An explosion can be defined as the sudden conversion of potential energy (chemical or mechanical) into kinetic energy with the production and release of gases under pressure, or the release of gas under pressure.  These high-pressure gases then do mechanical work such as moving, changing, or shattering nearby materials.

Once you complete the Week 6 readings, write a post to achieve the following:

1. Discuss the difference between a chemical and a mechanical explosion.
2. Discuss the difference between detonation and deflagration.
3. Research an explosion incident and then answers the following:
     A. Briefly discuss the incident.
     B. Was it a chemical or mechanical explosion?
     C. How much damage was created as a result of the explosion

#1

The difference between a chemical explosion and a mechanical explosion can be best described by giving examples of how the explosions occur.

A mechanical explosion happens when high pressure gas produces a physical reaction, vessel failure or rupture of the container. An example of a mechanical explosion can be the overloading of a container with compressed air. An example could be a tractor trailer container that would explode or an oxygen tank.

A chemical explosion is the result of a rapid chemical reaction that creates a significant amount of gas and/or heat. As we learned in the week 6 reading lessons chemical explosions can include solids, liquids, or gasses, which are mixed with an oxidizer for rapid reaction. Chemical explosions often happen in refineries that pipe in and store flammable liquids in storage tank farms.

The main difference between detonation and deflagration is that a deflagration occurs very slowly, slower than the local speed of sound while detonation occurs much faster at a supersonic speed of sound.

There was recently an explosion at a chemical plant in Port Neches, Texas on November 27, 2019. This explosion occurred at the TPC Group plant and was an example of a chemical explosion. The explosion caused significant structural damage to the plant and storage tanks. The local emergency services also issued a voluntary evacuation order for residents of Port Neches due to poor air quality that resulted from the explosion. The exact cause of this particular explosion is still under investigation by authorities from the plant owner itself and the local emergency authorities in Port Neches. It has been several years but in my response local we had a large oil storage tank explosion after the tank was struck by a lightning bolt during a severe thunderstorm.

Reference:

Adams-Heard, R. (2019). Still No “All Clear” After Chemical Blasts, But Town Moves on.    Bloomberg.com, The Guardian December 5, 2019 retrieved from “Theguardian.com”

#2

This week we are discussing an event that firefighter will largely react to in reaction state, rather then being on scene. While it is certainly possible to be on scene when there is a chemical or mechanical explosion more likely then not we will be dealing with the aftermath and the destruction that has resulted form the event. 

1. Discuss the difference between a chemical and a mechanical explosion.

A chemical explosion largely revolves around a chemical reaction of some sort. According to Keller these can include “Chemical changes such as rapid oxidation, deflagration or detonation, decomposition of molecules and runaway polymerization (usually detonations)” (Keller, 2014). A mechanical explosion is when container, such as “those in which a high pressure gas produces a physical reaction, vessel failure or rupture of the container” (Keller, 2014)

2. Discuss the difference between detonation and deflagration.

Detonation according to the Bradbury Science Museum is “the initiator for this process, or detonator, is most often electrical or mechanical in nature but chemical versions aren’t uncommon” (Bradbury, 2018). On the other hand the deflagration is the actual subsonic combustion that occurs as a result of the detonation and the chemical or mechanical reaction within the explosive.

3. Research an explosion incident and then answers the following:

     A. Briefly discuss the incident.

One of the most well known incidents is the Oklahoma City Bombing

     B. Was it a chemical or mechanical explosion?

The event was a chemical explosion

     C. How much damage was created as a result of the explosion

The explosion occurred in 1995 and resulted in 680 or more injuries. The Alfred P. Murrah Federal Building itself also suffered extensive damage. 

References:

Department of Energy. (2018). What’s the difference between an explosion and a detonation? Retrieved from https://www.lanl.gov/museum/news/newsletter/2018/08/detonation.php

Keller, J. O., Gresho, M., Harris, A., & Tchouvelev, A. V. (2014). What is an explosion?. International Journal of Hydrogen Energy, 39(35), 20426-20433.