What is a Flame Safety Lamp?

What is a Flame Safety Lamp?

A flame safety lamp is a lighting device which was used in places, like mines, where there is danger from the explosion of combustible gasses. It is an example of how scientific knowledge and research could be applied to practical work to improve, and even save, lives.

Until the invention of this lamp, miners had to carry open flames into coal mines where firedamp (an explosive mixture of methane and carbon dioxide) often caused deadly explosions. The flame safety lamp was the first device to allow the use of an open flame safely, thus dramatically increasing the amount of work that could be done in mines and enabling deeper mining.

The flame safety lamp works by encapsulating the flame in a wire gauze cylinder which prevents the methane gases from escaping and igniting. There are various versions of the lamp but all have a similar design. The outer cylinder is cooled with water to help the wick burn, while the inner cylinder is lined with a mesh of fine wires which prevents the methane gases from passing through and igniting the flame of combustion. Often the gauze is made of iron or steel and it is fine enough to be able to see through. A miner could detect the presence of methane by watching how the flame behaved in different conditions.

This is a permissible flame safety lamp which means it has passed a series of tests conducted by the U.S. Department of the Interior Bureau of Mines. These tests are designed to ensure the lamp is safe to use in gassy mines. The lamp employs the same general construction as the original flame safety lamps developed by Sir Humphrey Davy in 1815. There are a few minor variations in the details such as the shape of the Pyrex enclosure, the mesh upper interior to cool the flame and the metal bonnet exterior to better protect the lamp from extinguishing in gusts or drafts common in mines.

Davy’s lamp was a significant advance over the previous devices which had been in use but suffered from problems such as fragility and lack of stability. Davy himself was aware of these issues but declined to patent his device turning down the chance to make a fortune stating - 'My sole object is to serve the cause of humanity.'

Other inventors of flame safety lamps such as William Reid Clanny and George Stephenson improved upon the original Davy lamp. Most of the lamps in the collection of the Division of Work and Industry include contributions from all three inventors – Davy’s glass enclosure, Clanny’s water seals, and Stephenson’s metal enclosure. The collection also includes several examples of the earliest types of lamps which employed a bellows to supply oxygen, an arrangement which proved less efficient than the current rebreather system which is now used in many mines. The lamps were collected every day from the lamp room and refuelled, cleaned and inspected between shifts. The lamp was locked to prevent it from being exposed to the inflammable atmosphere of the mine and allowed to be opened only for inspection.