The 7 most common sprinkler tank defects

Sprinkler tanks are at the heart of every fire protection system - but what happens when these vital systems fail? From the water exchange zone to the foil lining, various defects can impair functionality. The good news is that modern inspection technology is revolutionising the maintenance of these safety-critical systems. In this article, we will show you the typical types of damage that can occur in underground and steel tanks and how innovative Underwater drones enable efficient inspection - without the need for time-consuming tank emptying. Find out how preventive inspections can not only save you money, but also optimise the safety of your fire protection system.

Efficient inspections of sprinkler tanks in accordance with VdS CEA 4001 and FM Global Standards - underwater drones in use

When it comes to fire protection, every second counts - and every Sprinkler tank must function perfectly in an emergency. As the centrepiece of the sprinkler system, these water storage tanks have a clear mission: the immediate and reliable provision of extinguishing water in the event of a fire.

But reality shows that despite strict maintenance regulations in accordance with VdS CEA 4001, which stipulates an inspection every five years in Germany, serious defects often occur after just ten years.

The international FM Global Standards also emphasise the importance of preventive maintenance measures for the long-term safety of these critical systems. From the water exchange zone to the liner - the weak points are many and varied and can jeopardise the functionality of the entire system. But there is an innovative solution: modern underwater drones are revolutionising the inspection of these safety-critical systems. In this article, we present the seven most common defects that can occur during sprinkler tank inspections and show you how the use of underwater drones not only enables more efficient detection, but also eliminates the need for costly tank draining.

1. defects in the water exchange zone as a result of pump tests

The water change zone is the area around the water line of a sprinkler tank that is repeatedly dried and moistened during regular pump tests. This continuous change puts the coating and the material surface under stress, which over the course of years or even decades can lead to cracks or crazing. Spalling can lead to dryness. Typical causes are the constant change between wet and dry conditions, Material fatigue due to changes in humidity and microcracks caused by temperature fluctuations.

In the long term, this creeping damage can lead to Corrosion especially in free-standing steel tanks, and weaken the protective coating. Regular inspections with underwater drones make it possible to precisely monitor the condition of the water exchange zone without damaging the protective coating. Tank to have to empty it. Early intervention can prevent major damage and extend the service life of the Tanks considerably longer.

2. defects in the pipes due to abrasion of sediments

Sediments deposited at the bottom of the tank can enter the pipework during the weekly pump tests through the water flow and cause abrasion. The pump systems and supply lines are particularly affected, which can lead to increased wear and ultimately to cracks or leaks due to the recurring load.

The causes are often sediment deposits caused by corrosion or dirt particles in the water, as well as mechanical stress on the pipes due to the constant flow of water during the tests. If sediment is not removed over long periods of time, the problem is exacerbated.

The consequences: Abrasion caused by sediment can lead to considerable damage to the pipework and impair the functionality of the system.

Prevention: Underwater drones enable early detection of sediment deposits so that measures to clean the tanks can be initiated in good time before serious damage is caused by the weekly pump tests.

3. algae growth and increased corrosion due to algae metabolism

Algae growth can be a significant problem in free-standing tanks, especially when light and nutrients are present in the water. The algae's metabolism releases chemical compounds that accelerate the corrosion of the tank's metal components.

Typical causes are the incidence of light in the tank, which promotes algae growth, nutrient inputs in the water and the metabolic products of the algae, which increase the risk of corrosion.

The consequences: Corrosion caused by algae can lead to a considerable weakening of metal structures, especially on pipes and anti-vortex plates.

Prevention: Regular inspections with underwater drones make it possible to recognise algae growth at an early stage and clean the affected areas before major damage is caused by biogenic corrosion.

4. defective pipe supports due to corrosion

Pipe supports and fixings that are not made of stainless material are particularly susceptible to corrosion. Inferior materials that are not suitable for permanent contact with water often lead to serious defects.

Typical causes are the use of inferior or non-stainless materials, constant contact with water and a damp environment as well as a lack of or insufficient corrosion protection.

The consequences: Corroded pipe supports can lead to unstable pipework, which jeopardises the entire system. In some cases, pipes can even break and fall into the tank, damaging the tank itself.

Prevention: The use of underwater drones enables effective inspection of the pipe supports in order to detect and replace corroded or defective parts at an early stage before major damage occurs to the system or tank.

5. cracks in the foil lining of free-standing steel tanks

Free-standing sprinkler tanks are often fitted with a foil lining that retains the water in the tank. Cracks or damage to this foil lining can cause the tank to leak and mean that there is no longer enough water available.

Typical causes are mechanical influences during maintenance, ageing of the film, which leads to embrittlement, and tension caused by water movement in the tank.

