fire sprinkler

Nitrogen: Membrane vs PSA Technology

It has been established that replacing the Oxygen in your sprinkler pipes with Nitrogen will reduce, or even stop, corrosion; thus, significantly extending the service life of your sprinkler pipes, and reducing maintenance and repair costs.

Since the solution to corrosion is nitrogen, the question becomes how to produce and inject Nitrogen into your fire sprinkler system. There are two methods for Nitrogen generation, Membrane technology and PSA technology.

Membrane Technology
Nitrogen generating membranes line the fire sprinkler pipes and generates gaseous Nitrogen on-site. The polymeric hollow fiber, which makes up the membrane, permeates oxygen, water vapor, and impurities out of sidewalls, allowing Nitrogen to flow through its center. Membranes require a minimum of 125 PSI of clean, dry compressed air. A refrigerated air dryer will ensure clean and dry air is reaching the membranes. This is important for increasing the lifespan of the membrane, as properly designed and maintained membranes can have a lifespan of 8 to 13 years.

PSA Technology
Pressure Swing Absorption (PSA) technology has vessels full of Carbon Molecular Sieve (CMS). Under high pressure, CMS absorbs impurities, allowing Nitrogen to pass through and into the Nitrogen receiver tank. This is an efficient way to generate nitrogen as it has an air to nitrogen ratio of 2:1, while the ratio for membranes is 3:1. It has a greater longevity and performance as the lifecycle before re-nourishment is 20-25 years. It holds 98%+ purity for longer and outputs 39% more nitrogen production. PSA technology also requires 46% less air compressor load, which will significantly increase the life of your air compressor.

Complimentary Technology for Corrosion Protection
High purity Nitrogen must be equally distributed throughout the entire sprinkler piping system in order to effectively inhibit corrosion. An automatic, pneumatic vent should be installed at each riser of your fire sprinkler system to provide a low volume, constant purge of Nitrogen throughout each fire protection system. This vent also provides a testing point for monitoring Nitrogen levels in the system.

A portable, nitrogen purity sensor is a hand-held device that can be connected to your pneumatic vent or at any system sampling port to verify the desired levels of Nitrogen are being achieved throughout the sprinkler system piping.

For large systems, or systems that are monitored offsite, you have the option of utilizing an electronic manifold that can monitor each Zone of your system and track a daily sampling of Nitrogen levels. If purity does not meet specifications during a sampling phase, the manifold will cause the Nitrogen vents to remain open for a continual purge until the next sampling phase. You Nitrogen generator will provide the Zone with more Nitrogen until purity specifications are met.

You can learn about corrosion solutions for Wet and Dry/Pre-Action systems, or the length of service life for specific steel types at A1’s Blog.

A1 is a leading expert on the latest technology in life safety. To find out more information or to ask a question, click here or call us at 1-800-859-6198.

Greg Lane

Stop Dry Sprinkler Pipe Corrosion

Understanding the correct cause can help you to slow or stop dry sprinkler pipe corrosion.

Microbiologically influenced corrosion (MIC) was once thought to be the primary threat to sprinkler pipe longevity. However, further research has found that oxygen is the primary factory in sprinkler pipe corrosion for both wet and dry pipe systems. In this article, we will discuss how corrosion occurs in a dry sprinkler system and the options for preventing or slowing this corrosion in order to maintain your system and extend the life of your sprinkler piping.

The corrosion triangle illustrates the three factors necessary for corrosion to take place: an unprotected metal, electrochemical potential in the form of oxygen, and electrolyte in the form of moisture. When all three factors are present, there interaction results in corrosion of the unprotected metal. To prevent corrosion, you must remove one factor in the corrosion triangle.

Removing the Unprotected Metal from the Equation

Galvanized steel prevents corrosion by having a protective surface between the metal and the water or air; Black steel pipe has little to no protective coating. However, both galvanized steel and black steel pipes present opportunities for corrosion – an issue we will go into further in a future blog.

Removing Water from the Equation

The definition of a dry sprinkler pipe system says that the sprinkler pipes are dry – without water. And this is true, the purpose of a dry sprinkler system is to provide piping without water in sensitive areas, such as areas where the water in sprinkler pipes would freeze or locations where any water leakage could cause serious damage. (Although, if your sprinkler system is located in an area where any water can cause serious damage to the facility or equipment, it is best to look at other fire suppression options such as aerosol based or clean agents.)

However, dry sprinkler pipes will still collect trace amounts of water due to hydrotesting, flow testing, and condensation. Even when you properly drain the system on a regular basis (read more on how to drain your dry system pipes here – drip drum blog), the water is present and can react with the pipe and oxygen to create corrosion. The remaining option is to remove the oxygen from the dry pipe system in order to prevent corrosion.

Removing Oxygen from the Equation

Dry sprinkler and pre-action system pipes are pressurized with air until the system is alerted that a fire is occurring, at which time the sprinklers activate releasing the air from the system and filling the pipes with water. Instead of pressurizing these pipes with air, however, you can pressurize them with nitrogen, which does not react with the water or pipes to create corrosion.

Ongoing, long-term exposure tests have been conducted, and have shown that nitrogen filled sprinkler pipes slow or stop corrosion and extend the life of the sprinkler pipes significantly. This preventative measure for your dry sprinkler system can save you money in costly repairs due to corrosion including property and equipment damage, ongoing repairs to pipes or full system replacement, sprinkler head blockages, and an inoperable fire protection system that puts your people and assets at risk.

Nitrogen arrests electrochemical, galvanic and MIC corrosion. The nitrogen also prevents ice plugs by ensuring a -40F to -70F dew point within the sprinkler system. As high purity nitrogen enters the sprinkler piping, corrosive oxygen is displaced – preventing corrosion, slowing corrosion that may already have occurred, and maintaining your sprinkler system for a longer life span.

A1 is a leading expert on the latest technology in life safety. To find out more information or to ask a question, click here or call us at 1-800-859-6198.

Greg Lane

Fire Sprinkler Inspections

Fire Sprinkler inspections are an important step in your Life Safety program.

Sprinklers are very reliable and can last as long as the building in which they are installed. As with any other mechanical system, sprinkler systems and its external components each have their own design, inspection, and maintenance requirements. As you would expect, there is a long list of inspections and tests required. Weekly, monthly, quarterly, and annual tests of items such as bearings, couplings, coolant, fuel, batteries, oil, gauges, etc. are just a small sampling. In addition, the different systems must be run tested periodically to ensure functionality.

Sprinkler inspections differ somewhat based on what type of system you have, but all systems must have professional inspections quarterly, semi-annually, and annually. Fire sprinkler systems are comprised of piping, sensory parts, sprinkler heads, pumps, valves, gauges, and many other parts that work together in order to provide fire protection. If any one of these parts has a problem, it can cause your system to work less efficiently or become inoperable. Regular maintenance and inspections of the equipment will not only ensure everything is working and ready if needed it will also help eliminate costly repair bills down the road due to neglected equipment.

For a complete list of what inspections are required for each system, visit A1’s inspections page, or check out our comprehensive Inspections Ebook.

In between your professional inspections and maintenance, it is important that you check your fire safety systems and devices. Look for leaks, damaged areas, gauges that are not in the proper range, rust, or any other indicators that your system may not be functioning properly. Self-inspections will allow you to catch problems early, alert your fire safety company, and keep your system running to protect lives and assets. As always, some cities and states require more frequent professional inspections so be sure to check your State and Local Code.

A1 is a leading expert on the latest technology in life safety. To find out more information or to ask a question, click here or call us at 1-800-859-6198.

Nick Duke
Nick Duke
A1 Inspections Supervisor