History Matters: Fire Extinguishers

In the Middle Ages, Ctesibius’ technique was adapted to the “squirt,” a device that siphoned water from a tank through a nozzle and then shot it at the fire by pushing home a plunger, like a bicycle pump. Squirts were used to fight the Great Fire of London in 1666, albeit not very effectively.

But fire extinguishing didn’t advance much beyond pumps and bucket brigades until 1723, when English chemist Ambrose Godfrey patented an explosive alternative. His invention used a cask of fire-suppressing liquid that was released by the blast of a pewter chamberful of gunpowder. Besides scattering the liquid, the explosion probably helped blow out the fire like puffing out a candle. Godfrey’s device was successfully used to put out a London fire in 1729.

Complicating efforts to further the technology of fire extinguishing, though, was a lack of understanding of exactly how fire worked and what it really was. Even as late as the 17th century, the combustion process was thought to involve a spiritual substance dubbed “phlogiston.” Not until 1778, when the French chemist Antoine Lavoisier discovered oxygen, did science explain the chemical reaction that enables fire.

That breakthrough paved the way for what’s considered the first modern fire extinguisher, which British Capt. George William Manby patented in 1818. No jubilees will mark the 250th anniversary of Manby’s birth in 2015, but he was a fellow worth celebrating. His passion for public safety was first aroused as a young militiaman, when he was appointed barrack-master at Great Yarmouth, England. There in 1807, he witnessed a fierce storm that drowned dozens of men, women and children in a vessel only 60 yards offshore; helpless onlookers on land could do nothing. The tragedy inspired Manby to invent the Manby Morter, a device that fired a rope from the shore to a ship, where it could be attached and used to guide lifeboats to safety. The morter proved its worth in 1808, when the inventor used it to rescue sailors from a boat 150 yards out at sea. Dozens of the devices were subsequently installed along the coast.

Manby also invented an apparatus for rescuing people who’d fallen through ice and a way of safely catching people jumping from burning buildings. His “unsinkable” lifeboat proved less successful, as Manby himself had to be rescued from it as it sank.

He’s best known, however, for his Extincteur, which consisted of a 3-gallon copper container filled with a pearl-ash (potassium carbonate) solution. Compressed air propelled the chemical onto a fire. A similar system is still used today in condensed aerosol fire suppressants, which work in part by inhibiting the chemical reactions of combustion.
French inventor François Carlier eliminated the need for compressed air in a fire extinguisher in 1866, with his soda-acid version. By mixing tartaric acid with a solution of water and sodium bicarbonate (baking soda), Carlier’s invention created carbon dioxide gas and provided its own propellant. A similar scheme was patented in the United States in 1881 by Almon M. Granger, who replaced the tartaric acid with a vial of sulphuric acid. In the event of a fire, the vial would be broken open with a plunger or, in an alternate design, by removing a lead stopper. (A similar system is still used in cartridge-operated extinguishers.)

Gunpowder and acid were hardly the only dangerous materials employed in fire extinguishers, however. In 1910, the Delaware-based Pyrene Manufacturing Co. patented a fire extinguisher filled with carbon tetrachloride. The chemical vaporized into a blanketing fog and deprived the flames of oxygen, as well as inhibiting combustion reactions. A portable, hand-pumped version made of brass or chrome was introduced the following year; it could even be refilled through a filling plug. Carbon tetrachloride extinguishers became
particularly popular in those newfangled automobiles filling—and occasionally catching fire on—the nation’s byways.

Carbon tetrachloride was also the fire-suppressing agent in the “fire grenade,” which was designed to be hurled at the base of the fire rather than spraying the flames. Early grenades were simply water-filled glass bottles, but carbon tetrachloride proved far more effective.

Unfortunately, in high concentrations, carbon tetrachloride also turned out to damage the nervous system and internal organs. When sprayed on a fire, moreover, it turns into phosgene gas—an infamous chemical weapon used in World War I. Fire extinguishers stopped using carbon tetrachloride in the 1950s, after these downsides were discovered.

Efforts to fight fires without employing acid or deadly chemicals at first focused on simple metal cylinders filled with carbon dioxide already in gaseous form. The Walter Kidde Co. developed the first carbon-dioxide extinguisher in 1924, to meet the need for a fire-suppressing spray that didn’t conduct electricity—important to Bell Telephone, which had been plagued by fires in telephone switchboards. Carbon dioxide could also be sprayed on people who were on fire, such as Hollywood stuntmen, and is still employed in movies and TV production.

Foam was an even better medium for fighting fires, but tricky and expensive to produce. Organic raw materials, such as animal hooves or horns, or licorice root, outperformed chemical agents, but were impractical for mass manufacture. During World War II, Percy L. Julian developed a method for creating foam from soy protein. The US military adopted his Aero Foam extinguishers; they later found their way into civilian use.

Timeline

200 BCE | Greek barber Ctesibius creates a hand pump for spraying water

1666 | “Squirts” are used against the Great Fire of London

1723 | Ambrose Godfrey patents a gunpowder-based extinguisher