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Generally Speaking

News and Information about General Air Products Fire Protection and Industrial Equipment

  • How To Select Air Compressors for Fire Sprinkler Systems

    Fire Protection Air Compressors for Dry Systems

    Fire protection air compressors are not often looked at closely by designers and installers, but when the wrong type of compressor is used the facility manager gets very familiar with them. A little work and a little education on the front end of an installation will ensure a long and problem-free life for the compressor. That is what this article is designed to provide.

    Below is a list of questions that will serve as a guide to help you choose the correct type of air compressor for your fire sprinkler installation. Hint: “Stop by Home Depot and grab the cheapest one” is not the answer to any of the questions.
    • What is the size of the largest system size in gallons? Sizing by horsepower wastes money!
    • How many systems will the air compressor be serving? Three systems per compressor is ideal.
    • Should you use a riser mount or a tank mounted air compressor?
    • Does the facility have a solid maintenance schedule in place for the air compressor?
    • In what type of environment will the air compressor be installed?
    • Who is taking ownership of the electrical responsibilities of the air compressor at installation?

    If you can answer all or most of these questions before the installation takes place, you can be sure to have provided a long-lasting, trouble-free air supply solution for your project.

    What is the largest system size in gallons?

    The primary driver of air compressor selection is the NFPA 13, Standard for the Installation of Sprinkler Systems, code requirement for a “30-minute fill.” Most information on fire protection air compressors in the market will provide a capacity rating in gallons (i.e., OL12516AC is a common model that is rated to fill a 125-gallon system or less to 40 psi in 30 minutes or less). The capacity rating in gallons is calculated using an equation that takes into account flow and pressure over time. It is the flow part that is key here.

    Fire protection air compressor manufacturers are concerned with high flow, not horsepower. Conversely, a retail type of air compressor—the type you would find at a home improvement store—is concerned more with pressure and horsepower, not flow. This is because these compressors are built to different quality standards and for different purposes.

    A fire protection air compressor is designed to last for the life of the system and will typically have a run life of 5,000 to 8,000 hours. Retail-quality compressors have a run life between 500 to 1,000 hours. Also, a fire protection air compressor will typically have a very high flow when compared to the retail type. The reason for this is that a fire protection air compressor is designed to fill the sprinkler system to pressure in 30 minutes with the smallest possible horsepower. Next time you are at Home Depot, look at the flow for one of the compressors they sell, then pull up a cut sheet for your favorite fire protection air compressor and look at the cubic foot per minute (CFM) compared to the horsepower – you will see a sizeable difference.

    So, why does knowing your largest system size in gallons save you money? Because there is a big difference in price between a one-horsepower retail type air compressor and a one-horsepower fire protection air compressor. When you make sure that you have sized your fire protection air compressor by flow and system size, the price difference is often small – and as an added bonus you will get a piece of equipment that will last the life of the system as opposed to one that will struggle to last the life of the install warranty.

    How many systems will the fire protection air compressor be serving?

    How many sprinkler systems should I have on one air compressor?

    There is no restriction in NFPA 13 on the number of systems that one fire protection air compressor can serve. If you want to put one air compressor on 20 dry systems, no one can stop you. Someone should, but technically they can’t. The reason to consider the answer to this question is to ensure long-term performance and reduce regular maintenance.

    The more systems that are attached to one air compressor, the more it will need to run to keep up with the leak rate of each system. If you were to put one compressor on 20 systems, be aware that your air compressor will be running constantly to keep up with demand – expect it to become problematic fairly rapidly. Also be aware that this issue is magnified significantly with the use of a nitrogen generator – important to know but a separate topic.

    FM Global offered a recommendation for one air supply unit per three systems when it came to freezer rooms. This is a good guideline to carry over into all dry and pre-action sprinkler systems as it will protect the life expectancy of the air compressor. Furthermore, the more a compressor runs, the more maintenance will be required. By putting no more than one air compressor per three systems you will keep the run time of the air compressor to a manageable amount as the system ages.

    When should you use a riser mounting versus a tank mounted fire protection air compressor?

    If you are connecting one air supply to multiple risers it will require the use of a tank mounted air compressor and code states that each system attached to the air compressor requires its own air maintenance device. Really, a tank mounted air compressor is the best option when it comes to air supply no matter the number of systems.

