capacity (up to 2,500 L/min). Additionally, verify the seal material; Viton (FKM) is preferred for its superior resistance to high-octane fuels and chemicals compared to standard Buna-N seals.