What is a "coupon" used for in water or wastewater systems?

In the context of water or wastewater systems, a "coupon" refers to a type of steel specimen that is used to assess the corrosiveness of water or wastewater. These specimens are exposed to the water in question, allowing operators to monitor the rate of corrosion and determine the overall corrosive nature of the water. By analyzing the weight loss or surface condition of the coupon after a specified period of exposure, maintenance workers can gather essential data to manage corrosion control strategies effectively. This is crucial for ensuring the longevity and integrity of pipelines and infrastructure in water and wastewater systems.

The other choices provided do not accurately represent the function of a "coupon." A device to measure pressure pertains to pressure gauges, while water sampling methods involve collecting water for analysis, and tools for providing air to tanks typically consist of aerators or air blowers, none of which relate to the concept of corrosion monitoring with a coupon.