Index: Foreword page 3 The Settings page Precision settings page 4 Imperial System page 5 Metric System page 5 Use Table 56 page 6 Use dens 11 page 6 ASTM 1980 page 6 ASTM 2007 page 6 The main calculator screen Selecting density format page 7 Selecting volume format page 8 Selecting temperature format page 9 Selecting pressure format page 9 Selecting Alpha format page 9 Selecting cargo type page 10 Export data page 11 Worked examples page 11 Quantity records: Exporting to database tool Selecting cargo type page 13 Selecting density format page 14 Selecting temperature format page 14 Selecting pressure format page 14 Selecting volume format page 14 Selecting alpha format page 14 Using the soft menu: Show list of entries page 15 Using the soft menu: Save entry page 16 Using the soft menu: Delete entry page 16 Using the soft menu: Recalculate page 16 Copyright @ MooringMarineConsultancy 2014 Page 1
Oil conversion tool Density and temperature conversions page 17 ASTM tables version 2004 / 2007 look up tool page 17 Fuel blending: blending two components Concept page 18 The various entries page 19 Fuel blending: Density after blend Concept page 19 The various entries page 20 LPG / NGL conversion tool Table 23E: observed density to relative density @ 60 page 21 Table 53E: observed density to density @ 15 page 21 Table 59E: observed density to density @ 20 page 21 LPG density calculator tool Temperature range page 22 Choosing a constituent page 22 Mole fractions page 22 Vapor pressure page 22 Error messages page 22 LPG / NGL liquid calculation tool Required entries page 23 LPG / NGL vapor calculation tool Required entries page 23 Copyright @ MooringMarineConsultancy 2014 Page 2
Foreword Oil Calculator Pro User Manual 2014 This user manual attempts to explain all utilities and functions of Oil Calculator Pro in detail, and provides the user with enough background information to enable efficient and comfortable use of the app. Although most of the functionality is intuitive enough and designed with an aim towards intuitivity, the underlying algorithms and the way the settings work and affect the outcome of calculations are considered to be sufficiently complex that they justify more detailed explanation. This is the first version of the user manual, and it is the intention of the author to publish future updates as necessary, based on feedback received from customers and readers. To this end, you are invited to submit any queries, comments and / or criticism either as a comment on our website (hhtp://mooringmarineconsultancy.wordpress.com), or through a review in Google Play. Copyright @ MooringMarineConsultancy 2014 Page 3
The Settings page The settings page provides user settings that are applicable throughout the app. They are saved within the app whenever the user makes a change to them, and changes take effect immediately. Precision settings: For various calculated values, the user can choose the number of decimals to be displayed. By default the precision settings are as follows: - For Volume Correction Factor: o 5 decimals (when using 2004/2007 tables) o 4 decimals (when using 1980 tables) o Can be manually overridden, minimum 3, maximum 6 decimals - For Gross Standard Volume (if in M³): o 3 decimals. The same applies for Gross Observed Volume o Minimum 3, maximum 6 decimals - For Long Tons: o 2 decimals. o Minimum 1, maximum 3 decimals - For Metric Tons (Both in vacuo and in air): o 3 decimals. o Minimum 2, maximum 4 decimals - For Barrels: o 0 decimals. o Minimum 0, maximum 2 decimals There are two buttons, one for saving settings and one for selecting the defaults. It is not really necessary to use the save button, settings are saved automatically. When the user presses the default values button, only the precision settings revert to the defaults. Copyright @ MooringMarineConsultancy 2014 Page 4
Imperial System: When selected, all volume correction calculations for oil (i.e for non LPG/NGL) are carried out using US Imperial standards, meaning that for calculating the VCF for crude oil, table 6A is used, for products table 6B is used etc. Also the temperature, density and volume units are set accordingly; volume units will be set to Barrels, temperature will be set to Fahrenheit and density unit will be set to API as long as we are dealing with crude, products and lubricating oils. Please note that any such default settings can at any time be overridden, however the calculations are performed using the appropriate set of tables based on this setting. Also, the volume setting for the main calculator is by default M³ because the user has a whole range of different units to choose from there. Once the user sets a different unit here, this remains the default even when the user quits the app, until it is changed the next time to something different. Metric System: When selected, all volume correction calculations for oil (i.e for non LPG/NGL) are carried out using SI Metric standards, meaning that for calculating the VCF for crude oil, table 54A is used, for products table 54B is used etc. Also the temperature, density and volume units are set accordingly; volume units will be set to M³, temperature will be set to Celsius and density unit will be set to density 15 as long as we are dealing with crude, products and lubricating oils. This settings has no effect on NGL / LPG calculations. Copyright @ MooringMarineConsultancy 2014 Page 5
