On the size of house drains, and the use and misuse of traps / by John Honeyman.

John Honeyman

Date:: [1887]

Credit: On the size of house drains, and the use and misuse of traps / by John Honeyman. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

3/18 page 3

$♦ 3 the importance of dealing with the aerial as well as the liquid contents of drains, we have hitherto made no adequate pro- vision for doing so. We have, no doubt, several schemes of drain ventilation which are theoretically good, and which are useful so far as they go ; but they stop a very long way short of that thorough flushing of the drains with fresh air which is desirable. In order to bring out clearly the difference between what is usually done and what I think ought to be done, let us suppose that we are dealing with a house of moderate size, having, say, two baths, three water-closets, three basins, and three sinks ; a 4 in. pipe would suffice to carry away the sewage from such a house, but in practice a 6 in. pipe would probably be used. Now in many—I fear I must still say in most—cases no attempt would be made to ventilate this drain at all, although soil-pipes connected with it would for the most part be venti- lated. In some an outlet shaft would be provided, 2 in. in diameter, in some 3 in., and in a comparatively small number shafts 4 or A\ in. in diameter. Let us consider the state of matters in such a drain with the outlet shaft of the largest size. If we suppose that the contents of the drain would fill a 4 in. pipe, the 4^ in. shaft would give an area almost equal to that of the remaining empty segment of the 6 in. pipe, so that, roughly, what we have to do is to ventilate a tube, say 5 in. in diameter and 100 ft. long, the greater part of which is horizontal. Even assuming that there are no restricting cowls or gratings at either end, it is manifest that in such a tube there could hardly be any appreciable current without the application of great mechanical force, even if we suppose the tube to be smooth and empty. But the tube we have to deal with is neither. It is rough, and it has for the greater part of its course an exposed surface, greater than that of a 5 in. tube, part of which is in motion in an opposite direction to that which the aerial current would naturally take. In such circumstances it is evident that the current would not onlv be sluo-crish but variable, now in one direction, now in another, and often, when opposing forces were well balanced, stagnant. If such be the condition of a drain with a 5 in. air outlet, I need hardly pause to consider the condition of the great majority now in use, which have nothing like so much ventilation. Of course everything depends on what we call ventilation. If we mean by that term such a change of air in the pipes as is possible under the conditions just described, we may admit that some of our house drains are ventilated; but if we mean by it constant flushing of our drains with fresh air having something like its normal proportion of oxygen, then I fear we must say that none of our house drains are ventilated—with such$

On the size of house drains, and the use and misuse of traps / by John Honeyman.

Licence and re-use

Contents