What is an acceptable alternative to using a valve and nipple configuration for auxiliary drainage on dry systems?

Using a listed device as an alternative to a valve and nipple configuration for auxiliary drainage on dry systems is appropriate because listed devices are specifically designed and tested for use in fire protection systems. These devices meet specific standards established by safety organizations and provide the reliability and performance needed in fire suppression systems.

In dry sprinkler systems, it's crucial to ensure that water is adequately drained to prevent freezing and potential system failure. A listed device fulfills this need by providing a reliable method for auxiliary drainage that complies with the relevant codes. This ensures that not only does the system operate efficiently, but also that it adheres to safety regulations.

While other options might seem feasible, they don't fulfill the specific requirements outlined for fire suppression systems. A pump system, for example, might not provide the same level of straightforward drainage functionality, while a drain trap could be cumbersome and not designed for the same purpose. An inline filter doesn't serve as a drainage solution at all but rather helps ensure clean water circulation within the system. Thus, opting for a listed device aligns with the requirements for functionality, safety, and code compliance in dry sprinkler systems.