api2000API 2000. To display this page you need a browser that supports JavaScript. Cal_01, Emergency Vent Capacity Per API 2000. Cal_02, Normal Vent Capacity PerAPI 2000 – 6th Edition (Appendix A = API 5th edition) • Tank volume • Liquid flow (pump-in-out) • Pump out • Temperature change • Average storage temperature • Vapour pressure • Latitude