What is surge tank? Explain with types.

Surge tank and its types

Definition-

Surge tank is defined as ' the tank used to control the sudden pressure change in the pipe line due to                  

a)     Sudden opening and closing of valves'.

b)    At the time of start or stop of turbine.

There are three main types of surge tanks-   

1)    Simple or open type surge tank 

2)     Restricted orifice type surge tank 

3)    Differential surge tank

1) Simple or open type surge tank -

Fig. Cylindrical and conical open type surge tank

fig. cylindrical open type surge tank

   1)    These are directly connected to pipeline.

   2)    They are in cylindrical or in conical shape.

   3)    The top of the simple surge tank is open to the atmosphere.

   4)    Accelerating and retarding heads are small therefore water flow in and out from surge tank is slowly.

          

2) Restricted orifice type surge tank- 

fig. Restricted orifice surge tank

   1)    These are directly connected to pipeline.

   2)    They are in cylindrical shape.

   3)    They have restricted opening at the bottom so it also called as throttled surge tank.

   4)    The water flow through restricted opening causes high friction so it produce very high acceleration and retarding heads ,results it take very less time for surging action.

3) Differential surge tank-

Fig. Differential surge tank

   1)    It has combined advantage of open and restricted type surge tank.

   2)    Also it has additional feature of riser. When the load on turbine decreases water flow in the riser.

   3)    Similarly when load increases water flows out from the riser into turbine. Differential surge tank is better than the simple type and restricted type surge tank.