How many types of surge tank?

There are different types of surge tanks that are possible to be installed. Some of the most common types of surge tanks which are as follows:

• Simple Surge Tank: A simple surge tank is a shaft connected to pressure tunnel directly or by a short connection of cross-sectional area not less than the area of the head race tunnel.

• Restricted Orifice Surge Tank: A simple surge tank in which the inlet is throttled to improve damping of oscillations by offering greater resistance and connected to the head race tunnel with or without a connecting/communicating shaft

• Differential Surge Tank: Differential Surge tank is a throttled surge tank with an addition of a riser pipe may be inside the main shaft, connected to main shaft by orifice or ports. The riser may also be arranged on one side of throttled shaft.

  
  

In an underground development of hydropower system, tail race surge tanks are usually provided to protect tail race tunnel from water hammer effect due to fluctuation in load. These are located downstream of turbines which discharge into long tail race tunnels under pressure. The necessity of tail race surge tank may be eliminated by ensuring free-flow conditions in the tunnel but in case of long tunnels this may become uneconomical than a surge tank.