A04_2023-08-11_Tonopah_Fire_System_Check_Valves_Replacement_SOW_2.docx

Statement Of Work Two Check Valves Replacement & 5-Year Inspection Backflow Preventers – Fire Protection System Tonopah Field Office 1553 South Main Street Tonopah, Nevada 89049

Background: Backflow preventers provide a critical interface between a building's fire protection system and the water supply that feeds it. A backflow preventer is a device designed to ensure that water inside a building's fire sprinkler system flows in one direction only -- from the water main to the system's pipes. This is necessary to prevent any potential cross-contamination that can occur when water from the fire sprinkler system flows backward into the water main, carrying with it potentially hazardous contamination into the public's drinking water supply.

Backflow preventers are typically installed in wet sprinkler systems and standpipe systems in which water is held at pressure inside the pipes and only released when the system is activated. Over time, this water can become stagnant and contaminated with bacteria and chemicals such as corrosion inhibitors, antifreeze, and other chemicals added to the system.

When sprinkler systems and standpipes are connected to a public water supply, this contaminated water could potentially contaminate drinking water or "potable" water supplies without backflow preventers. Even if a sprinkler system is connected to a non-potable water source, the potential for contamination still exists if there are any cross-connections between that system and a community's drinking water supply.

Backflow preventers are equipped with two one-way valves, called check valves, which allow the water to flow only in one direction. This redundancy ensures that if one check valve fails, the other will continue to protect the water supply and create a more reliable seal, which guards against minor backflow leakages. The check valves in a backflow preventer operate independently with a differential pressure-relief valve between them, enabling the closure of one valve to reduce the pressure differential across the other. Check valves are installed in various places in a fire protection system to prevent water from backing up into the supply line.

Scope of Work: A recent test of the fire system indicated that existing check valves are not working correctly and failing the annual functionality test. The scope of work consists of replacing the existing check valves with two new 6” Ames 2000SS backflow device. The scope shall include all needed equipment, parts, labor, and retest. In addition, there is no record showing the required 5-Year internal inspection has ever been performed on the system. This test entails an internal inspection of the fire sprinkler system to ensure it is free from debris that could cause pipe or sprinkler head blockage on activation of the system. The system is drained down and dismantle a portion of the feed main and the end of the most remote branch line off the feed main and internally inspect the inside. It also entails replacing gauges older than five years and inspecting the internal workings of the riser valve (whether alarm or dry) as well the internal condition of the fire department connection (big brass device on outside of building). If everything is clear internally, the system is good for 5 more years. If debris (pictures will be taken) are discovered, then it is onto next steps. Test the debris to see what type of corrosion and then offer solutions to mitigate from there.

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