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
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
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
Read MoreKey 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
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
Read MoreAtomic 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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