IPE-TM-100 General Information
Round Off Guidelines
IPE-TM-100-01
1. Purpose
This procedure puts forth guidelines for data representation (significant figures and decimal places) and rounding off numbers.
2. General
Many areas of Inflection Point Engineering do not have an official data representation and round off policies. As such, use good judgment and consider the attached guidelines which denote the highest degree of accuracy to represent on project specifications. The ABE database program contains its own set of data representation and round off rules which will automatically be used when Project Specifications are generated by ABE. See Attachment 1 for rules used by ABE to export data to Project Specifications. Tools that do not export data to ABE (PrTray, P254, etc.) have their own data representation rules. Do not spend time to make all data representation consistent to the ABE rules.
3. Round-off Guidelines
ABE uses the conventional guidelines for rounding off numbers. I.e., numbers beyond the last decimal point or significant figure from 1 to 4 will be rounded down (31.2º C becomes 31º C) and numbers between 5 through 9 will be rounded up (31.5º C becomes 32º C).
4. Guidelines for Design Pressure and Design Temperature
Use round off guidelines for design conditions in Procedure”. The resulting design conditions, when appropriate, should be entered into the ABE Calc Tool.
4.1 English Units
Enter the design conditions determined using Procedure IPE-TM-100-02. After transferring the value from the ABE calc tool to ABE, ABE will convert input to a consistent number of significant figures or decimal points.
4.2 Metric or SI Units
Determine metric or SI unit design conditions using Procedure IPE-TM-100-02. Make direct conversion from metric to English units with at least three significant digits. Enter English design conditions into ABE calc tool. Note ABE calc tools receive all input in English units and then ABE makes a final conversion to desired system of measurement units and prints output on Project Specification with significant figures/decimal points based upon rules in Attachment 1.
5. Round-off and Data Representation Guidelines for Vessels and Tray Layouts
Use guidelines in Procedure . Vessel design conditions are determined as indicated in Procedure IPE-TM-100-02.
6. Instrument Project Specification Guidelines
Instrument Project Specifications are not generated using ABE. The Instrument area has their data representation round off guidelines developed in order to meet their specific needs. The guidelines developed to generate Instrument Project Specifications will continue to be used.
7. Basic Engineering Design Questionnaire (BEDQ)
ABE imports data from the BEDQ. The BEDQ data exported from ABE will be consistent with Attachment 1. Data in the BEDQ should not have more significant figures/decimal points than indicated in Attachment 1. For example, if the temperature information provided under site conditions is given to one decimal point; i.e., low ambient temperature (used to represent MDMT) is indicated as 10.2º F, it will be rounded off to 10º F. In order to avoid confusion, change representation (with Customer agreement) for temperatures to a whole number.
8. ABE Data Representation Guidelines
ABE will only allow one data representation rule for a unit of measurement; i.e., 50.00 psig and 5635 psig each have four significant figures. This leads to some numbers that appear to be more accurate than justified (i.e., 1.000 psig); however, this is just a programming rule to which we must adjust. Do not spend time trying to modify ABE output. In most cases, user modifications to project specification output from ABE will not be possible because the cells are locked. If the ABE data representation rules do not provide the required degree of accuracy, contact the ABE Coordinator, Tool Sponsor or Procedure Sponsor and a solution will be found.
9. Heat & Weight Balance, EDI Reports, and PFD Flagging
The Excel-based reports have their own data representation rules that provide a combination of readability and the maximum number of significant figures. The data representation is fixed and not subject to user adjustment. Do not spend time trying to change data representation.