Use Table 56: This setting is only applicable when using SI Metric system; it gives the user the choice to calculate Metric Tons in air using Table 56, or simply using density @ 15 minus 11 points. The reason for this option is that there are numerous locations in the world where surveyors actually use density @ 15 minus 11 points instead of Table 56. The preferred option is obviously to use table 56. Use dens 11: See use table 56: using this setting, density in air is calculated as (dens in vacuo 11 points). Example: d15(vac) = 986.5 => d15(air) = 985.4. ASTM 1980: When this setting is selected, all VCF calculations, API / density conversions and density / API reductions to 60F/15C are carried out using 1980 version tables. This setting does however not have any effect on LPG / NGL calculations since those are all done using API MPMS 11.2.4, edition 2007. Also when ASTM 1980 is selected, calculation of CTPL (correction for temperature and pressure of a liquid) and in the main calculator screen calculation of table C (Special Applications) is not possible. Instead, only the 1980 version volume correction factor is calculated, and any API / density conversions and API / density reductions are carried out using 1980 tables. Precision setting for the VCF calculation is automatically set to 4 decimals, although this can be overridden by the user to any other value, in the settings page. In the main calculator screen, entries for pressure and alpha (thermal expansion coefficient) as well as the unit selectors for pressure and alpha are consequently disabled in this case. Please note also that this setting does NOT have any effect on the outcome of ASTM table look ups in the Oil Conversion tool, because those look ups are solely based on 2004/2007 tables. ASTM 2007: This is the opposite of the 1980 settings. All calculations are carried out using 2004/2007 table versions; in the main calculator screen (and the quantity records editor as well) calculation of Special Applications is now enabled, as well as the correction for both pressure and temperature. Unit selection for alpha and pressure units is also enabled now. Precision for the VCF calculations is automatically set to 5 decimals, but can be overridden manually. Copyright @ MooringMarineConsultancy 2014 Page 6
The main calculator screen Selecting density format: By default the density format is set to either API @ 60 or density @ 15, depending on whether the user has selected Imperial system or Metric system in the settings page. If the user wants to change the density format, simply press the density field on the right side, and choose the desired format. You can choose between density 15, API 60, relative density (60), density 20, or observed density. If the density field contains any value prior to selecting a new density format, the value will be converted to the newly selected density format automatically, based on the table version setting in the settings page. For example: Table version used is 2007, Imperial system is selected, API value is 12.4 After selecting dens 15, the converted value of 982.7 is showing in the density field. Please note that except for dens20, other density units get converted to dens15 automatically during calculation and GSV is at 15 deg C. When using dens20, GSV at 20 deg C is calculated. Copyright @ MooringMarineConsultancy 2014 Page 7
Selecting volume format: Selecting volume format does not only serve to specify a volume in either M³ or Barrels, it also serves to indicate what to calculate based on which input parameters. Not only is it possible to calculate results based on Barrels or M³ observed, if the user selects for example MT air, then gross observed and gross standard volume, as well as Barrels, MTons vac, Gallons and Long Tons will be calculated based on the input density / API, temperature and MTons air. In other words, reverse calculation. To show this function in an example, considering the following set of parameters: Metric settings used. Using tables 2004/2007. Using Table 56. Density = 965.2, Heavy Fuel Oil (i.e Product ). Observed temperature = 36.7 deg C Metric Tons in air = 5,000 This gives the results shown below: Entering instead a GOV of 5267.086 M³ gives: Copyright @ MooringMarineConsultancy 2014 Page 8
Selecting temperature format: Selecting temperature format both changes the used temperature format and converts any existing temperature value to the newly selected unit. In other words, if the user has entered a temperature of 36.7 deg C, and then selects deg F, the new temperature will automatically read as 98.06 deg F. Selecting pressure format: Selecting pressure format both changes the used pressure format and converts any existing pressure value to the newly selected unit. In other words, if the user has entered a pressure of 240 psi, and then selects Bar, the new pressure will automatically read as 16.55 Bar. Selecting alpha format: Selecting alpha format both changes the used alpha format and converts any existing alpha value to the newly selected unit. In other words, if the user has entered an alpha of 0.0009004 /deg C, and then selects /deg F, the new alpha will automatically read as 0.000500222 /deg F. Copyright @ MooringMarineConsultancy 2014 Page 9
