Extreme Analysis

The program

 

This is a program created by 3 students from Singapore Polytechnic as part of their Final Year Project. The calculator was programmed using Microsoft Excel’s Visual Basic for Applications. 

 

Functions

 

• Able to perform Blast Overpressure calculations with:

 

- Known distance from centre of explosion

 

> Desired distance is to be keyed in. Blast overpressure at the stated distance will be calculated. This is to obtain the value of the blast overpressure that would be felt at the stated distance.

> A list of damages which would be dealt at the stated distance will be provided.

 

- Known blast overpressure

 

> Identified blast overpressure is to be keyed in. Distance from the centre of explosion which would be affected by the stated overpressure is calculated. This will allow you to identify critical distances where a certain blast overpressure would be felt.

> A list of damages which would be dealt at the calculated distance will be provided.

 

• Able to perform Thermal Radiation Intensity calculations with:

 

- Known distance from centre of explosion

 

> Desired distance is to be keyed in. Thermal radiation intensity at the stated distance will be calculated. This is to obtain the value of the thermal radiation intensity that would be felt at the stated distance.

> Blast fireball radius and duration would also be calculated.

> Time till severe pain is felt and second degree burns are caused at the stated distance will be provided.

 

- Known thermal radiation intensity

 

> Identified thermal radiation intensity is to be keyed in. Distance from the centre of explosion which would be affected by the stated thermal radiation intensity is calculated. This will allow you to identify critical distances where a certain thermal radiation would be felt.

> Blast fireball radius and duration would also be calculated

> Time till severe pain is felt and second degree burns are caused at the calculated distance will be provided.

 

• In-built volume to mass converter

 

• User-friendly interface

 

- Terms required at each textbox is explained by hovering mouse over textbox heading

- Values calculated is explained by hovering mouse over textbox heading

 

Equations Used

 

Blast overpressure

 

- Equivalent Mass of TNT, mTNT

 

 

 

 

 

- Scaled Distance, Ze

 

 

 

 

 

- Scaled Overpressure, Ps

 

 

 

 

 

 

 

- Peak Overpressure, Po

 

 

 

Where

 

mTNT is the equivalent mass of TNT

μ is the explosion efficiency

m is the mass of fuel involved (kg)

△Hc is the energy of explosion of the gas (MJ/kg)

ETNT is the energy of explosion of TNT (MJ/kg)

Ze is the scaled distance (m/kg^1/3)

r is the distance from center of explosion (m)

Ps is the scaled overpressure

Po is the peak overpressure (psi)

Pa is the ambient pressure (psi)

 

Obtained from “Guidelines for Chemical Process Quantitative Risk Analysis, Second Edition, by Center for Chemical Process Safety (CCPS)”

 

Thermal Radiation Intensity

 

- Thermal Radiation Intensity

 

 

 

 

- Duration of Fireball

 

 

 

- Radius of Fireball

 

 

 

Where

 

ItA is the actual thermal radiation intensity (kW/m^2)

Rt is the distance from fireball to the target (m)

Et is the heat Released (J)

Fr is the fraction of heat radiated

M is the mass of chemical entering fireball (ton)

D is the duration of fireball (s)

R is the radius of fireball (m)

 

Obtained from "Lees’ Loss Prevention in the Process Industries, Volumes 1-3 - Hazard Identification, Assessment and Control (4th Edition)"

 

Guide to using the program

 

For users using Microsoft Excel 2013 version, an additional step is required before opening the software.

 

Additional step for Microsoft Excel 2013 users:

 

1. Open Microsoft Excel

 

2. Navigate to "File"

 

3. Under "File", click on "Options". A pop-out should appear

 

4. Navigate to the "Add-Ins" tab

 

5. Click on "Go" after changing the "Manage" to "Excel Add-Ins"

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6. Ensure that there is a "Tick" in the box beside "Solver Add-In". Advance by clicking on "ok". After this has been       done, you may proceed to opening up the downloaded file and follow the software guide.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Guide to using the Calculation Software:

 

1. Upon opening up the downloaded file for the first time, you will be greeted by these messages:

 

 

Click “Enable Editing”. This is to allow you to start using our program. The program should automatically run once editing has been enabled.

Note: There might be another message asking for permission to “Enable Macro”, you have to click it also.

 

2. This is the main page of the program

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Click on the desired calculations that you want to make.

 

3. Blast Overpressure Calculations

 

 

 

 

 

 

 

 

 

 

 

 

 

Select the value which is known by you.

               

- For example, “Distance from center of explosion is known” is clicked.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

                               

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Enter the required values. For any uncertainties, hover your mouse over the textbox headings to get a more detailed explanation of the required values.

 

- Click on “Calculate” once the required values have been entered. The results would then appear.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

4. Thermal Radiation Intensity Calculations

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Select the value which is known by you.

 

- For example, “Thermal radiation intensity is known” is clicked.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Enter the required values. For any uncertainties, hover your mouse over the textbox headings to get a more detailed explanation of the required values.

 

- Click on “Calculate” once the required values have been entered. The results would then appear.