Attachment 1 – ABE Data Representation
| UNIT | FORMAT | UNIT | FORMAT | |
|---|---|---|---|---|
| % | 3 Sig Fig | kJ/(kg.degC) | 2 dec places | |
| (Btu/h)/(ft.degF) | 3 Sig Fig | kJ/(kmol.degC) | 3 Sig Fig | |
| (Btu/h)/(ft^2.degF) | 3 Sig Fig | kJ/h | 4 Sig Fig | |
| (Btu/h)/ft^2 | 3 Sig Fig | kJ/kg, kJ/kmol | 3 Sig Fig | |
| (kcal/h)/(m^2.degC) | 3 Sig Fig | kJ/m^3 | 3 Sig Fig | |
| (kcal/h)/m^2, (kg/s)/m^2 | 3 Sig Fig | Kl/day | 4 Sig Fig | |
| (kJ/h)/(m.degC), (kJ/h)/(m^2.K) | 3 Sig Fig | kmol, kmol/h | 3 Sig Fig | |
| (lb/s)/ft^2 | 3 Sig Fig | kPa | 1 dec places | |
| 10^6.Btu/h, 10^6.kcal/h | 4 Sig Fig | kPa/m | 3 Sig Fig | |
| 10^6.scf/day | 3 Sig Fig | kPa[g], kPa[a] | 4 Sig Fig | |
| A | 3 Sig Fig | kW | 1 dec places | |
| bar | 3 Sig Fig | kW/m^2 | 2 dec places | |
| bar[a], bar[g] | 4 Sig Fig | kW/(m^2.K) | 3 Sig Fig | |
| Btu/(h.degF) | 3 Sig Fig | kWh | 3 Sig Fig | |
| Btu/(lb.degF) | 2 dec places | l/h | 2 dec places | |
| Btu/(lbmol.degF), Btu/ft^3 | 3 Sig Fig | lb, lb.ft/s, lb.ft^2, lb/(ft.s^2) | 3 Sig Fig | |
| Btu/lb, Btu/lbmol | 3 Sig Fig | lb/ft, lb/ft^2 | 3 Sig Fig | |
| cm^2 | 2 dec places | lb/ft^3 | 4 Sig Fig | |
| cp | 3 dec places | lb/h | 0 dec places | |
| cSt | 3 Sig Fig | lb/lbmol | 1 dec places | |
| degC, degF | 0 dec places | lb/min | 3 Sig Fig | |
| degC.m^2/W | 5 dec places | lbf, lbf.ft | 3 Sig Fig | |
| degF.ft^2.h/Btu | 4 dec places | lbf/ft^2 | 3 Sig Fig | |
| dyn/cm, dyne | 3 Sig Fig | lbmol, lbmol/h | 3 Sig Fig | |
| fraction | 2 dec places | m | 1 dec places | |
| ft | 1 dec places | m/s, m/s^2 | 3 Sig Fig | |
| ft/s, ft/s^2 | 3 Sig Fig | m^2, m^2/h | 3 Sig Fig | |
| ft^2, ft^2/h | 3 Sig Fig | m^2.K/W | 5 dec places | |
| ft^3, ft^3/lb | 3 Sig Fig | m^3, m^3/h | 3 Sig Fig | |
| ft^3/lbmol | 3 Sig Fig | m^3/kg, m^3/kmol | 3 Sig Fig | |
| ft^3/min, ft^3/s | 3 Sig Fig | mm | 2 dec places | |
| gal[US]/h, gal[US]/min | 3 Sig Fig | Mm^2 | 3 Sig Fig | |
| Gcal/h | 3 Sig Fig | 3 Sig Fig | ||
| GJ/h | 4 Sig Fig | mN/m | 3 Sig Fig | |
| h.m^2.degC/kcal | 4 dec places | mol% | 3 Sig Fig | |
| h.m^2.degC/kJ | 5 dec places | Mpa, mPa.s | 3 dec places | |
| hp | 1 dec places | Mpa[a], MPa[g] | 3 dec places | |
| hp.h | 3 Sig Fig | MW | 3 Sig Fig | |
| Hz | 0 dec places | N, N.m | 3 Sig Fig | |
| in, inHg, in^2 | 3 Sig Fig | ncm/h | 3 Sig Fig | |
| 3 Sig Fig | ppm | 3 Sig Fig | ||
| J/(kg.K) | 2 dec places | psi | 1 dec places | |
| kcal.m/h/(m^2.degC) | 3 Sig Fig | psi/ft | 3 Sig Fig | |
| kcal/(h.degC) | 3 Sig Fig | psi[g], psia | 4 Sig Fig | |
| kcal/(kg.degC) | 2 dec places | s | 0 dec places | |
| kcal/kg, kcal/m^3 | 3 Sig Fig | scm/h | 3 Sig Fig | |
| kg, kg.m/s, kg/(m.s^2) | 3 Sig Fig | SPG | 3 dec places | |
| kg.m^2 | 3 Sig Fig | tonne/h | 3 Sig Fig | |
| kg/cm^2, kg/cm^2/m | 3 Sig Fig | unitless | 3 Sig Fig | |
| kg/cm^2[a], kg/cm^2[g] | 4 Sig Fig | V, vol% | 3 Sig Fig | |
| kg/h | 0 dec places | W | 0 dec places | |
| kg/kmol | 1 dec places | W/(m.degC), W/(m^2.degC) | 3 Sig Fig | |
| kg/m, kg/m^2 | 3 Sig Fig | W/(m.K), W/(m^2.K) | 3 Sig Fig | |
| kg/m^3 | 4 Sig Fig | W/K, W/m^2 | 3 Sig Fig | |
| kgf/cm^2, kgf/m^2 | 3 Sig Fig | weight% | 3 Sig Fig |
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