19 June 2023
It sounds incredible, but glass grenades were once a standard way of putting out fires. Sharing some examples from the London Fire Brigade Museum Paul Chiddicks tells us more...
Colourful glass fire grenades were first introduced in the 19th century. They were produced as decorative glass bottles with a bulbous bottom, long neck and usually patterned with the company name on them. Branded examples included the Harden Star Grenade and the Swift Fire Grenade.
The oldest glass fire grenade in the London Fire Brigade Museum’s collection dates from c.1880. There were two main methods of using them; either by picking them up and throwing them at the base of a fire, or in larger homes and workplaces, they were suspended from the ceiling in special brackets. In this case the heat would cause wax parts to melt or the glass to break, and a deflection component would distribute the liquid contents like a form of sprinkler.
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The grenades were filled with salt water, a mix of common table salt and ammonium chloride, until about 1900, when they were filled with carbon tetrachloride, sometimes called carbon tet, or CTC. This is a liquid at room temperature but when heated to about 76oC becomes a gas. The gaseous carbon tetrachloride has a higher density than air so it sinks and helps smother the flames. However, it was later discovered that carbon tetrachloride is harmful to humans, and as a result many companies then went back to using the salt solutions in the 1950s.
Fire grenade thought to be of French origin
After the installation of more reliable modern sprinkler systems, the use of glass fire grenades was phased out, although some examples can still be seen in place in historic buildings, for example salt solution filled Harden Star Grenades at Erddig, Wales, cared for by the National Trust.
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The museum also has a Twitter account - @LFBMuseum - where other updates and insights into their history and stories are shared.
About the author
Paul Chiddicks is the author of the regular 'Dear Paul' column in Family Tree magazine. You can read his latest column in the June 2023 issue.
Images copyright London Fire Brigade Museum