The surface of the earth is subjected to an atmospheric pressure valued about ______at sea level.

The most common serious problems being encountered in a drainage system lacking ventilation is _____________.

Trap seal loss in drainage system cause by minus pressure is ___________.

_______________is caused by a plus pressure which blows the water out of the fixture. It usually happens when a large flow of water drops and form as a slug and compresses the air inside the pipe.

This kind of trap seal loss also seldom happen and is rarely experienced by homeowners. This condition is caused by foreign objects like thread or string suspended and extended over the outlet arm of the trap.

_______________is that portion of the soil stack above the highest installed fixture branch extending through the roof. It serves as the terminal for the main vent and other vents of the plumbing installation.

____________is that portion of the vent pipe system serving as terminal for the smaller forms of individual and grouped fixture trap ventilation. It is sometimes referred to as a collecting vent line.

____________is sometimes referred to as Back Vent. It is that portion of the vent pipe system which serves a single trap. So far it is the most effective means of vent for fixture trap to prevent minus or plus pressure.

____________is employed where two or more fixture traps are installed on a horizontal soil or waste branch. The use of circuit vent generally reduces the cost of plumbing installation.