Selecting cargo type: The available cargo types are: - Product - Crude - LubOil - Special Application - LPG / NGL Depending on the type of cargo selected and the table version selected in the settings screen, the appropriate ASTM tables are used to calculate the Volume Correction Factor. Product, Crude and LubOil speak for themselves, they refer to tables B, A and D respectively, be it either 6B, 6A, 6D or 54B, 54A or 54D. Special Application can only be selected if in settings the 2004/2007 tables setting has been chosen. Special Application refers to the C version of each table, such as 6C, 54C etc. These tables are used when calculating the volume correction factor for products to which the established formula for calculating the thermal expansion coefficient cannot be applied, such as for example denatured Fuel Ethanol and Gasoline. More detailed information can be found in our website (http://mooringmarineconsultancy.wordpress.com). When calculating the volume correction factor for special applications, only the observed temperature and the thermal expansion coefficient alpha as declared by the suppliers of the cargo are required to find the corresponding VCF (or CTL as it is called nowadays). The density is then used to calculate volumes and weights. Please note that the volume correction factor in this case is a CTPL, a combination of both pressure and temperature corrections. If pressure is unknown, the entry can be left blank and the standard pressure will be assumed. For several products such as 99% denatured Fuel Ethanol the thermal expansion coefficient is well known, and stated to be: 99% denatured Fuel Ethanol: 0.000599 /deg F, or 0.001078 /deg C 95-99% denatured Fuel Ethanol: 0.000603 /deg F, or 0.001085 /deg C Copyright @ MooringMarineConsultancy 2014 Page 10
LPG / NGL: these are calculated using tables 23E, 24E, 53E, 54E, 59E and 60E as per API MPMS Chapter 11.2.4 version 2007. Neither US Imperial nor SI Metric system settings have any effect on the outcome of calculations for LPG /NGL. Also when calculating for LPG / NGL, no inputs are accepted for pressure and alpha. Export data: When the user presses Export data all data fields are exported into a database. The app will ask the user for an entry title, and all data in the calculator screen will then be copied into the created database entry. For more info see page 13, Quantity records. Worked examples: The following examples have been provided to give the user an idea of what can be accomplished in the main calculator screen, and how to obtain the results under specific circumstances: 1. A tank containing crude oil with a density in vacuum of 867.3 and observed temperature of 38.5 deg C has been measured and is found to contain a total volume of 25,500 Bbls. Calculate the quantity in Bbls at 60 F and long tons using Imperial standards as per 1980 tables. Solution: Select Imperial System and ASTM 1980 in settings, select dens15, GOV BBLS, Crude and deg C in the main calculator screen. Enter 867.3 in the density field, 38.5 in the temperature field and 25,500 in the volume field The results will show: VCF = 0.9811 GSV(M³) = 3,977.553 LTons = 3,388.68 Bbls(60F) = 25,018 2. A ship s tank has been measured and contains 12,521.364 M³ of Gasoil, with an observed temperature of 33.3 deg C and a density in vacuum of 834.7. Calculate the quantity in Metric Tons in air using Metric standards as per 2004/2007 tables. Solution: Select Metric System, Table 56 and ASTM 2007 in settings. Select dens15, GOV M³, Product and deg C in the main calculator screen. Enter 834.7 in the density field, 33.3 in the temperature field and 12,521.364 in the volume field. The result will show: VCF = 0.98431 GSV(M³) = 12,324.904 MT(Air) = 10,274.410 Copyright @ MooringMarineConsultancy 2014 Page 11
Worked examples(continued): 3. A shore tank containing 99% + denatured Fuel Ethanol contains 5,225 liters at 20 C. The alpha coefficient is 0.000599 / F or 0.001078 / C. What is the quantity in liters at 15 C using SI Metric standards and ASTM tables version 2007? Density at 15 C in vacuum is 762.5. Solution: Select Metric System, ASTM 2007 in settings. Select dens15, GOV M³, Special applic, /deg C for alpha and deg C for temperature in the main calculator screen. Enter 5.225 in the volume field, 20 in the temperature field, 762.5 for density and 0.001078 in the alpha field. The result will show: VCF = 0.99461. M³ 15 C = 5,197 4. The density at 15 C of a 99% + denatured Fuel Ethanol is given as 790.45. What is the density at 20 C? Solution: Select Metric System, ASTM 2007 in settings. Select dens15, GOV M³, Special applic, /deg C for alpha and deg C for temperature in the main calculator screen. Enter 790.45 in the density field, 20 in the temperature field and 0.001078 in the alpha field. Now select dens20 using the density format button. The density is automatically converted and will now show as 786.2 (rounded off to 1 decimal from 786.19). 