What is the maximum allowable time delay for waterflow switches?

The maximum allowable time delay for waterflow switches is typically set at 90 seconds. This time delay is crucial for allowing transient conditions that do not indicate an actual waterflow event to be filtered out. The extended period helps to prevent false alarms that may occur due to momentary fluctuations in water movement, such as in systems with varying flow rates or those that could be impacted by sloshing effects in pipes.

Waterflow switches are safety devices used primarily in fire protection systems to detect the presence of water flow, typically activated by the opening of a valve or when water begins to flow in the system. If the delay were set too short, the system could react to non-threatening conditions, compromising the reliability and effectiveness of fire alarm systems. Therefore, a 90-second delay strikes a balance between responsiveness and accuracy, ensuring that the system alerts for actual fire conditions while avoiding nuisance alarms that can lead to unnecessary fire department responses or system maintenance.

This standard is consistent across various fire safety regulations and codes to ensure uniformity in response times within fire protection systems.