Fire Extinguisher Types and Their Limitations

1. Limitations of Foam Extinguishers

  • In electrical fires, water content poses a risk to personnel due to conductivity, especially in manual applications. Automatic systems are more effective than water alone.
  • Incompatibility between some foams and powder extinguishers can cause foam breakdown when applied simultaneously, particularly with obstacles on the burning liquid’s surface.
  • Not suitable for pressurized gas fires (butane, propane, etc.) due to high evaporation and swelling.
  • Reacts with highly
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Essential Vocabulary: Definitions and Synonyms

Vocabulary Definitions and Equivalents

Golden Age
Period of great cultural flourishing.
Anything but
Definitely not.
Discovery
Act of finding.
To sustain
To support.
To lay the foundation for
Set the conditions for something.
Daily
Every day.
Soap
A substance used for washing.
To stretch
Spread out, expand.
Border
Frontier line.
At the height of
At the most advanced or intense point.
Massive
Huge.
To fuel
Give energy to; encourage.
Growth
Increase in size.
From far and wide
From everywhere; from many different places.
Trade
Exchange
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Confined Spaces: Hazards, Risks, and Safety Measures

Confined Spaces: Definition and Examples

A confined space is any space with limited openings for entry and exit, where an employee can fully enter. These spaces often have unfavorable natural ventilation, allowing pollutants to accumulate, creating toxic, flammable, or oxygen-deficient atmospheres. Confined spaces are not designed for continuous human occupancy.

NIOSH Definition of Confined Space

The National Institute for Occupational Safety and Health (NIOSH) defines a confined space as any space

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Key Chemistry Concepts and Formulas

Conversions

  • Celsius to Fahrenheit: F = (9/5) * C + 32
  • Celsius to Kelvin: K = C + 273

Atomic Structure

  • Atomic Mass: Protons + Neutrons (upper left symbol)
  • Atomic Number: Protons (bottom left symbol)

Constants

  • Planck’s Constant (h): 6.6260755 x 10-34 J*s

Photons

  • Energy of a Photon: E = hv or E = hc / wavelength

Electronic Transitions

  • Absorption: When energy is absorbed by the hydrogen atom, the electron is excited to a higher energy level or orbital.
  • Emission: When the electron relaxes from a higher energy orbital
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Chemical Bonds: Polarity, Metallic & Intermolecular Forces

Polar Covalent Bonds and Polarity

Polarization of Bonds: A polar bond forms when two atoms with different electronegativity come together. This results in partial charges appearing at the ends of the bond. A bond is more polarized the greater the difference in electronegativity between the two atoms. This difference indicates the percentage of ionic character in the covalent bond.

Polar Molecules

A diatomic molecule is polar if its bond is polarized. For a polyatomic molecule to have a molecular dipole

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Atomic Structure, Chemical Bonding, and Solutions

Elements and Atoms

An element is a pure substance that cannot be broken down into simpler substances.

An atom is the smallest part of an element that has all the properties of that element.

Atomic Structure

Atoms have a very dense center called the nucleus. The nucleus is made up of protons and neutrons.

  • Protons are positively charged (+).
  • Neutrons are neutral (no charge).
  • Electrons are negatively charged (-).

You can tell how many protons an atom has by looking at the periodic table (the atomic number

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