    When should you use a riser mounting versus a tank mounted fire protection air compressor?

    If you are connecting one air supply to multiple risers it will require the use of a tank mounted air compressor and code states that each system attached to the air compressor requires its own air maintenance device. Really, a tank mounted air compressor is the best option when it comes to air supply no matter the number of systems.

    When you use a tank mounted type air compressor it allows you to introduce extra volume to your systems. Consider this set up – three risers, two require 20 psi and one requires 40 psi. The use of a tank mounted air compressor allows first for the use of one air compressor, where as the use of riser mounting compressors would require three. Furthermore, you have the ability to set the tank mounted air compressor for its highest setting – 60 to 100 psi is common. Then, use the air-maintenance devices to regulate down to the pressure required for each system. The increased stored pressure means that the air compressor will run less frequently and this will help the unit to last for a long time before replacement is required.

    Riser mounting air compressors are best for riser rooms where there is no space for a tank mounted unit. Typically, they perform very well on new, small systems. Also, note that riser mounting air compressors do not have to be mounted on the riser. Check with the manufacturer’s instructions for proper orientation but understand that in situations where the riser is not ideal for mounting contractors should consider mounting the compressor on the wall or the floor.

    Does the facility have a solid maintenance plan in place for the air compressor?

    A solid maintenance plan is the key to a successful operation of all durable goods – a fire protection air compressor is no different. Answering this question before choosing an air compressor for a new installation will tell you if you should be purchasing a lubricated or an oil-less type unit.

    Oil-less and lubricated are the terms used for the two primary types of compressors seen in the fire sprinkler industry. Lubricated type air compressors are less expensive than oil-less types on the initial purchase. Under usual circumstances, if maintenance is not performed on a lubricated air compressor it will break quickly. One of the most common failures of these units is simply neglecting oil changes. If the oil is not looked at regularly and changed appropriately, the pump will seize and the unit will fail.

    If your customer has a good track record for maintenance, a lubricated type of air compressor can be a good choice. If the maintenance record for the facility or building owner is in question, an oil-less type compressor is the best choice. While oil-less units are not “set it and forget it” by any means, they are designed to run optimally with far less maintenance.

    Be sure to ask yourself this question before you select a compressor type: a neglected lubricated air compressor that runs regularly will require an oil check inside of the first year!

    In what type of environment will the air compressor be installed?

    This question goes hand-in-hand with the question of maintenance. Is the environment dirty or clean? If it is dirty, an intensive maintenance regiment is recommended. Clogged intake filters are another common failure point on air compressors – this affects both oil-less and lubricated type air compressors equally. Also consider the environment from the standpoint of what the compressor is intaking – is it in a janitor’s closet with chemicals? How will those chemicals affect the compressor? Ammonia and air compressors are not friends. Is it near a body of salt water? That is as corrosive to the inside of the air compressor as it is to the outside of the sprinkler piping. Is the compressor installation heated area? An air compressor needs to be installed in a part of the building that never goes below freezing.

    If the compressor installation area is clean, you should also look into the intended use of the area. If it is going to be in or around an area where people will be living and working, a quiet fire protection air compressor should be used.

    Who is taking ownership of the electrical responsibilities of the air compressor at installation?

    Electrical Wiring Guide for an OL12516AC Air Compressor. Electrical Wiring Guide for an OL12516AC Air Compressor.

    When we talk about fire protection air compressor issues we can not leave out electrical issues. The air compressor is the crossroads for the mechanical and electrical disciplines on a dry pipe or pre-action sprinkler system. The competence of the electrician is as critical to a fire protection air compressor installation as the competence of the sprinkler tech. At initial installation, if the electrician improperly wires the air compressor, nine times out of 10 the fire sprinkler contractor will be paying for it. Often, an electrical problem with the compressor will not produce a failure of the unit until weeks or months later.

    It’s not fair; it’s just real life. Without delving too deep into that unfortunate reality, a good practice to avoid electrical problems all together is to find out who is doing the electrical installation and touch base with them. Make sure they have someone with experience wiring industrial equipment. Be there when they are wiring the compressor and make sure to have the phone number for the manufacturer of the air compressor on stand-by so that you can consult them should any problem arise.

