The chief objection to non-siphon traps heretofore has been that owing to their enlarged bodies they were not self-cleaning, hence they afforded a fouling place for the deposit of sediment. This objection has been overcome as a result of the discovery that water introduced with a rotary motion into the enlarged chamber thoroughly scoured it. A list of some of the non-siphon traps that have been tested and found satisfactory, together with a report of the tests and the conditions under which they were made, will be found in appendix.

Self Scouring Traps 41

Fig. 84

Self Scouring Traps 42

Fig. 35

Sizes Of Fixture Traps

Traps should correspond in size and weight with the waste pipes to which they join. Other than water-closet and slop-sink traps, fixture traps need seldom be over 1 1/2 inches in diameter, and no fixture trap need be over 3 inches in diameter.

Materials For Traps

Fixture traps are generally made of lead or brass. Lead traps should be equal to what is known in commerce as d pipe, and of the following average weight per linear foot.

Table IX - Weight Of Lead Traps

Diameter of Pipe in inches

1 1/4



2 1/2


3 1/2


Weight per Linear Foot

2 1/2







Brass traps should be of iron pipe sizes, and when connected to wrought-iron should have standard iron pipe threads. Cast brass traps should be examined to see that they possess smooth interiors, and when constructed with interior partitions they should be examined closely to see that there are no sand holes in the partition through which the water forming the seal may be lost.