Gravity Tank Pressure Calculator

Calculate available pressure from elevated (gravity) fire protection water storage tanks based on tank elevation and piping losses

Input Parameters

Results

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Static Pressure at Sprinkler
psi
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Residual Pressure at Sprinkler
psi
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Effective Head
ft
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Tank Adequacy
Note: Gravity (elevated) tanks provide fire protection water supply by elevation head alone without pumps. NFPA 22 governs tank construction and capacity. The tank must be elevated high enough to provide adequate pressure at the highest and most remote sprinkler, including all pipe friction losses.

Reference

Gravity Tank Pressure: Effective head = tank surface elevation - sprinkler elevation P_static = 0.433 × effective head (psi) P_residual = P_static - pipe friction losses 0.433 psi per foot of water head NFPA 22: gravity tanks must provide minimum 15 psi at highest sprinkler. NFPA 13: absolute minimum operating pressure = 7 psi.