    So, for a piece of equipment that usually appears in design drawings as a square with “COMPRESSOR” written inside, this is a long article. Believe it or not, this is a summary. There is a lot to cover on the proper selection and use of fire protection air compressors. We are all working to be better at what we do, so the number one thing to take away here is that training is vital – there is a lot to know about the less glamorous components of a fire sprinkler system. Learn more. Train more. Work smarter.

  • General Air Products Named a NICET Recognized Training Provider

    As a prominent certification provider for many Fire Protection Engineers, the National Institute for Certification in Engineering Technologies (NICET) sets a rigorous standard for the knowledge of industry professionals. General Air Products is proud to announce that they have been named a Recognized Training Provider for Fire Sprinkler Training by NICET.

    Get NICET Training for Fire Sprinkler Systems

    Continuing Professional Development training is a requirement for Fire Protection Engineers to maintain their NICET certifications. General Air Products works with engineers, designers and field technicians to provide NICET credited training. Scheduled Training Events are listed on our website and customized courses are available upon request.

    The Fire Sprinkler Training Center by General Air Products

    Hands-on Dry Pipe Valve Fire Sprinkler Training

    Featuring a state-of-the-art 40-seat classroom and a live equipment lab with ten sprinkler risers, The Fire Sprinkler Training Center at General Air Products, located just outside of Philadelphia in Exton, PA offers Fire Protection professionals an opportunity to receive training from a variety of suppliers and manufacturers in a hands-on learning environment.

    Fire Sprinkler Industry Professional Receive NICET Training from General Air Products

    To receive training toward NICET CPD points, NICET certified professionals may attend classes or request customized fire sprinkler training on a variety of topics, including:

    • Commercial Fire Pump Troubleshooting
    • Backflow Prevention
    • Nitrogen Generators in Fire Sprinkler Systems
    • Methods of Corrosion Control in Fire Sprinkler Systems
    • Cold Storage / Freezer Room Sprinkler Systems
    • Residential (NFPA 13D) Sprinkler Systems
    • CPVC - Proper Use & Installation
    • Air Vents, Auxiliary Drains, and Inspector Test Valves
    • NFPA Code Compliance & Changes

    Backflow Preventer Training for Fire Sprinkler Systems

    General Air Products’ many partnerships across the Fire Protection industry allow for a diverse range of courses tailored for Fire Protection Engineers and Sprinkler Installation Technicians alike. While receiving training in the classroom and getting hands-on in the live equipment lab, professionals who attend will receive the benefit of engaging with an array of product experts from every part of the sprinkler industry.

    The General Air Products Training Center features live fire sprinkler training equipment from nearly every major manufacturer in the industry.

    We'd like to extend our thanks these Partners, who have given time, equipment and continued support to The Fire Sprinkler Training Center at General Air Products, and who share in the value of training as a cornerstone of the Fire Protection industry: AGF Manufacturing, AMES Fire & Waterworks, Anvil International, Backflow Direct, Blazemaster, Core & Main Fire Protection, Ferguson Fire & Fabrication, Globe Fire Sprinkler, GVI, Johnson Controls, Potter Electric, Reliable Automatic Sprinkler, SPP Pumps, Tornatech, Victaulic, Viking SupplyNet, Wheatland Tube, & Zurn.

    To register for one of our scheduled Training Events or request custom Fire Sprinkler Training for your team, please visit training.generalairproducts.com or call 1-800-345-8207.

  • What do Beef Jerky and Corrosion Mitigation for Dry Pipe and Pre-Action Sprinkler Systems Have In Common?

    Dry Air for Corrosion Mitigation – it’s being used all around you!

    Dry air is a proven technology for corrosion mitigation in many industries, including fire sprinklers. You might be surprised to learn that your bag of beef jerky is utilizing the same principle that we apply to your sprinkler system with our dry air generators.

    The picture below shows the small bags of desiccant that you find in all sorts of products you buy, sneakers, medicine, and many types of food. They often say “Desiccant: Do not Eat” - for real, don’t eat it. These packets of desiccant are designed to soak up the moisture in the package so that the air inside remains dry, protecting the product from growing mold, from discoloration or from corrosion.

    Dry Air by means of desiccant is used in a variety of industries, including fire sprinklers, to inhibit corrosion and mold.

