How does Nitrogen work?
Earth's atmosphere—the air we breathe—is composed of 78% nitrogen and 21% oxygen.
While oxygen is great for people, it is unfortunately very reactive with metals. When oxygen reacts with metals, such as steel pipe, the process is called oxidation. This oxidation of metal is what leads to the orange/red corrosion (rust) you see in fire sprinkler pipes.
Nitrogen, the inert gas
Nitrogen on the other hand is a stable element. It is an inert gas, which means it does not react with metals. Thus, no oxidation or rust occurs! The trick to this is removing that 21% oxygen from the fire sprinkler piping and replacing it with pure nitrogen.
Remove the ingredients of corrosion
No oxygen, no problems
Knowing that oxygen is the problem, it is necessary to remove it from the sprinkler system. Luckily, even though air contains the issue (oxygen), it also contains the answer (nitrogen). Nitrogen is the perfect substitute for oxygen. It's inert, globally available and in an inexhaustible supply.
Nitrogen Generators take the air around us and separate out the oxygen. Up to 99% pure nitrogen is then pumped into the sprinkler system to disperse the oxygenated air.
No water, no problems
While oxygen is a chief contributor to corrosion, so is the water. The nitrogen generator offers the added benefit of injecting dry nitrogen into the system. The nitrogen delivered to the system has an amazingly low dew point of -58 degree F! Talk about drying power.
Since corrosion requires all three ingredients (water, oxygen and metal), removing both the water and the oxygen has a two-fold effect!
Nitrogen Generators have 3 main components: air compressor and tank (1), nitrogen cabinet (houses the nitrogen membrane) (2), and nitrogen storage tank (3).
Steps in the nitrogen generation process:
First, air is compressed from the atmosphere and pressurized through a high pressure air compressor.
This compressed air is then fed from the air storage tank to the nitrogen cabinet.
In the nitrogen cabinet the air passes through the nitrogen membrane.
The nitrogen membrane—using an advanced hollow fiber membrane separation process—allows the nitrogen to separate from the oxygen and any other residual gas.
From the membrane, up to 99% nitrogen at a -58 degree F dew point is then piped into the storage tank.
From the storage tank, the nitrogen is piped to an Air Maintenance Device, which is connected to the fire sprinkler system.
If the fire sprinkler system supervisory pressure drops, the generator resumes operation and automatically supplies pure, dry nitrogen.
The purging process
In order to remove the initial residual oxygen and moisture in the system, you need a place to exhaust it. Potter offers two easy and efficient ways to purge these corrosive elements while still maintaining adequate system pressure—the Potter Purge Valve (NGP-SPV) and the Potter IntelliPurge Nitrogen Purge Valve (INS-PV). Each ensures that high purity nitrogen is equally distributed throughout the fire sprinkler system, giving you superior corrosion protection.
The NGP-SPV features a fast and easy installation. Simply place the unit at the end of the sprinkler system without the need for power. Once in place, follow Potter's simple nitrogen purging procedure.
The INS-PV advances on the original by integrating a precision nitrogen analyzer and a smart control board. Fully customizable, the controller allows for the purge valve to close automatically whenever your system reaches a minimum of 98%. There is no need to return and check on the system. Additionally the INS-PV consistently monitors your sprinkler system to ensure the fire sprinkler piping is protected. If any change in purity is detected, the unit can alert the contractor or facility manager.
The benefits of nitrogen
Nitrogen Generators offer benefits to any dry or pre-action system. By extending the life of the system you are gaining:
Benefits of nitrogen as a supervisory gas:
- Both an inert and dry gas
- Non-flammable and environmentally friendly
- Protects sprinkler components from oxidation
- Reduces Oxygen-Cell corrosion in steel and galvanized systems
- Reduces moisture in sprinkler systems, which helps reduce MIC