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Fire fighting system – cleaning the rust stop the corrosion.

What is a fire fighting system

Fire Hydrant in a CityA fire fighting system covers usually an entire area. Be it a factory, a shopping mall or even an entire city. There are one or more fire fighting centers where the feed water enters the system.  Often there are one or more large water tanks as buffers to ensure that there is enough water available to fight the fire right from the start. The pumps are located next to the water tanks so that sufficient water can be supplied if required. From this central location, pipes distribute the extinguishing water in branch lines to the individual areas. In an office or residential building, the pipes lead to the sprinkler system. In factories to sprinklers, on ships or offshore to fire cannons. Or simply to the hydrants on the road, as shown in the picture above. Firefighters connect their hoses to such hydrants in order to have enough water in case of fire.

The risk of fire is higher in refineries, chemical plants or offshore platforms. The same applies to efforts to ensure a perfectly functioning fire extinguishing system.

Corrosion in Fire Fighting system

In so-called wet systems, which are most of the large fire extinguishing systems, the water in the pipes is always under pressure. The reason, to have immediately enough water in case of fire. But since the water is not moving most of the time, this system tends to corrode.
During maintenance, when some valves are opened and pipes are flushed, the water often escapes dark brown. The reason for this, the loose rust from the pipe walls, is carried along with the water and this makes the water brown. This indicates that there is some corrosion in the pipes.
The higher the corrosion, the higher the risk that, in the event of fire, the dissolved rust will clog the spray nozzles of the system and not allow enough water to flow.

Trial Merus ring on a fire fighting system

hydrant fire fighting system

As a rule, a Merus ring is installed on each supply line to the fire extinguishing system. These can be large pipes of 16″ or more. We install before the shut-off valve, the tanks and the pumps. Such a pipe system is never absolutely watertight. Means that a little water is leaking out of the system all the time. To compensate for this, there are small pumps distributed throughout the system. These maintain the pressure through e.g. a 1″ line at the design pressure.

The aim of such an experiment is to remove the existing corrosion and protect the system from further corrosion by rinsing out the rust.
Immediately after installation, a sample was taken from a shut-off valve as far away from the inlet as possible. This was done at a slow speed so that the water was mainly clear.
A few days later, a second sample was taken at the same location and under the same conditions. This time the water was dark brown. A thin layer of rusty particles was visible in the sample container after a short time. The customer hardly believed how much rust was in the system and how an aluminum ring several dozen meters upstream could loosen the entire rust in this short time.
The system was cleaned by rinsing water at several points in the system until it became clean. This was done four times until no more brown water came out.

We have done this many times since. It has been shown that this test is one of the most amazing and fastest ways to show the customer how efficiently Merus technology works.

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