The fire triangle is a useful teaching tool, but fails to identify the fourth essential element of fire: the sustaining chemical reaction. This has led to development of the fire tetrahedron: a triangular pyramid having four sides (including the bottom). In most fires it simply doesn’t matter which element gets removed; the fire fails to ignite, or it goes out. However, there are certain chemical fires where knowin ...

See also:

Fire triangle, Fire triangle - Fire tetrahedron

Read more here: » Fire triangle: Encyclopedia II - Fire triangle - Fire tetrahedron

Air is the most common and only natural breathing gas. Other artificial gases, either pure gases or mixtures of gases, are used in enclosed breathing environments such as SCUBA equipment, recompression chambers, submarines, space suits and anaesthetic machines. A safe breathing gas has three essential features: it must contain sufficient oxygen to support the life, consciousness and work rate of the breather. it must not contain harmful gases. Carbon monoxide and carbon dioxide are common poisons in ...

Including:

• Breathing gas - Common diving breathing gases
• Breathing gas - Individual component gases
• Breathing gas - Oxygen
• Breathing gas - Nitrogen
• Breathing gas - Helium
• Breathing gas - Neon
• Breathing gas - Hydrogen
• Breathing gas - Unwelcome components of breathing gases
• Breathing gas - Argon
• Breathing gas - Carbon dioxide
• Breathing gas - Carbon monoxide
• Breathing gas - Hydrocarbons
• Breathing gas - Moisture content
• Breathing gas - Gas detection and measurement

Read more here: » Breathing gas: Encyclopedia - Breathing gas

Aerogel is a solid-state substance similar to gel where the liquid component is replaced with gas. The result is an extremely low density solid with several remarkable properties, most notably its effectiveness as an insulator. It is nicknamed frozen smoke, solid smoke or blue smoke due to its semi-transparent nature; however it feels like foam to the touch. Aerogel was first created by Steven Kistler in 1931, as a result of a bet with Charles Learned over who could replace the liquid inside a jelly jar wit ...

Including:

• Aerogel - Properties
• Aerogel - Silica aerogel
• Aerogel - Uses
• Aerogel - Production

Read more here: » Aerogel: Encyclopedia - Aerogel

Arc welding refers to a group of welding processes that use a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is sometimes protected by some type of inert or semi-inert gas, known as a shielding gas, and/or filler material. Arc welding - Development. While examples of welding go back to the Bronze Age a ...

Including:

• Arc welding - Development
• Arc welding - Power supplies
• Arc welding - Consumable electrode methods
• Arc welding - Non-consumable electrode methods
• Arc welding - Corrosion issues
• Arc welding - Safety issues

Read more here: » Arc welding: Encyclopedia - Arc welding

Welding is a fabrication process that joins materials, usually metals or thermoplastics, by causing coalescence. This is often done by melting the workpieces and adding a filler material to form a pool of molten material that cools to become a strong joint, but sometimes pressure is used in conjunction with heat, or by itself, to produce the weld. This is in contrast with soldering and brazing, which involve melting a lower-melting-point material between the workpieces to form a bond ...

Including:

• Welding - History
• Welding - Welding processes
• Welding - Arc welding
• Welding - Gas welding
• Welding - Resistance welding
• Welding - Energy beam welding
• Welding - Solid-state welding
• Welding - Geometry
• Welding - Quality
• Welding - Heat-affected zone
• Welding - Distortion and cracking
• Welding - Weldability
• Welding - Unusual conditions
• Welding - Safety issues
• Welding - Costs and trends
• Welding - Notes

Read more here: » Welding: Encyclopedia - Welding

Inerting systems have been used in military aircraft starting with a 1950 version of the United States' B-47 bomber jet, which sublimated dry ice to produce gaseous carbon dioxide and pump it into the fuel tanks whenever the fuel pumps were active or whenever in-flight refueling was in process. This system was implemented largely over concern over static electricity discharges during in-flight refu ...

See also:

Inerting system, Inerting system - Use in military aircraft, Inerting system - Use in commercial aircraft after Flight 800

Read more here: » Inerting system: Encyclopedia II - Inerting system - Use in military aircraft

Ferrocene undergoes many reactions characteristic of aromatic compounds, notably Friedel-Crafts reactions. In an illustrative undergraduate experiment, ferrocene is acetylated upon treatment with acetic anhydride and phosphoric acid. Ferrocene is readily deprotonated, e.g. by butyl lithium, to give 1,1'-dilithioferrocene, which in turn is a versatile nucleophile. Unlike related organic compounds, ferrocene has one very special property - the ability to undergo one-electron oxidation at mild potentials. Oxidation is usually cond ...

