Tuesday, March 1, 2011
There is a new version of API 2000 for venting calculations. ITSdesign now includes this new edition for venting. There are two aspects to the new version of API 2000. The first is that to use calculations for venting that were in the previous edition, you must be using Annex A. Annex A does have restrictions that says the liquid stored must be similar to gasoline, the maximum operating temperature of the vapor space is approximately 120 degrees F (48.9 degrees C), the tank is uninsulated, and the capacity is less than 180,000 BBL (30,000 cubic meters). If it meets these criteria and you use Annex A, the results are the same as the previous standard. If, however, you use the base standard you will find that you need a lot more information about what you are storing. You need to know if the product stored is similar to Hexane, what is the Latent Heat of Vaporization of the product stored, what is the Relative Molecular Mass of the vapor, and what is the boiling point of the liquid at the relieving pressure. If you have insulation on the tank and you wish to reduce the emergency venting requirements because of the insulation, you need to know what the thermal conductivity is of the insulation. You also need to know what the approximate latitude is for the location of the tank installation. The answers to these questions could greatly affect the venting requirements especially for normal venting. It appears from some of our preliminary calculations that the normal venting per the base standard can be significantly higher than what is required by Annex A. We have just posted a new version of our ITSdesign software that includes these new calculations.