5. The density of a tank of Naphtha is given as 765.3 at 20 C. The observed volume in the tank is 23,456 M³ while the observed temperature is 24.6 C. What are the weights and volumes according to ASTM 2007 using SI Metric standards? Solution: Select Metric System, ASTM 2007 and Use Table 56 in settings. Select dens20, GOV M³, Crude, and deg C for temperature in the main calculator screen. Enter 765.3 in the density field, 24.6 in the temperature field and 23456 in the volume field. The results show: VCF = 0.99518 GSV = 23,342.942 M³ at 20 C MT(Vac) = 17,864.354 MT(Air) = 17,839.143 LTons = 17,557.40 Bbls = 146,908 Gallons = 6,170,149 If we convert the dens20 to dens15, you will see that VCF, GSV, Gallons and Bbls change significantly but the tonnes hardly change. (The weights should not change at all, but their change is due to rounding differences): VCF = 0.99001 GSV = 23,221.675 M³ at 15 C Bbls = 146,144 / Gallons = 6,138,057 Copyright @ MooringMarineConsultancy 2014 Page 12
Quantity records: Exporting to database tool When first opened, if no entries exist the user will be asked to enter a new entry title. This title can at any time be changed by the user. Created records can be copied, edited and deleted. Any changes made to an entry will automatically be updated in the database. The user has the option to change cargo type, temperature format, density format, volume format and pressure format, just like in the main calculator screen. When data is exported from the main calculator screen into the quantity records editor, all settings and values are copied into the created entry, and all buttons and text fields reflect the settings as copied. By changing the cargo type, density format, temperature, pressure or volume format, recalculation is automatically invoked and the updated values will reflect the changes as made by the user. Recalculation can also be invoked manually using the soft menu. Just like in the main calculator screen, any density unit except dens20 is automatically converted internally to dens15 during calculation and GSV is calculated at 15 C (if SI Metric System is selected), whereas if dens20 is used as density unit, GSV is calculated at 20 C. When Imperial System is selected, GSV is calculated at 60 F regardless, and all density units are internally converted to API at 60 F. Selecting cargo type: As in the main calculator screen, the available cargo types are: - Product - Crude - LubOil - Special Application (only when ASTM 2007 is selected in settings) - LPG / NGL Upon selecting a different cargo type, all values are automatically recalculated. Copyright @ MooringMarineConsultancy 2014 Page 13
Selecting density format: As in the main calculator screen, the available density formats are: - Density 15 - API 60 - Relative Density - Density 20 - Observed Density Depending on whether SI Metric system or Imperial system has been selected, gross standard volume is calculated at either 60 F or 15 C with the exception of density 20 when using SI Metric system; in this case standard volume is calculated at 20 C. Internally all density formats are automatically converted to density 15 when using SI Metric system (except dens 20) or API 60 (when using Imperial system). As seen from worked example (5) on page 11, the calculated weight is almost the same whether using dens20 or the converted dens15. In theory the outcome should be exactly the same, but minor differences occur due to rounding off errors. Selecting temperature format: When selecting a different temperature format, the existing value is automatically converted and all values are recalculated although no difference in outcome will be experienced of course. Selecting pressure format: When selecting a different pressure format, the existing value is automatically converted and all values are recalculated although no difference in outcome will be experienced. Selecting volume format: When selecting a different volume format, the existing value is automatically converted and all values are recalculated with the results showing in M³, Liters, Bbls or Gallons as appropriate. Unlike in the main calculator screen, it is not possible here to reverse calculate Metric Tons etc. Selecting alpha format: Like in the main calculator screen, choosing alpha format is done by pressing the button Alpha. If the alpha field contains a value it is automatically converted. Internally the alpha value is always converted to /deg F. Copyright @ MooringMarineConsultancy 2014 Page 14
Using the soft menu. Show list of entries: The soft menu is accessible either using the menu button (normally the left hand button on the phone) or pressing the soft menu button on the screen, as seen on tablets for example: Soft menu button on tablets Actual soft menu in action After activating the soft menu, once you select show list of entries, the list of available entries is shown. If no entries are available the list shows one entry called Create new entry which when selected, will ask the user to enter a title for an entry. If entries are available then the one selected will be loaded and data will be displayed accordingly. Copyright @ MooringMarineConsultancy 2014 Page 15