    A dry air generator, like our Dry Air Pac®, contains several pounds of desiccant (don’t eat ours either) that the air from our compressor travels through before it goes into the system. When the compressed air meant for pressurizing your dry pipe sprinkler system travels through the desiccant beds nearly every bit of moisture is removed. The air, upon exiting the compressor / dryer unit, is then dry to anywhere between -40F and -70F PDP (pressure dew point). Note that PDP is a moisture measurement not a temperature rating.

    The effect this has on the moisture inside your dry or pre-action sprinkler system is twofold. First, as the air being used to pressurize the system is dry that means that there is not a steady contribution of moist air as there is when a standard air compressor is being used.

    Second, the air pressurizing the system is so dry that as it sits in and ultimately leaks out of your system it causes any residual moisture inside your sprinkler piping to be removed. Any environment kept at a low dew point or low relative humidity will interrupt the corrosion process. Put another way, the dry air inside the pipe evaporates the moisture sitting on the inside walls of the pipe or in shallow pools along the length of the pipe.

    The Corrosion Triangle: For corrosion in fire sprinkler systems to occur three things must be present: a metal, water and oxygen. Dry air generators remove the water and nitrogen generators remove the oxygen. The Corrosion Triangle: For corrosion to occur three things must be present: a metal, water and oxygen. Dry air generators remove the water and nitrogen generators remove the oxygen.

    While nitrogen eliminates the air part of the corrosion triangle, dry air reduces and eliminates the water part of the equation – thereby protecting your dry pipe or pre-action sprinkler system against corrosion. So next time you see one of these little desiccant packages that you found at the bottom of a bag of beef jerky remember that dry air is at work! … go ahead, you can eat the jerky.

    To learn more about the benefits of dry air as a corrosion mitigation technology comment here or contact us today!

  • Why We Never Recommend Nitrogen for Freezer Room / Cold Storage Sprinkler Systems

    Dry Air vs. Nitrogen for Cold Storage or Freezer Room Sprinkler Systems

    At General Air Products, we are often asked, “Should I Use Nitrogen or Dry Air in freezer rooms and cold storage sprinkler systems?” Our answer – as a manufacturer of nitrogen generators, dry air generators and air compressors - is dry air. Every time.

    There are three technologies available for filling dry pipe and pre-action sprinkler systems – standard compressed air, dry air generators – such as the Dry Air Pac® - and nitrogen generators. General Air Products is the only company in the fire sprinkler industry that manufactures all three of these types of equipment. This puts us in a unique position to speak to the pros and cons of each technology given a specific application. So, the first thing to take away here is that all of these products – compressors, dry air generators and nitrogen generators – have positives and negatives when applied to a dry pipe or pre-action system in any type of building.

    Choosing Your Cold Storage and Freezer Room Air Supply

    Let’s start with the easy one – never use standard compressed air in a freezer room application. When you compress air you also draw in water vapor from the humid ambient air – this vapor collects as liquid water in the tank and some of it continues downstream as vapor. Any water or water vapor sent downstream from the fire protection air compressor in a freezer room system will freeze at the length of pipe that is at the interface of the freezing and ambient area.

    Ice Plug in a Freezer Room Fire Sprinkler System

    (Note that pulling air from the freezer room and then through the compressor does not change this as any air pulled through an air compressor will be heated up in the process.  As this water vapor freezes it will not take long to turn into a sizable ice plug. For this reason, standard compressed air should never be used in a freezer room or cooler.)

    (ALSO NOTE:  A poorly maintained dry air generator (Dry Air Pac®) or a poorly maintained nitrogen generator will cause ice plugs to form in freezer rooms, just like an standard air compressor!)

    So, we are left with a choice between dry air or nitrogen.

    Where is the Corrosion in the First Place?

    Pipe Samples from a Freezer Room Sprinkler System governed by a Dry Air Pac show no signs of corrosion Above: Pipe samples taken from a freezer room sprinkler system governed by a Dry Air Pac for 13 years look like they just rolled off the production line.

    Though both dry air and nitrogen have been proven to mitigate corrosion in dry systems, the thing to remember here is that freezer rooms and cold storage fire sprinkler systems are not prone to corrosion. For corrosion to take place, liquid water in the pipe is required. With both dry air and nitrogen generators, we’re allowing virtually no moisture into the system, and the lack of frequent hydrostatic flow testing leaves us with minimal liquid water ever being introduced.

