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Chemical Fire Engines

Updated: Jun 25, 2022

Chemical fire engines once were an important part of the American fire service. From the 1880s until the 1930s, fire engines equipped with soda-acid “chemical” tanks served in communities of all sizes. Chemical fire engines came in many different types and sizes and were built as hand- and horse-drawn. Later, they would be built in a variety of motorized configurations.

Soda-acid chemical systems for firefighting were developed in the 1860s and 1870s. These systems relied upon a chemical reaction to create pressure that would force water out of a tank and through a hose. These systems typically consisted of a copper tank in which there was a mixture of soda water. This was water to which sodium bicarbonate, better known as baking soda, was added. Within the tank, a powerful acid, like sulfuric acid, was held in a glass jar.

When it was time to use the chemical system, a lever was used to break the glass jar. This would release the acid into the soda water. This would initiate a chemical reaction that would release carbon dioxide gas. This reaction would create pressure, which in turn would force water out of the tank.

Connected to the tank was a rubber hose, with a diameter slightly larger than a modern garden hose. This hose was carried in a wire hose basket or on a hose reel. The length of the hose varied between 100 and 200 feet depending on the make and model of the chemical engine.

This technology was used for handheld fire extinguishers, which typically carried a couple of gallons of water. These had the acid in a glass jar at the top of the cylinder. To use the extinguisher, the user would turn the extinguisher upside down. This let the acid pour out into the soda water and create the chemical reaction.

Large extinguishers with were mounted on wheels. Initially, when chemical tanks were mounted on wheels this was called a chemical cart. Eventually these would be called chemical engines. These tanks typically varied from 35 to 60 gallons in capacity. Chemical engines could be deployed very quickly at a fire. They proved to be very effective on small incipient fires.

The first chemical fire apparatus was the “fire extinguisher wagon” that went into service in 1871 in Boston. It carried ten hand fire extinguishers. It was assigned to Extinguisher Company No. 1. The next year, two larger “fire extinguisher wagons,” with 25 extinguishers each, entered service. Eventually these companies evolved into chemical companies and had horse-drawn chemical engines starting in 1873.

In 1872, Chicago became the first fire department to operate horse-drawn chemical engine. This was built by the Babcock Manufacturing Company of Chicago. Babcock was the first American builder of chemical fire engines in America.

As these systems became larger, they were mounted on horse-drawn four wheeled chassis. Some of the largest horse-drawn chemical engines carried a pair of 80- or 90-gallon tanks. Most carried smaller 40- or 50-gallon tanks.

Among the most popular types of chemical fire engines were made by the Charles T. Holloway Company of Baltimore, Maryland. Horse-drawn Holloway chemical engines typically carried their chemical tanks upright. Most other types of chemical engines carried their tanks horizontally.

Eventually chemical tanks were mounted on hose wagons. The resulting apparatus were called a combination chemical fire engine hose wagon, which often was shortened simply to a “combination wagon. “ These were extremely common in communities of every size. They could operate by themselves or they could be paired with a steam fire engine.

Very often chemical tanks were mounted in pairs to allow continuous operation. The second tank could be used after the first was exhausted. While the second tank was being used, the first tank could be refilled and recharged to be ready to operate again when the second tank ran out. This required adding fresh water and the soda solution as well as loading another acid bottle.

According to several studies of American fire departments that were conducted around 1900, chemical engines were used to extinguish about 75 to 85 percent of fires. Although chemical systems were very effective on small fires, chemical engines were not very effective of larger fires, they still were useful with large fires because they could go into action faster than steamers. Often chemical engines were used for initial fire attack until the steamers could get up enough pressure to operate. For this reason, many steam fire engines operated as a two-piece engine company with a combination chemical engine hose wagon rather than just a regular hose wagon.

Chemical fire engines were relatively safe for the time, although they are far too dangerous by today's standards. Once the chemical reaction started, pressure in the chemical tank would build up and had to be released promptly. If it was not, the tank could burst. Chemical engines therefore were brought to the scene of the fire before the soda and acid were mixed to avoid a premature and possible catastrophic build-up of pressure.

Many communities operated chemical engine companies with a horse-drawn chemical engine. Like hose wagons, chemical engines came in many different configurations and sizes. Some chemical engines carried ladders. Some had turret nozzles. Most horse-drawn chemical engines had two chemical tanks and around 200 feet of one-inch rubber hose. Some were much larger.

Despite the popularity of combination wagons, straight horse-drawn chemical engines still were built until the adoption of motorized fire apparatus. Even after motor fire apparatus began to proliferate, many horse-drawn chemical engines remained in service and others were remounted on an automobile or light truck chassis.

The first motorized fire apparatus were built in the first decade of the 20th Century. These initially included chemical engines as well as combination wagons. Like the horse-drawn apparatus that they replaced, motor chemical engines and combination wagons came in a wide variety of configurations and sizes. Boston was the first New England community to use a motor chemical engine when it evaluated a prototype model that was loaned to the city by the American-LaFrance Fire Engine Company in the fall of 1906.

Early automobiles and trucks were more powerful and had far greater endurance and range than horses. This allowed for larger and more capable apparatus to be built. Chemical engine hose wagons combinations were the most popular of early motor fire apparatus. Motor chemical engines and combination wagons were built by every major manufacturer of fire apparatus as well as many smaller firms.

The greater power of motor apparatus allowed for larger chemical engines to be built. Some of these had three, four and even six chemical tanks. With tanks being operated in pairs, chemical engines with four or six tanks could have two or three chemical hose lines in operation at one time.

Eventually as more powerful and capable motor vehicles were developed, a chemical tank or two would be mounted on a pumping engine. These were called triple combinations. A triple combination could replace two pieces of apparatus and required less firefighters to operate. Triple combinations became very popular starting in the 1920s. In the late 1920s, some triple combinations were built with water tanks that were connected to their pump. These “booster” tanks were easier to operate with and safer than chemical tanks. Over the course of the early 1930s booster tanks would replace chemical tanks on fire apparatus. Hand-held soda acid fire extinguishers would continue to be used for a few more decades.


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