Application Guide.pdf - Emerson Swan

DESIGN AND MINIMUM VALVE AUTHORITYThe available differential pressure across the hydronic circuit is transferredto the control valve once it shuts, which means that size, design and controlof the system determine the differential pressure across the control valvewhen fully shut. β design=ΔH design=Valve authority at design condition[-]Available differential pressureacross circuit at design condition[psi]β min= Minimum valve authority [-]ΔH max=Maximum differentialpressure across circuitduring operation [psi]In order to prevent the valve authority from distorting the circuit characteristictoo much, the lowest values of design and minimum authority are:To achieve this design and minimum authority, all control valvesshould have differential pressure stabilization if the pump headis bigger than four (4) times the pressure drop in the control valve(if H ≥ 4 x Δp ATC).The following pages show sevendifferent applications. Ourrecommendations to reach optimumbalancing for good control is ratedwith stars (★) based on performancevs. cost ratio.★★★ = Best Solution Best opportunities for enhancedcontrollability and energy savings★★ = Better SolutionOffers good controllability withsome first cost reduction★ = Good Solution