The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California

How To Design And Install Plumbing

Traps with Internal Mechanisms. The most common form of trap depending partially on an internal mechanism to complete its seal is that provided with a hollow ball, which was supposed to drop into a concave seat after each flush of the fixture. Fig. 146. There were a number of these traps used in plumbing systems as late as twenty-five years ago. These traps were constructed of lead, and were used in connection with bathtubs and similar fixtures. Tests and experience have proved these traps inadequate.

Fig. 147 shows light metal partition traps of various designs which are now obsolete.

In concluding this chapter, it should be strongly emphasized that a trap is not a device to withstand pressure variations, and to be effective and maintain its water seal it must be ventilated adequately.

Ventilation

Ventilation of the plumbing system is that portion of the dramage installation designed to maintain atmospheric pressure within it and prevent at least three major difficulties, namely, trap seal loss, retardation of flow, and material deterioration. This phase of plumbing science is a most important one and yet, up to a few years ago, it was not seriously regarded. The average mechanic of thirty years ago was of the opinion that all that was essential to make a plumbing installation function efficiently was to install a waste pipe of sufficient size to discharge the waste materials from plumbing fixtures in a reasonable time, and to provide the waste with some sort of trap to prevent sewer air from entering the building.