Save entry: When selecting Save entry, if no title has been entered in the title field, the app will automatically generate a title consisting of date and time, otherwise the entry data will be saved as the title entered by the user. If the user leaves the quantity record editor page without saving and the entry contains unsaved data, the app will automatically save any changes. Delete entry: When selecting Delete entry, the current entry (if any) will be deleted from the database, after the user confirms deletion. If the user wants to delete several entries from the database then the way to do so is to select each entry using the Show list of entries, and upon loading of each entry use the menu again to select Delete entry. Recalculate: Although calculations are done automatically in most cases there may occasionally be a situation in which values are not recalculated automatically. If the user is unsure whether values have been recalculated after entering new data, selecting Recalculate will force recalculation of all current data. Copyright @ MooringMarineConsultancy 2014 Page 16
Oil Conversion Tool The oil conversion tool consists of two sections: Density and temperature conversions: The upper section holds the necessary fields for converting both deg C and deg F, as well as the fields for entry of observed density, density 15, density 20, Relative density and API 60. All fields are updated automatically as data is entered. The conversions are only carried out using ASTM 2007, regardless of the settings in the settings screen. ASTM tables 2004/2007 look up tool: The lower section holds the ASTM 2007 petroleum tables. The desired table is selected using the green button with default title Table 5. When pressed, the button activates the list of available tables and the user can then select the required table. The values from the ASTM tables are only calculated using ASTM 2007, regardless of the settings in the settings screen. If the user specifically wants to use ASTM 1980 data, then he can get data for table 54 and table 6 from the main calculator screen. For table A, B and D density / API as well as a temperature must be entered to obtain the results. For table C (the special applications tables), the thermal expansion coefficient and a temperature must be entered. The thermal expansion coefficient is entered either in /deg C or /deg F depending on the table. For instance, when using table 6, alpha is entered in /deg F, whereas when using table 54 alpha is entered in /deg C. This is slightly different from the main calculator screen, where the user can choose either /deg C or /deg F as input format. Copyright @ MooringMarineConsultancy 2014 Page 17
Fuel blending Tools The fuel blending tool consists of two sections: Blending two components: Concept: When blending two components in a ship s cargo tank, normally the term load on top is used to indicate that the two components are loaded together into one space. The term load on top is however inaccurate in this day and age since in actual fact both components are normally loaded into the tanks using the ship s bottom lines, and the second component consequently is loaded below the first component, and not on top of it. When loading two components with the objective of blending them, the blending process relies on the difference in density of the components to ensure that both components eventually become homogeneously mixed. The only way to ensure that mixing actually takes place is to load the heaviest component first, and the lighter component afterwards, thereby forcing the lighter component to be pushed up through the heavier component. Heavier and lighter in this context refers to the actual density (i.e. at observed temperature) rather than to the density at 15 C or 60 F. In other words we need to compare the weight correction factor for the two components to find out which is the heavier one and which is the lighter one. The Blending two components tool helps with this; upon entering the required data, it will indicate which component to load first. It will also calculate the average density and the total volume and weights after blending. The average density and total volume is calculated taking shrinkage into consideration. It is a well known fact that when mixing two hydro carbons with different density, the total volume after mixing is not equal to the sum of the two volumes. Instead in most cases the final volume is slightly reduced due to the shrinkage that occurs (although there are certain cases where the shrinkage can be negative and produce a volume bigger than the sum of the two constituents). The shrinkage is calculated in accordance with API MPMS Chapter 12.3 and shown separately. Copyright @ MooringMarineConsultancy 2014 Page 18