The consequences: Cracks in the foil lining cause the tank to leak, resulting in the water availability being impaired and the tank no longer being able to fulfil its function.

Prevention: Underwater drones can inspect the foil lining throughout the tank and detect defects so that countermeasures can be taken in good time before major problems occur.

6. severe corrosion on pipes and anti-vortex plates

The pipes and anti-vortex plates inside the tank are particularly susceptible to corrosion as they are constantly in contact with water. The regular pump tests also constantly introduce oxygen into the tank, which can further accelerate corrosion. If the corrosion protection is inadequate or damaged, serious damage can quickly occur.

Typical causes are constant contact with water and oxygen, which is additionally introduced by the pump tests, damaged or worn corrosion protection and an increased chloride content or other chemical impurities in the water.

The consequences: Corrosion significantly weakens the structural integrity of the pipes and anti-vortex plates, which can impair their function in the sprinkler system.

Prevention: Regular inspections using underwater drones make it possible to monitor the corrosion status of these important components and carry out any necessary repairs or replacements in good time before major problems occur.

7. foreign bodies in the tank

Foreign bodies, such as parts from maintenance work or other impurities, can cause considerable malfunctions in the tank. They can clog pipework or block pump systems. Rusted pipe clamps, pipe parts or sheet metal parts are particularly problematic and can cause additional damage if they remain undetected.

Typical causes are carelessness during maintenance or cleaning, the entry of foreign bodies through leaking or open maintenance flaps and deposits of Rust or other materials.

The consequences: Foreign bodies can block pumps and pipes and thus significantly impair the functionality of the sprinkler system.

Prevention: The use of underwater drones makes it possible to quickly recognise and remove foreign objects before they impair the function of the system. Rusted parts can also be retrieved using grabs to prevent further damage.

Conclusion

Any extinguishing system is only as good as its extinguishing water supply - and sprinkler tanks play a central role here. Regular inspections are not only required by law, but are absolutely essential to ensure the functionality of the system in the event of an emergency. However, there is hardly any way to inspect these tanks without completely draining the water.

Here, the inspection by Underwater drone is a perfect solution: it enables a comprehensive, precise inspection of the tank condition without taking the system out of operation. Defects such as corrosion, cracks or deposits are detected at an early stage, which not only increases safety, but also ensures optimum planning for any necessary refurbishments.

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Frequently asked questions

Why do sprinkler tanks often develop defects after several years?

Sprinkler tanks are constantly exposed to water, which can lead to corrosion and deposits. These problems usually increase after around 10 years, which is why regular inspections are crucial to keep the tank in good working order.

What types of corrosion damage are frequently found in sprinkler tanks?

Common corrosion damage includes rust on pipes, pipe clamps and fittings such as anti-swirl plates. Corrosion is accelerated by constant moisture and possible algae growth in the tank, which can lead to long-term damage.

What is the water exchange zone and why is it susceptible to damage?

The water change zone is the area around the waterline where damage such as cracks and detachment of the coating can occur due to the constant change between air and water. This damage often develops over years and is difficult to recognise.

How does algae growth affect the components in the sprinkler tank?

Algae can accelerate the corrosion process, as they release acidic by-products during metabolism that attack the metal. This often leads to increased corrosion of metal components in the tank.

What role do sediments in the tank floor play in the inspection?

Sediment can build up on the tank floor and impair the function of the pumps. Sediment also favours the development of abrasion damage to the pipelines and makes it difficult to see during the inspection.

What are the typical defects caused by pipe supports and pipe clamps?

Pipe supports and pipe clamps in the tank can be damaged by corrosion and break, causing pipe parts to fall into the tank and cause additional damage. Inferior materials are often the cause.

Why are cracks in the foil lining problematic?

A tear in the foil lining means that the tank is no longer leak-proof and may no longer be able to provide the required amount of extinguishing water. The foil lining is particularly susceptible to damage due to constant moisture.

How do underwater drones help detect these common defects?

Underwater drones enable an inspection without emptying the tank and can document the smallest defects such as cracks and corrosion. The drones' 4K cameras and lighting systems provide clear images even in cloudy or confined areas.

What are the advantages of drone inspection compared to emptying the tank?

Inspection with drones saves time and costs, as the tank remains in operation and no emptying or extensive safety measures are necessary. Downtime is minimised and the inspection is faster and more cost-efficient.

How often should a sprinkler tank inspection be carried out?

Sprinkler tanks should be inspected every 5 years in accordance with VdS CEA 4001 and FM Global standards. This ensures that the function of the tank is guaranteed in the event of a fire and that expensive damage is avoided through early maintenance.