See also:

Ferrocene, Ferrocene - Physical Properties, Ferrocene - Chemical Properties, Ferrocene - Applications, Ferrocene - External link

Read more here: » Ferrocene: Encyclopedia II - Ferrocene - Chemical Properties

In the late 1970s and early 1980s, the need for alternative storage began to grow when pools at many nuclear reactors began to fill up with stored spent fuel. As there was not a national storage facility in operation (Yucca Mountain was, and remains, embroiled in controversy), utilities began looking at options for storing spent fuel. Dry cask storage was one of the most practical options for temporary storage. The first dry storage installation was licensed by the Nuclear Regulatory Commission in 1986 at the Surry Nuclear Power Plant ...

See also:

Dry cask storage, Dry cask storage - History

Read more here: » Dry cask storage: Encyclopedia II - Dry cask storage - History

Potentiostatic coulometry techniques have been used to determine over 50 elements. They are used very frequently for the determination of uranium and plutonium since potentiostatic coulometry techniques do not interfere much with the sample. Another useful application is the determination of the amount of oxygen in a sample by using a cadmium electrode and a porous silver electrode. This system for determining oxygen is convenient because it does not require an external power supply or a potentiostat to control the reaction since it does not ...

See also:

Coulometry, Coulometry - Potentiostatic coulometry, Coulometry - Coulometric titration, Coulometry - Applications, Coulometry - Karl Fischer reaction, Coulometry - Determination of Film Thickness, Coulometry - Coulometers, Coulometry - Electronic coulometer, Coulometry - Electrochemical coulometers

Read more here: » Coulometry: Encyclopedia II - Coulometry - Applications

Welding - Arc welding. Arc welding processes use a welding power supply to create and maintain an electric arc between an electrode and the base material to melt metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is sometimes protected by some type of inert or semi-inert gas, known as a shielding gas, and fille ...

See also:

Welding, Welding - History, Welding - Welding processes, Welding - Arc welding, Welding - Gas welding, Welding - Resistance welding, Welding - Energy beam welding, Welding - Solid-state welding, Welding - Geometry, Welding - Quality, Welding - Heat-affected zone, Welding - Distortion and cracking, Welding - Weldability, Welding - Unusual conditions, Welding - Safety issues, Welding - Costs and trends, Welding - Notes

Read more here: » Welding: Encyclopedia II - Welding - Welding processes

A protection relay is a complex electromechanical apparatus, often with more than one coil, designed to calculate operating conditions on an electrical circuit and trip circuit breakers when a fault was found. Unlike switching type relays with fixed and usually ill-defined operating voltage thresholds and operating times, protection relays had well-established, selectable, time/current (or other operating parameter) curves. Such relays were very elaborate, using arrays of induction disks, shaded-pole magnets, operating and restraint c ...

See also:

Relay, Relay - Operation, Relay - Types of relay, Relay - Applications, Relay - Relay application considerations, Relay - Protection relay

Read more here: » Relay: Encyclopedia II - Relay - Protection relay

Decompression sickness can happen in any of the following situations: A diver ascends from a dive. An unpressurized aircraft flies upwards. The cabin pressurization system of an aircraft fails. Divers flying in any aircraft after diving. Pressurized aircraft are not risk-free, since the cabin pressure is not maintained at sea-level pressure. A worker comes out of a pressurized caisson, or out of a mine, which has been pressurized to keep water out. This causes inert gases (mainly nitrogen), normally dissolved in body fluids and tissues, to ...

See also:

Decompression sickness, Decompression sickness - Introduction, Decompression sickness - History, Decompression sickness - Predisposing factors, Decompression sickness - Signs and symptoms, Decompression sickness - Treatment, Decompression sickness - Common pressure reductions that cause DCS, Decompression sickness - Leaving a high pressure environment, Decompression sickness - Ascent during a dive, Decompression sickness - Ascent to altitude

Read more here: » Decompression sickness: Encyclopedia II - Decompression sickness - Introduction

The reactor provides heat, which is used to turn a generator. However, there are a number of different design choices. The uranium, thorium or plutonium nuclear fuels are in the form of a ceramic (usually oxides or carbides) contained within spherical pebbles made of pyrolytic graphite (see discussion below). The pebbles are in a bin or can. An inert gas, helium, nitrogen or carbon dioxide, circulates through the spaces between th ...

See also:

Pebble bed reactor, Pebble bed reactor - Basic design, Pebble bed reactor - Stationary designs and history, Pebble bed reactor - Mobile power systems, Pebble bed reactor - Safety Features, Pebble bed reactor - Containment, Pebble bed reactor - Production of Fuel, Pebble bed reactor - Criticism

Read more here: » Pebble bed reactor: Encyclopedia II - Pebble bed reactor - Basic design

There are a variety of tasks for which aerogels are used. Commercially, aerogels have been used in granular form to add insulation to skylights. After several trips on the Vomit Comet, one research team has shown that producing aerogel in a weightless environment can produce more uniform size of the particles, and reduce this Rayleigh scattering effect in silica aerogel, thus making the aerogel less blue and more transparent. Transparent silica aerogel would be very suitable as a thermal insulation material for windows, significantly limit ...

