Fig. 93. - Showing a Stack of Waste-Pipe, with Three Slop. Sinks upon it, as used for Testing Syphonage of Round-Pipe Traps.

5. I have made a few extracts from the "Lectures," which will be found on the following two or three pages, giving the results of some further tests with traps, and which, like the results of certain tests already given, clearly prove that a main stack of pipe, waste-pipe or soil-pipe, with branches entering it in various levels, is insufficiently ventilated, though open full bore at top and bottom, to prevent loss of seal in the traps fixed upon it.

Fig. 93 represents a stack of 2 in. waste-pipe fixed inside a house to take the discharges from three slop-sinks - one each on the 1st floor, 2nd floor, and 3rd floor; 2 in. round pipe-traps - with pieces of glass fixed in their sides, to see into them - were fixed under the sinks at a, b, and c.

(16.) Without the anti-syphoning pipe, shown in dotted lines, a pailful of water thrown down sink A syphoned more than half the water-seal out of traps b and c, and the emptying of the next pail practically unsealed them.

(26.) With the top of the main waste-pipe, e, sealed over, and a pailful of water thrown down sink b, the water-seal of traps A and c was lowered each about an inch. Another pailful robbed these traps of their seals.

(36.) With a 2 in. anti-syphoning pipe, as shown in dotted lines, the emptying of several pailfuls of water into sinks A and B produced no appreciable effect upon the other traps; but the trap under the sink into which the water was emptied lost part of its seal by momentum, or momentum and syphonage combined.

6. In fig. 94 another arrangement is shown for testing traps, and the results of some of the tests made with it follow the description of the apparatus. The main waste-pipe is 2 in., with 2 in. branches into it. A 2 in. round-pipe trap is fixed at o and P; 1 1/2 in. at Q and v; 4 in. at T; and 1 1/4 in. at u. A 2 in. anti-syphoning pipe is fixed, as shown in dotted lines, for certain experiments, and which was easily thrown out of use by shutting the stop-cocks, r, w, s. Each trap had a piece of glass fixed in one of its sides for making observations.

Fig. 94. - Showing a Stack of Waste-Pipe, with Several Traps upon it, as used for Testing Trap-Syphonage.

(lc.) Without the use of the anti-syphoning pipe, the bath was discharged by opening the quick waste-valve, but before one-fourth of the water had passed through the waste-pipe, traps p, Q, u, and v were unsealed, and trap t had lost fully one-half of its seal, but air being then admitted into the branch through the syphoned traps, the action upon this trap (t) ceased.

(2c.) The same experiment was repeated, but with the anti-syphoning pipe in proper use, and though 60 gallons of water was sent out by the bath in 2 1/4 minutes, not one of the traps lost its seal. During the greater part of the time the bath was emptying, the water stood up from an inch to two inches in the dip, or inlet, of each trap - p, t, u, v, and Q; but directly the bath was empty the water returned to its normal level. There was no oscillation of the water in any of the traps, and on measurement it was found that trap u was the only one that had lost any water, and this trap had only lost 1/8th of an inch, if quite so much.

(3c.) With a slop-sink fixed instead of the lavatory shown in the diagram, and a 2 in. trap under it, the stopcocks, R, w, s, being shut to prevent trap-ventilation, two or three pailfuls of water thrown down this sink syphoned the water-seal out of trap P, and of several others fixed on the same branch, much reduced the seal of trap o, and its own trap, Q, was left nearly unsealed by the action of momentum, or momentum and syphonage combined.

(4c.) A pailful of water thrown down slop-sink p, without trap-ventilation, syphoned the water-seal out of the several traps fixed on the same branch, also out of trap Q, and considerably reduced the depth of the seal of trap 0, and left its own trap, p, without any seal.

(5c.) With the anti-syphoning pipe in use, the stopcocks R, w, s being open, several pailfuls of water thrown down the slop-sinks, similarly to the previous tests, failed to produce any-serious effect upon the traps, except that in the trap through which the discharges were made the seal was often much reduced by momentum.

7. With the arrangement illustrated in fig. 94a, another series of testings with closet-traps was made. A stack of 3 1/2| in. soil-pipe was fixed as shown, and a Narrow-band D-trap was fixed at B, a full-sized cast-lead D-trap at c, and an " Eclipse " trap at D. A trap was fixed at the foot of the soil-pipe, at E, as was the practice with many. In some of the testings the main pipe was opened to the air, both at top and bottom, but when this is done it is so stated. A Wedgwood ware valve-closet basin, a, was fixed directly over the upper trap, as shown, and the contents of the basin discharged by means of a basin-plug placed over its outlet.

(le.) By discharging a basinful of water quickly (and sealing over the outlet of the closet-basin directly the discharge had completed its effect upon the trap under it, so that the further effect of the discharge through the main pipe might be thrown upon the other traps), the Narrow-band D-trap, at b, was syphoned, so much so that the water was left three-eighths of an inch below its dip-pipe; the cast-lead D-trap, at c, lost three-fourths of its seal by syphonage; and the "Eclipse" trap, at d, had some of its water blown out by back-pressure (to the height of three or four feet) on to the floor, causing it to lose more than one-third of its seal.