Tank Protocol provides indicative, comparative estimates of routine and non-routine vapor losses from organic liquid storage tanks. It implements the emission estimation equations published in US EPA AP-42, Chapter 7 — Organic Liquid Storage Tanks (September 2025), based on correlations developed and copyrighted by the American Petroleum Institute (API MPMS Chapter 19.2).

Results are intended only to help compare relative emission magnitudes between tanks, configurations, products, and operating scenarios. They are not a substitute for the official EPA TANKS software, a certified emissions calculation, or professional engineering judgment.

You acknowledge the following limitations:

• The AP-42 equations are approximations derived from empirical data and simplifying assumptions. Emission factors are averages and may not represent any specific tank; actual emissions can differ substantially.
• Accuracy depends entirely on the quality and completeness of your inputs. Default values, estimated meteorological data, simplified geometry, and assumed liquid properties all introduce uncertainty.
• The equations do not apply to certain scenarios, including unstable or boiling stocks, deteriorated or permeated seals/fittings, heated or pressurized tanks outside the documented range, flashing service, or mixtures whose vapor pressure cannot be reliably predicted.
• Some parameters use simplified or default treatments (saturation/wind correction factors, single-component vapor pressure in place of true mixture behaviour under Raoult's Law, and screening-level non-routine assumptions). Speciated, mixture, and partial-year results may differ from a full TANKS analysis.

This tool does not constitute regulatory compliance, permitting, or reporting. Any emissions used for regulatory submissions, permit applications, fee calculations, or compliance demonstrations must be verified using the official EPA TANKS application and applicable regulatory methods, and reviewed by a qualified professional.

The developers make no warranty as to accuracy, fitness for any purpose, or regulatory acceptability, and accept no liability for decisions made on the basis of these estimates. API retains copyright to the underlying emission estimation equations.