# Water Hammer Pressure Increase

Written by Jerry Ratzlaff on . Posted in Fluid Dynamics

## Water Hammer Pressure Increase Formula

 $$\large{ p_{inc} = \frac { 0.070 \;v \;l } { t } + p_i }$$

### Where:

 Units English Metric $$\large{ p_{inc} }$$ = pressure increase $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$ $$\large{ v }$$ = flow velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$\large{ p_i }$$ = inlet pressure $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$ $$\large{ l }$$ = upstream pipe length $$\large{ft}$$ $$\large{m}$$ $$\large{ t }$$ = valve closing time $$\large{sec}$$ $$\large{s}$$

### Solve For:

 $$\large{ v = \frac{ \left( p \;-\; p_i \right) \; t }{ 0.070 \; l } }$$ $$\large{ p_i = p - \frac{ 0.070 \; v \; l }{ t } }$$ $$\large{ l = \frac{ \left( p \;-\; p_i \right) \; t }{ 0.070 \; v } }$$ $$\large{ t = \frac{ 0.070 \; v \; l }{ p \;-\; p_i } }$$