How do you calculate total dynamic head (TDH) for a sprinkler zone?

• A. TDH equals static pressure at the source plus elevation head plus all friction losses along the supply line and fittings
• B. TDH equals static pressure
• C. TDH equals elevation head only
• D. TDH equals friction losses only

Answer: (A)

Total dynamic head is the total energy the pump must overcome to deliver water to the sprinkler zone. It combines three things: the pressure energy at the source (static pressure), the gravitational energy from the vertical rise to the zone (elevation head), and the energy lost due to friction and fittings along the supply line (friction losses). So you add static pressure, elevation head, and all friction losses to get TDH. Just using static pressure misses the lift and losses, elevation head alone misses pressure and losses, and friction losses alone miss the initial pressure and lift.