What is not included in the definition of ancillary equipment for underground storage tank systems?

The definition of ancillary equipment for underground storage tank (UST) systems typically includes equipment that supports the primary function of the UST and ensures its safe and efficient operation. In this context, fuel dispensers are not considered ancillary equipment because they are critical components that directly facilitate the delivery of fuel from the tank to the consumer. They are essential for the operation of a UST system, as they are the point at which the fuel is dispensed and involve direct interaction with the end user.

On the other hand, emergency shut-off systems, piping, and monitoring systems play important supportive roles in the overall operation and safety of UST systems. Emergency shut-off systems provide critical safety measures in case of emergencies, piping is necessary for the transport of fuel, and monitoring systems help ensure compliance with environmental regulations and facilitate leak detection.

By distinguishing fuel dispensers from ancillary equipment, it becomes clear that they serve a primary function in a UST system, making the answer to which option is not considered ancillary equipment straightforward.