The minimum static pressure at the dwelling entrance for either public or private water service (as determined by the local water authority) should be 40 psi (276 kPa). The maximum static pressure should be 80 psi (552 kPa). When the pressure from the public water main or private well exceeds 80 psi, a pressure-reducing valve or regulator should be installed at the point where the water service pipe enters the dwelling. The pressure regulator should be installed immediately downstream of the main shut-off valve. To allow a continuous flow of water to the dwelling, the water pressure-reducing valve is designed to remain in an open position if the component fails.
All water pressure-reducing valves should be designed to allow repair and removal of parts without requiring the removal of the valve from the water supply pipe, or breaking the pipeline. The strainer for the valve must also be available for inspection and periodic maintenance without removing the valve or breaking the pipeline. www.nachi.org