Pennsylvania Statutes Title 53 P.S. Municipal and Quasi-Municipal Corporations § 4608. Fresh air inlet

A fresh air inlet must be connected with the drain just inside of the intercepting trap.  Where underground, it must be of extra heavy cast iron.  Said inlet must lead to the outer air, and finish with an open grill, approved by the board or bureau of health, at a point just outside the front wall of building.  The fresh air inlet must be of the same size as the drain, up to four inches.

For five and six inch drains it must not be less than four inches in diameter;  for seven and eight inch drains, not less than six inches in diameter, or its equivalent;  and for larger drains, not less than eight inches in diameter, or its equivalent.