Inhibitors Vs. Nitrogen

Inhibitors Versus Nitrogen, Which is the best solution for controlling corrosion in my wet fire sprinkler system...


The water treatment industry have been using corrosion control chemistries for decades to protect industrial heating and cooling (HVAC) systems from the damaging effects of corrosion. Corrosion in these systems is very diverse. There are corrosion mechanisims that influence corrosion in all industrial water systems, including wet fire sprinkler systems. In these systems, the types of corrosion is influenced by overall water quality. The most damaging corrosion being under-deposit corrosion. This type of corrosion is a by-product of bacterial contamination and overall water quality. High hardness waters will precipitate soluble minerals such as Calcium, Magnesium, Silica and Chlorides. When the temperature of water increase, (the higher elevation areas of a wharehouse), the soluble minerals become unstable and precipitate out of solution to form a deposit. When these deposits form in a pipng system, an environment now exists where bacteria flourish and the corrosion process reverts to a electrochemical corrosion process. Bacteria are well documented at initating under-deposit corrosion. The picture below gives a three dimensional view of a tubercle formation.

1) What does Nitrogen do in my wet system? Does it truly reduce the dissolved oxygen content in water? The correct answer is NO, Nitrogen will not remove the oxygen from the wet sprinkler system water. Venting the trapped air is the only way to limit trapped air in the head space of a sprinkler system. Save your money on nitrogen and consider a Huguenot Air release system.

2) Doesn't Nitrogen kill the bacteria in my wet system? The correct answer is NO, Nitrogen promotes bacterial growth, Analytical testing has verified significant Ammonia blooms of bacterial growth in system treated with Nitrogen.

3) Does Nitrogen control corrosion? Doesn't it stop all corrosion as documented by other corrosion management companies? The correct answer is NO, Other companies claim they have a electronic device that is a corrosion monitoring system, but in reality what they sell you is a device that lets you know it is time to replace your fire sprinkler system. The corrosion monitoring system supplied by others will indicate you have a severe corrosion problem only after you have experianced a 35 MILS of pipe wall thichness loss due to corrosion. This lets you know that you have lost 30% of your piping system due to corrosion. A corrosion management program supplied by Huguenot gives real time data in 90 day increments of corrosion rates per ASTM guidlines with accuracy down to 0.01 Mils Per Year (MPY).

4) Ok, if Nitrogen doesn't stop corrosion would a corrosion inhibitor do any better? The correct answer is YES, Corrosion inhibitors are well documented to control corrosion rates down to 0.02 Mils Per Year.

5) I can't see the inside of my pipes, how do you know if a corrosion inhibitor really works? Is there a way to verify the results? An ASTM certified corrosion coupon program by Huguenot Laboratories gives real time data in 90 day increments of how well the results work. The corrosion coupon pictured below shows a nitrogen treated system versus a Huguenot corrosion inhibited system. The Nitrogen treated system had a documented corrosion rate of 2.8 Mils Per Year. The Huguenot corrosion inhibited systems had a documented corrosion rate of 0.02 Mils Per Year. That indicates that a schedule 10 pipe measuring 120 Mils of wall thickness will have a service life of 6,000 years with Huguenots proven and time tested treatment programs! The Nitrogen treated system had a corrosion rate 140 times greater then the corrosion inhibited system. Be sure to ask your corrosion management company to give you physical test data that verifies the results!


6) If corrosion inhibitors work so good why is Nitrogen being promoted by other companies as the only treatment choice for my wet system? The correct answer is NFPA only recommends using corrosion and bacterial inhibitors to address corrosion issues in wet systems. Nitrogen is not recommended or referenced as a treament method for wet fire sprinkler systems.

7) Are there listing requirements to use corrosion inhibitors in fire sprinkler systems? The latest version of NFPA 25 indicates that corrosion and bacterial inhibitors shall be compatible with each other and the system components of the sprinkler system. The UL 1821-B committee is actively reviewing test methods to satisfy this requirement.

8) What do chemical manufacturing companies like Huguenot do to satisfy this requirement? Huguenot has done extensive formulary testing with many of the component manufacturing companies like Victaulic and Spears. There testing has verified 100% compatibility with those components.