This section is from the book "The Principles And Practice Of Modern House-Construction", by G. Lister Sutcliffe. Also available from Amazon: How Your House Works: A Visual Guide to Understanding & Maintaining Your Home.
One of the most frequent causes of explosion is the faulty gas-tap. All these taps have a small pin or stop inserted in the plug to prevent the taps from being turned past the centre, in such a way as to turn out the light, and afterwards allow of the gas escaping. These pins or stops often work loose and drop out, and when this occurs it is a very easy matter to turn the tap too far when turning off the gas, thus turning it on again; the person can merely guess as to the position of the plug by the thumb-piece, which may also, and in many cases is, twisted out of its true position, so that it is next to impossible to tell when the plug of the tap is in its proper place. Where such pins or stops are missing, it is advisable to have them renewed at once.
The plugs of gas-taps often work slack, and a slight leakage of gas occurs from them. When these slack plugs are left without attention, the nuts and washers generally fall off, leaving the plug loose. When the screw-nut hole enters the hollow of the plug, a gas-escape occurs which must receive attention, but in most cases these holes do not enter the gas-way, and as no leakage occurs if the plug is pushed in every time it is used, they are often left without attention until some person accidently leaves the plug out of its position, when it is quite possible for an explosion to result, as the leakage will soon fill the apartment.
Brackets and pendants often come loose from their fixing, and in both cases, unless the gas-fitter is called in, there will be a strong leakage. When fittings come loose-, the strain on the gas-pipes soon breaks them, and in either case the leakage is in a dangerous place - i.e. in the floor or walls.
Water-slide pendants and chandeliers are the most fruitful source of explosion. In both cases, two or three table-spoonfuls of water will be sufficient to keep them gas-tight, when they are pushed up as high as they will go, but if they are drawn down to their full extent, the loss by evaporation of the same quantity of water will soon cause a very large leakage of gas, which may fill the apartment, and, if unnoticed by a person entering with a light, may cause a disastrous explosion. When fitting new globes to chandeliers, great care should be taken to have the weights balanced to suit, as it is possible by merely changing the globes to overbalance the weights; this will not matter much so long as the tubes are full of water, hut will be dangerous where, owing to fires being kept in the room, evaporation is rapid. Another source of danger arises from the rapid deterioration of the brass chains of all chandeliers. If one of the heavy weights breaks its chain and falls, the body of the chandelier being relieved will slide down to its full extent, when there is every probability of a leakage, if it has not been attended to recently. When these weights fall they usually alarm the household, but there are many places where the fall of these weights would not be noticed, even in the daytime.
Many explosions have occurred through allowing water to accumulate in the pipes, not in sufficient quantity to interfere with the supply, but enough to make a slight rattle in the pipes, when the mice, hearing the movement of the water, may gnaw the pipe away until the gas issues.
It will be obvious then, that the whole of the gas fittings and pipes require to be periodically overhauled by a competent gas-fitter, the cost of which may be less than the price of the gas escaping from the numerous tape and joints of the fittings.
When a leakage of gas occurs, the first tiling to do is to give the apartment air by opening both windows and doors. Then go down to the gas-meter, and turn off the main-tap above the meter provided for the purpose. Next send for a gas-fitter, and if he lights a caudle to search for the escape send him away and get another. A good gas-fitter will not risk an explosion for the sake of a few minutes' time, but will cut the pipes and test them, two cuts being all that are usually required, even in a large residence, to locate the position of the leakage.