See also:

Aerogel, Aerogel - Properties, Aerogel - Silica aerogel, Aerogel - Uses, Aerogel - Production

Read more here: » Aerogel: Encyclopedia II - Aerogel - Uses

The PCB will then enter the fluxing zone, which applies flux to the underside of the board. Two types of fluxers are used: the spray fluxer and foam fluxer. Wave soldering - Spray fluxer. The spray fluxer consists of a robotic arm which travels from side to side while spraying a fine mist of flux onto the bottom side of the board. Some systems will then use compressed air to remove excess flux or to completely remove flux from some areas. See also:

Wave soldering, Wave soldering - Wave Solder Process, Wave soldering - Fixtures, Wave soldering - Fluxing, Wave soldering - Spray fluxer, Wave soldering - Foam fluxer, Wave soldering - Preheating, Wave soldering - Soldering, Wave soldering - Cleaning, Wave soldering - Process monitoring

Read more here: » Wave soldering: Encyclopedia II - Wave soldering - Fluxing

While examples of welding go back to the Bronze Age and the Iron Age, arc welding did not come into practice until much later. In 1800, Sir Humphrey Davy discovered the electric arc, initiating the development of arc welding which continued with the inventions of metal electrodes by a Russian (N.G. Slavianoff) and an American (C.L. Coffin) in the late 1800s even as carbon arc welding, which used a carbon electrode, gained popularity. Around 1900, A. P. Strohmenger released in Britain a coated metal electrode which gave a more stable arc. In 1919, alternating current welding was invented by C.J. Holslag but ...

See also:

Arc welding, Arc welding - Development, Arc welding - Power supplies, Arc welding - Consumable electrode methods, Arc welding - Non-consumable electrode methods, Arc welding - Corrosion issues, Arc welding - Safety issues

Read more here: » Arc welding: Encyclopedia II - Arc welding - Development

Breathing gas - Oxygen. Oxygen (O2) must be present in every breathing gas. This is because it is essential to the human body's metabolic process, which sustains life. The human body cannot store oxygen for later use as it does with food. If the body is deprived of oxygen for more than a few minutes, unconsciousness results. The tissues and organs within the body (notably the heart and brain) are dama ...

See also:

Breathing gas, Breathing gas - Common diving breathing gases, Breathing gas - Individual component gases, Breathing gas - Oxygen, Breathing gas - Nitrogen, Breathing gas - Helium, Breathing gas - Neon, Breathing gas - Hydrogen, Breathing gas - Unwelcome components of breathing gases, Breathing gas - Argon, Breathing gas - Carbon dioxide, Breathing gas - Carbon monoxide, Breathing gas - Hydrocarbons, Breathing gas - Moisture content, Breathing gas - Gas detection and measurement

Read more here: » Breathing gas: Encyclopedia II - Breathing gas - Individual component gases

Coulometric titrations use a constant current system to perform the reaction. The only measurements required in these systems is the time it takes to complete the electrolysis. The product of this time and the current is then used to determine the total amount of electricity used. The endpoint of the titration can be determined analytically by using an indicator that is placed in the sample and signals when the system reaches equilibrium. Alternatively, the endpoint can be determined from data provided by potentiometric, amperometric or conductance measureme ...

See also:

Coulometry, Coulometry - Potentiostatic coulometry, Coulometry - Coulometric titration, Coulometry - Applications, Coulometry - Karl Fischer reaction, Coulometry - Determination of Film Thickness, Coulometry - Coulometers, Coulometry - Electronic coulometer, Coulometry - Electrochemical coulometers

Read more here: » Coulometry: Encyclopedia II - Coulometry - Coulometric titration

Potentiostatic coulometry involves keeping the electrochemical potential at the working electrode (the electrode involved in the reaction) constant, which results in an exponential decrease in current as the reaction proceeds. This is because the potential at the working electrode is not equal to the potential of the entire cell. It is related by the equation: where R is the gas constant, n is the stoichiometric number of electrons, and See also:

Coulometry, Coulometry - Potentiostatic coulometry, Coulometry - Coulometric titration, Coulometry - Applications, Coulometry - Karl Fischer reaction, Coulometry - Determination of Film Thickness, Coulometry - Coulometers, Coulometry - Electronic coulometer, Coulometry - Electrochemical coulometers

Read more here: » Coulometry: Encyclopedia II - Coulometry - Potentiostatic coulometry

Some types of flux, called "no-clean" fluxes, do not require cleaning; their residues are benign after the soldering process. Others, however, require a cleaning stage, in which the PCB is washed with solvents and/or deionized water to remove flux residue. ...

See also:

Wave soldering, Wave soldering - Wave Solder Process, Wave soldering - Fixtures, Wave soldering - Fluxing, Wave soldering - Spray fluxer, Wave soldering - Foam fluxer, Wave soldering - Preheating, Wave soldering - Soldering, Wave soldering - Cleaning, Wave soldering - Process monitoring

Read more here: » Wave soldering: Encyclopedia II - Wave soldering - Cleaning