§ 330-56. Riser lines.

A. 

The diameter of all riser lines in plumbing systems shall not be less than 3/4 inch; except that when lead, copper or brass pipe is used, the minimum diameter may be 1/2 inch. Separate stopcocks or valves, so located as to be accessible at all times, shall be placed at the foot of each riser line and, in all buildings other than residence buildings occupied exclusively by one or two families, on each branch line from the riser for each isolated fixture or each group of fixtures, such as bathroom fixtures, kitchen fixtures, etc., except that only one stopcock or valve shall be required for the fixtures contained in any one apartment, suite, store or loft occupied by one tenant, when all the fixtures contained in each apartment, suite, store or loft are supplied from one branch line.

B. 

Diameters of branches to any fixture must not be less than 1/2 inch, except when used to supply water closets, cisterns or lavatories. Branches for flush valves for water closets must not be less than 1 1/4 inch in diameter and for urinals not less than 3/4 inch in diameter.

C. 

Where a hot water supply system is installed, the distance between the hot and cold water risers should not be less than six inches. Where it is impossible to place them six inches or more apart, the hot water riser must be covered with an approved insulating material.

D. 

All risers and branches must be properly fastened.

E. 

Relief valves must be provided where necessary.

F. 

Water siphons are not allowed.

G. 

All sterilizers must have check valves; and where flushometers are used, vacuum breakers must be provided.

H. 

Pressure regulators must be installed in order to protect the water system in all buildings from excessive water pressure.