What is a Surge Tank?

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  • Written By: Mary McMahon
  • Edited By: Kristen Osborne
  • Last Modified Date: 20 January 2020
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A surge tank is an attachment to a pressurized system designed to accommodate pressure changes. Its purpose is to neutralize rises and falls in pressure to prevent system failures, blowouts, and other problems. These devices can be used with a number of different types of systems ranging from the fuel lines in vehicles to the systems used to regulate water levels in swimming pools.

The surge tank is attached at the highest point of the system. When pressure rises, forcing fluids upward, they shift into the tank rather than blowing out the system. In the swimming pool example, if several people jump into a swimming pool at once, the water flows into gutters and rises into the tank instead of slopping out of the pool. The ability to accommodate a sudden increase in pressure is critical with closed systems like radiators, where the increased pressure cannot be vented and could cause a rupture.

If the pressure drops suddenly, the surge tank can fill in with a reserve of fluid until the pressure is equalized again. Tanks attached to fuel lines in vehicles, for example, will step in and deliver fuel to the engine if there is an interruption in the fuel line. While the tank cannot keep the system going forever, it can stabilize it long enough to fix a problem or bring the system to a safe stop for inspection and repair.


Surge tank design is dependent on the system is attached to. The device usually has a set of valves to control movements of fluids and gases from the tank, and it may have an emergency relief valve designed to release pressure in the event of an emergency. These tanks can also be used to bleed air out of a system, as air will rise to the top, and it can be vented while a valve keeps fluids safely inside the system.

When installing a surge tank, it is important to use one designed and rated for the system. If the tank is not fitted properly or it is not strong enough, a catastrophic failure can occur. Many companies make tanks designed for various applications, and it is possible to order custom models for particular settings, in the event that there is a special need. People fitting them to vehicles that do not come with a stock tank should be aware that such modifications can void a warranty.


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Post 3

My brother made a DIY surge tank for this car he converted to fuel injection for racing. He had to because the car kept cutting off when he took sharp turns.

Post 2

@Vegemite – It would be a lot less fun at the pool if it overflowed like that, so those tanks are important! My dad works for the city, and he was telling me that a bladder surge tank is also really important because it helps keep your city’s water pressure constant, in the case of a blockage or pump malfunction.

They’re used in factories too, and any other place where lots of water is moved through pipes.

Post 1

I had no idea that every swimming pool has a water surge tank. Now that I think about it, it makes perfect sense. It wouldn’t be good if a pool overflowed every time a lot of people jumped in. Eventually, the water would go down and it wouldn’t be any fun to swim in! Not to mention the watery mess that would be all around the pool.

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