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Flushing Your Dry Sprinkler System

Fire sprinkler systems are the most effective way to protect your property from significant property loss and interruption to business operations due to a fire. Some might argue that automatic sprinkler systems are like having a firefighter at your property 24/7. Sprinkler systems are designed to control a fire long enough to allow for manual firefighting intervention by the fire department. However, that is only if the sprinkler systems operate properly as they were designed to.


fire sprinkler installation

Over time, like all mechanical systems, sprinkler systems can begin to show signs of aging that can affect the performance of the system.  Aging dry pipe systems can be particularly susceptible to the performance degradation.  One of the biggest threats to a system not performing as designed is an obstruction, typically from scaling or MIC (Microbiologically Influenced Corrosion). Types of obstructions found in dry sprinkler systems can vary, but the potential for obstruction of the sprinkler pipe is what matters most. When the size of the foreign material is large enough to plug the sprinkler head or other area of piping, blocking water or limiting the amount of intended water that reaches the sprinkler head, it is important to remove those potential obstructions from the system.

To determine if a system requires flushing, the system should be internally inspected every 5 years to assess the internal condition of piping. If it is found that there is significant buildup of foreign objects or scaling, it is recommended to conduct a more in depth Obstruction Investigation.

If there is a significant amount of foreign material found during the obstruction investigation, there should be a flush of the sprinkler system. The sprinkler system can be considered to be relatively free of obstructions and not in need of a full flushing if:

  • Scale fragments are not big enough to obstruct a sprinkler head
  • Full, unobstructed flow is obtained from each branch line that is checked
  • Less than a half cup of scaled is flushed from the crossmains

What is a dry system flushing?

A dry system flushing involves flowing water through the dry system’s crossmains and a couple of the branchlines out the flushing connection to attempt to expel any scaling or obstructions from the piping system. The obstructions are typically trapped by burlap bags at the end discharge hose. This allows for the obstructions to be examined and help determine whether they are large enough for a full flushing to be performed on the dry system. The judgement for a full flushing is typically case to case made by the technician.

If you think that you might need to schedule a dry system flushing investigation, please contact us.

3 Reasons to Flush Your Dry Sprinkler System

1. Keep Your Dry System Free from Obstruction

Sprinkler systems are very effective when they operate as they are intended. Dry systems operate differently than wet systems, where there is a time delay from activation of the sprinklers, loss of air pressure, and the water discharging through the activated sprinklers. The successful containment of the fire depends on the water reaching the activated sprinklers unobstructed.

What happens when there is an obstruction in the sprinkler main or in the branchline where there are open sprinkler heads because they’ve activated from a fire? Depending on the severity of the obstruction, the water discharge may not reach the open sprinklers or the water pressure may not be adequate enough to control the fire, depending on the size of the obstruction. When there is a question of a possible obstruction in the sprinkler system, a system flush investigation should be scheduled with your fire sprinkler service provider.

If you think that you might need to schedule a dry system flushing investigation, please contact us here.

2. Greater Certainty of Protection During a Fire

It is one thing to install a sprinkler to protect your property and hope that it will work for you in the event of a fire, but it is another thing to have certainty that your sprinkler system will be effective in controlling a fire if and when it does happen. When you take care of your sprinkler system by implementing a preventive maintenance program that includes regular inspection, testing, and maintenance at the required intervals as recommended by NFPA 25, you will have confidence in your sprinkler system and be able to go on with your business without the fear of devastation that a fire can bring.

fire sprinkler pipe

According to FM Global and losses reported by FM Global customers in their 20-year loss data, dry-pipe systems account for approximately 59% of obstructed-pipe fires where it was found that pipe scale was found to be the most obstructing material. The reason that dry systems were most prevalent in these obstructed-pipe fires is because the pipes are not always filled with water, so when they do fill, scaling breaks off and settles to the bottom under several conditions:

  • The dry system goes through a full-trip every three years
  • The valve trips due to low air
  • Fluctuations in temperature leading to advanced condensation
  • Any other accidental trip of the dry system

By having the 5-year internal inspections completed at their required intervals and conducting a dry system flush investigation when there is evidence of foreign material, there will be a greater chance to catch an obstruction early and the sprinkler system will continue to operate effectively.

3. Minimize Property Damage & Business Interruption

Your business and the property that you manage is the most important thing to protect when it comes to operations. Fires can wreak havoc on a property without a fire sprinkler system and sometimes even properties with fire sprinkler systems (if they are neglected). Proper management of the fire sprinkler systems can make all the difference in protecting your property and minimizes property damage and business interruption.

Minimize Property Damage

When sprinkler systems are cared for properly, they will operate as they are designed to and can effectively control a fire. A big part of caring for a sprinkler system is to make sure that there are no major obstructions that could prevent water from reaching an activated sprinkler head during a fire. Having your dry system flushed at the first sign of an obstruction that could cause a blockage will help minimize the property damage if a fire does break out at your property. The damage would be limited to that of the water damage from the sprinkler activation and the original source of the fire outbreak. The cost of having your dry system flushed will far outweigh that of a major fire.

The National Fire Protection Association has a lot of great information about the impact of sprinkler systems in the United States in this article as well. It provides insight on sprinkler system performance and the causes of ineffectiveness when sprinkler systems did not operate during fires.

Minimize Business Interruption

Finally, business interruption is not typically considered when it comes to the impact of maintaining fire sprinkler systems or the lack thereof. When maintenance of fire sprinkler systems is concerned, there is minimal business interruption. The only interruption to business may be to coordinate a fire watch for the areas of your facility that are impacted by any system shutdown. Outside of pre-planned business interruption, if a fire were to occur in your facility and the sprinkler system is unable to effectively operate due to an internal obstruction, your business could suffer major interruptions to the operations which could be either temporary or permanent, depending on the severity of the fire. That being said, if your sprinkler system was able to control the fire, you would only experience the business interruption of remediating the fire and water damage that was in the affected area of the fire rather than a large portion of the facilities.

The cost of having an obstruction investigation can save you in both the short- and long-term. Don’t let cost cutting obstruct your sprinkler system’s effectiveness. Make sure you have a proper inspection, testing, and maintenance program in place for your facilities and work with a fire sprinkler service provider that you can trust. It is worth the investment in your time and resources.

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