Blending two components(continued): The various entries: Only six entries are required: observed volume, observed temperature and density 15 (or API 60, depending on whether SI Metric or Imperial system has been selected in settings). At the bottom of the page there is a button which enables the user to select either crude, product or lubrication oil as medium. If mixing crude plus product, then crude should be selected. If mixing two products, product should be selected. The shrinkage factor for crude oil and general products is fairly well known, however for lubricating oils there is no data available and consequently shrinkage is not calculated when lubricating oil is selected as cargo type. Density after blend: Concept: The Density after blend tool is a slight variation on the first blending tool. It assumes that we have a tank loaded with a certain volume of observed temperature and given density, and we are loading a second volume with known density on top. The temperature after loading the second volume is known, as well as the total volume loaded. The formula for shrinkage is used in this case to establish the theoretical loaded volume. This volume will be slightly higher than the loaded volume obtained from the difference between volume before and after (that is, for cases where heavy fuel oils or heavy fuel oil and crude of different density are mixed). You will see therefore a different final density than expected on the basis of the two entered volumes, especially when mixing components with significantly different densities. The shrinkage factor for crude oil and general products is fairly well known, however for lubricating oils there is no data available and consequently shrinkage is not calculated when lubricating oil is selected as cargo type. Copyright @ MooringMarineConsultancy 2014 Page 19
Density after blend(continued): The various entries: Only six entries are required: observed volume, observed temperature and density 15 (or API 60, depending on whether SI Metric or Imperial system has been selected in settings) before blending, as well as final observed volume, observed temperature, and density of the second component. At the bottom of the page there is a button which enables the user to select either crude, product or lubrication oil as medium. If mixing crude plus product, then crude should be selected. If mixing two products, product should be selected. Copyright @ MooringMarineConsultancy 2014 Page 20
LPG / NGL conversion tool The LPG / NGL conversion tool consists of three sections: Table 23E: observed density to relative density @ 60 F: Table 23E converts observed density to relative density at 60 F. Input of temperature can be in either deg C or deg F. In this section there is also an option to convert density at 15 C to relative density at 60 F. Table 53E: observed density to density @ 15 C: Table 53E converts observed density to density at 15 C. Input of temperature can be in either deg C or deg F. Table 59E: observed density to density @ 20 C: Table 59E converts observed density to density at 20 C. Input of temperature can be in either deg C or deg F. Copyright @ MooringMarineConsultancy 2014 Page 21
LPG density calculator tool The LPG density calculator uses the Frances formula to calculate the density at the observed temperature of an LPG mixture based on the amount of each of its constituents. Temperature range: The vapor and liquid temperatures are limited between -60 C and +30 C. Choosing a constituent: A maximum of 5 constituents can be entered. The following constituents are available to chose from: - Ethylene (C2H4) - Ethane (C2H6) - Propene (C3H6) - Propane (C3H8) - n-butene (n-c4h8) - n-butane (n-c4h10) - i-butane (i-c4h10) - n-pentane (n-c5h12) - i-pentane (i-c5h12) - n-hexane (n-c6h14) - n-heptane (n-c7h16) Each constituent can be entered only once. If the user attempts to use the same constituent more than once, an error message will show. Mole fractions: For each constituent entered, a fraction value between 0 and 1.0 must be entered. The sum of the fractions must be 1 or the app will show an error message. Vapor pressure: This is the absolute vapor space pressure in Bar. Error messages: The following error messages will be generated depending on wrongly entered data: - constituent entered more than once - sum of fractions not equal to one - missing fraction for constituent - vapor temperature too high or too low - liquid temperature too high or too low Copyright @ MooringMarineConsultancy 2014 Page 22
LPG / NGL liquid calculation tool The LPG/NGL liquid mass calculation tool calculates weight in air and vacuo based on the density as specified by the supplier of the LPG or NGL. Either relative density or density at 15 C can be entered, relative density is automatically converted to density at 15 C. Required entries: - Density: as above - Liquid temperature - Shrink factor: normally given in the tank calibration table. If not entered, is assumed 1. - Observed volume LPG / NGL vapor calculation tool The LPG/NGL vapor mass calculation tool calculates weight in vacuum based on vapor temperature, tank vapor pressure, atmospheric pressure and molar weight. Temperature can be entered in either deg C or deg F. The tank vapor pressure is relative, not absolute. The molar weight is normally given in the data sheet as furnished by the supplier of the cargo. - Vapor temperature - Tank vapor pressure (gauge) in kpa - Atmospheric pressure in kpa - Molar weight - Observed vapor volume - Shrink factor: normally given in the tank calibration table. If not entered, is assumed 1. Copyright @ MooringMarineConsultancy 2014 Page 23