To prevent water hammer, pumps are started at what condition?

To prevent water hammer, pumps are started at what condition?

• A. Deadhead
• B. Low Flow
• C. Full Discharge
• D. Maximum Speed

Answer: (A)

Starting a pump into a deadhead condition, where there is essentially zero flow in the line, minimizes the risk of a hydraulic transient. With no moving water to accelerate, there isn’t a momentum to unleash into the piping as the pump ramps up. As the pump starts, pressure and flow can be built up gradually, and the discharge path can be opened or the speed can be increased slowly to avoid a sudden surge. If you begin with some flow or with the discharge fully open, or run the pump at maximum speed from the outset, a rapid acceleration of a moving water column can generate a strong pressure spike — a water-hammer scenario. So starting with zero flow provides the gentlest initial condition, reducing the chance of a damaging pressure transient.

Starting a pump into a deadhead condition, where there is essentially zero flow in the line, minimizes the risk of a hydraulic transient. With no moving water to accelerate, there isn’t a momentum to unleash into the piping as the pump ramps up. As the pump starts, pressure and flow can be built up gradually, and the discharge path can be opened or the speed can be increased slowly to avoid a sudden surge. If you begin with some flow or with the discharge fully open, or run the pump at maximum speed from the outset, a rapid acceleration of a moving water column can generate a strong pressure spike — a water-hammer scenario. So starting with zero flow provides the gentlest initial condition, reducing the chance of a damaging pressure transient.