5.3 Control Valves, Thermal Expansion, Water Hammer & Pipe Identification

Control valves (SPS 382.40 (4))

Private water mains and water services connected to a public main

A water service connected to a private water main needs a curb stop outside the building it serves (farm buildings excepted).

Building control valve

A "water service" ends at and includes the building control valve (SPS 381.01 (282)).

Distribution system valves

Other valve rules (SPS 382.40 (8) (e)): every control valve in a water service except a corporation cock must be accessible. Stop-and-waste valves may not be buried, except for firefighting hydrants, 2-inch and larger hydrants at municipal wastewater plants, and emergency fixtures. Valves for fixtures within a dwelling unit must be accessible from inside that unit.

Water meters 1-1/2 inches or larger need bypass piping unless parallel meters are installed. Water treatment devices need a bypass, with three exceptions: one serving no more than 2 outlets doesn't need one, the bypass may be internal, and a bypass is prohibited for a device installed to remove a contaminant to meet SPS 382.70 (3).

Thermal expansion (SPS 382.40 (3) (c) 4.)

A closed water system is one with a check valve, backflow preventer or other normally closed device that keeps building pressure from dissipating back into the supply. Heating water in a closed system raises pressure quickly. The code requires the system to be protected from thermal expansion, and any water heater other than an instantaneous non-storage heater serving a closed system must have an expansion tank or other approved device with a similar function.

Worked example. A utility installs a meter with an integral check valve on a house with a 50-gallon tank heater. The system is now closed, so an expansion tank (or approved equivalent) is required on the heater. If the owner later replaced the tank heater with an instantaneous non-storage heater, the expansion tank requirement for that heater would no longer apply.

Check valves and circulation

All systems that circulate water by a pump or other mechanical means need a check valve or equal device to fix the direction of flow (SPS 382.40 (3) (f)). Hot water circulation connections must be made downstream of the control valve serving the water heater (5) (b) 6.

Water hammer arrestors (SPS 382.40 (8) (f))

Fixtures, appliances and appurtenances with 3/8-inch or larger inlets and solenoid-actuated quick-closing valves, such as clothes washers, dishwashers and ice makers with solenoids, need water hammer arrestors. Arrestors go in the fixture supplies serving those items and must be accessible.

Drilling and tapping (SPS 382.40 (8) (h))

Drilling and tapping water supply piping is prohibited, except for corporation cocks on water services and private mains and self-tapping valves serving individual appliances.

Dead ends and drainage (SPS 382.40 (8) (d))

• The system must be able to be drained completely.
• Any capped or plugged section that is dry downstream with no outlet may be no longer than 6 pipe diameters.
• When piping larger than the code minimum is used, the system must allow effective flushing at 8 ft/s.
• Hygienic sampling valves go within 6 feet upstream and downstream of a chemical injection system or a treatment device for a contaminant regulated under NR 809 or NR 140, and between tanks of a multi-tank device.

Identification of piping (SPS 382.40 (3) (d) and Table 382.40-1a)

• Label aboveground nonpotable piping and valves at intervals of no more than 25 feet, and on each side of walls, floors and roofs.
• Bands must be at least 3 inches wide with text. Tag lettering must be at least 1/2 inch high.
• Piping downstream of testable backflow assemblies must be labeled.
• A hose bibb for nonpotable water needs a label and a removable handle.
• Buildings served by both a public supply and a private well must identify each distribution system.

Each registered assembly must also carry a weather-resistant DSPS identification tag; fire sprinkler assemblies are exempt (section 6.3).