Shutoff valves must be installed on the building supply and return of what type of utility system?

Shutoff valves are essential components in various utility systems, particularly because they allow for the isolation of fluid flow for maintenance, emergency situations, or system adjustments. In the case of central utility systems, which often involve heating, cooling, or distribution of water or other fluids around a building, having shutoff valves on both the supply and return lines is crucial. This configuration ensures that the entire system can be effectively controlled for operational efficiency and safety.

For central systems, it is common to encounter complex piping that may include multiple zones or extensions throughout a facility. The inclusion of shutoff valves allows for specific sections to be serviced without interrupting the entire system's operation. This is especially important in larger installations, where continuous service is necessary to maintain comfortable conditions in occupied spaces.

In contrast, while natural gas systems might require specific shutoff valves, their installation and regulation differ significantly from those of a central utility system. Chemical and solar systems have their own particular requirements and standards, but they do not typically mandate the use of shutoff valves in the same comprehensive manner as central heating or cooling systems, where these valves play a pivotal role in system management.

Thus, the requirement for shutoff valves specifically on the building supply and return in a central utility system