Short Answer:

A surge tank is a vertical storage chamber connected to a pipeline, and its main role is to control water hammer in hydraulic systems. When sudden changes in water flow or pressure occur—like during pump stoppage or valve closure—the surge tank absorbs the pressure surge and prevents damage to the pipes and equipment.

By temporarily storing or supplying water, the surge tank helps to balance the pressure and reduce shock waves in the pipeline. This makes the system more stable and protects it from the harmful effects of water hammer, such as vibrations, noise, and pipe rupture.

Detailed Explanation:

Role of surge tanks in controlling water hammer

In civil and hydraulic engineering, water hammer is a sudden rise in pressure caused by the abrupt stoppage or change in water flow within pipelines. If not controlled, it can lead to damage like pipe bursts, valve failures, or structural damage. To manage this issue, surge tanks are used as protective devices, especially in long pipelines, pumping systems, and hydropower stations.

A surge tank is an open or closed vertical tank connected to a pipeline near the pump or high-pressure zone. It acts as a shock absorber that helps manage and reduce water hammer effects.

How Surge Tanks Work

1. Absorbing Pressure Surges
   When a valve is closed or a pump stops suddenly, the flow of water in the pipeline cannot stop immediately due to its momentum. This causes a pressure wave (water hammer) to travel backward. The surge tank absorbs this extra water, reducing the intensity of the pressure wave.
2. Providing Water During Pressure Drop
   If there is a sudden demand or drop in pressure, the surge tank releases stored water into the pipeline. This helps maintain a smooth flow and avoids vacuum formation or reverse flow, which can also cause water hammer.
3. Balancing Flow Fluctuations
   During normal operation, the tank acts as a buffer between the pump and the pipeline. It takes in excess water when pressure is high and supplies it back when pressure is low. This helps maintain steady pressure and flow.
4. Reducing Shock Waves
   By giving the water a place to go when its path is suddenly blocked, the surge tank prevents the build-up of high-pressure shock waves that would otherwise damage the system.

Types of Surge Tanks

• Simple Surge Tank: An open tank that allows water to rise and fall freely.
• Restricted Orifice Surge Tank: Has a small opening at the bottom, which slows the inflow and outflow to control pressure changes more smoothly.
• Differential Surge Tank: Has an inner chamber that helps fine-tune the response to flow changes.

Each type is selected based on system design, length of pipeline, and operating pressure conditions.

Advantages of Using Surge Tanks

• Protects pipes, pumps, and valves from high-pressure damage
• Increases the life of hydraulic systems
• Reduces maintenance and repair costs
• Improves safety and reliability of water transport systems
• Supports smooth and continuous operation

Conclusion:

Surge tanks play a vital role in controlling water hammer by absorbing excess pressure and providing water during flow fluctuations. They act as a buffer to reduce shock waves and protect hydraulic systems from damage. Using surge tanks ensures safer, smoother, and longer-lasting operation of pipelines and pumping systems in civil engineering projects.