Storage Tank Emissions Calculation Tool

The purpose of this tool is to calculate working and standing losses from hydrocarbon storage tanks. Calculations are based on AP-42 (06/2020), Section 7.1.

Directions

Enter information into each of the input boxes below.  All inputs are required unless marked "Optional".  Additional boxes may appear as information is entered.  Click on the "Next-->" button to proceed once all the information is entered for each section.

For additional information regarding a specific input box, please refer to the associated tooltip (question mark symbol) to the right of the box.  Note: not all input boxes have an associated tooltip.

Note: This tool only calculates the emissions if using...

● The following tank types:
    ○ Vertical Fixed Roof
    ○ Horizontal

● The following compatible internet browsers:
    ○ Google Chrome
    ○ Microsoft Edge
    ○ Mozilla Firefox (some formatting issues may occur)
    ○ Most mobile devices
    ○ (Not compatible with Internet Explorer)

Identification





Site Selection



Tank Contents

? Select 'Calculator Database' to select a liquid from the AP-42 liquid database.

Select 'Manual Entry' to manually enter values for the liquid properties.

Tank Dimensions




? If unknown:
  ○ For vertical tanks, enter '1'.
  ○ For horizontal tanks, enter '0'.

Value must be less than the average liquid height and maximum liquid height.

? Typically assumed to be at the half-full level.

Value must be greater than the minimum liquid height, but less than the maximum liquid height.

? For vertical tanks:
  ○ Must be less than shell height.
  ○ If unknown, use 1 ft less than the shell height.

For horizontal tanks:
  ○ Must be less than tank diameter.
  ○ If unknown, use (π/4)*D.

Value must be greater than the minimum and average liquid height, but less than the shell height.

? Select 'Yes' if vapors from tank truck loading operations are routed back to the storage tank.


Shell Characteristics




Roof Characteristics




? If unknown, enter '0' to let the tool calculate based on the entered data below.

? If unknown, use '0.0625' (default).

? If unknown, use shell diameter (default).

Breather Vent Settings

? If unknown, use '-0.03' (default).

Value must be less than the breather vent pressure setting.

? If unknown, use '0.03' (default).

Value must be greater than the breather vent vacuum setting.

? Required only if the breather vent pressure setting range is greater than ± 0.3 psig.
  ○ Enter '0' if the tank is held at atmospheric pressure.
  ○ Otherwise, enter the actual gauge pressure setting of the tank.


Heating/Insulation Options

? Note: standing losses from under groun storage tanks, which can experience relatively fast vapor growth after the ingestion of air and dilution of headspace, are addressed in Section 5.2 of AP-42.

? Select 'Yes' if any of the following apply:
  ○ The tank is maintained at a constant temperature.
  ○ The tank is maintained at a set temperature range.
  ○ The tank receives hot stocks.

Heating Characteristics

Note: Site-specific measurements are required.

? Use '365' if no heating cycles.

Value must be greater than or equal to 365.

? Should be based on measured data.

Value must be less than or equal to the maximum liquid temperature.

Value must be greater than or equal to 460°R.

? Should be based on measured data.

Value must be greater than or equal to the minimum liquid temperature.

Value must be greater than or equal to 460°R.



Notice: This tool does not yet work for floating roof tanks.

Calculations

a. Select the calculation and output options below:

? Annual: a single run based on the annual throughput.

Monthly: not yet functional.

? 'Detailed' will display the following:
  ○ Input Summary
  ○ Meteorological Data
  ○ Liquid Data
  ○ Calculation Details
  ○ Emissions Summary

'Summary' will only display the following:
  ○ Input Summary
  ○ Emissions Summary


b. Click the "Run Calculation" button to see output.





Throughputs