    Typically, a hydrostatic flow test is done at the commissioning of a dry pipe or pre-action system and then performed annually. This is not the case with most cold storage systems. While the initial hydrostatic test is required, allowances are made for freezer and cold storage sprinkler systems that this test does not have to be performed by running water through the entire system every year – to do so would require the freezer to be turned off each time. Cold storage facility managers will avoid this at all costs.

    If we are not introducing liquid water to the system and the piping system sits in an environment where liquid water cannot exist, then there is little to no cause for concern with corrosion.

    Dry air generators are dramatically less expensive than nitrogen generators in systems larger than 1000 gallons in capacity. If there is little cause for corrosion in a sprinkler system then why should you opt for the more expensive option of nitrogen? This point alone makes dry air the optimal choice, though there are several more to consider. General Air Products still recommends a dry air generator even in the few instances where a nitrogen generator is less expensive – this has to do with the performance of each unit type over time.

    Addressing Air Leaks in a Freezer Room

    One of the biggest issues with nitrogen generation is the lack of supervisory gas flow. In the chart below you can see how dramatically air flow from the compressor is reduced when it goes through a nitrogen membrane versus going through the dry end of a dry air generator like the Dry Air Pac®, or when it is not filtered at all as in a fire protection air compressor. This is a big problem with nitrogen generators in fire sprinkler systems as a whole, but it is of paramount importance in freezer room applications.

    Freezer Room Sprinkler Systems - Air Supply Comparison Nitrogen Generators struggle to keep up with system leak rates due to their inherently lower flow (CFM).

    What the diagram tells us is that a fire protection air compressor has the best supervisory gas flow and can keep up with extreme leak rates. This is because air compressors and dry air generators are sized for 30-minute fill requirements whereas a nitrogen generator that is generating 98% nitrogen is only sized for system maintenance. There has been no real discussion on the leakage rates of dry air pre-action systems over that past many years – air compressors can keep up with them. The reason we need to discuss them now is that nitrogen generators cannot.

    Air leaks in dry and pre-action sprinkler systems will always grow over time. While maintaining 98% nitrogen in a sprinkler system will severely limit the amount of corrosion that takes place, it will not slow all of the other causes of air leaks in sprinkler systems.

    Nitrogen Generators on Fire Sprinkler Systems Have Lower CFM due to the filtration required by multiple prefilters as well as the nitrogen membrane. Nitrogen Generators: the air compressor must feed air through multiple pre-filters and eventually the nitrogen membrane itself - which, along with it's high level of filtration, acts as a bottleneck which strictly reduces air flow to the sprinkler system, in order to produce 98% purity nitrogen.

    Keeping all of this in mind, let’s apply a nitrogen generator to a freezer room…

    Upon install in a newly commissioned sprinkler system a properly sized nitrogen generator should keep up with system demands for pressure (at 98% nitrogen). Time passes, forklifts shake the shelving that contains the in-rack sprinkler system causing permanent leak points to form at threads and couplings. Gaskets dry rot, valves don’t seat properly and all the other day-to-day things occur that cause leaks.

    The nitrogen generator, due to its inherently reduced flow, is running more and more each day to keep up with the pressure loss. Before long, it cannot keep up, and a run time or low-pressure alarm is triggered.

    In most cases, when a nitrogen generator can no longer keep up with the demands of the system you can turn it to air mode and then hunt down all of the air leaks so that you can get it back into nitrogen mode again. A costly and painstaking process in any system, but in a freezer room or cold storage warehouse sprinkler system, it is nearly an impossible one without shutting down the freezer room.

    Ask your service manager about the techniques used to find leaks – spraying soapy water, introducing mint scent – then ask about using those techniques in a freezing environment.

    Referring back to the diagram, you can see the difference between the flow rate of a nitrogen generator and that of a dry air generator – and it is substantial – meaning the need to find and address these leaks will be substantially less with a dry air generator. It can keep up.

    General Air Products’ Dry Air Pac® has been dutifully serving as the air supply in freezer room and cold storage fire sprinkler systems for over 25 years and the issues mentioned here are why it works where other technologies run into costly struggles and freezer room down-time. In addition, dry air is almost always a lower cost solution than a nitrogen generator.

    As mentioned in the beginning of the article, all of these technologies have pros and cons. Standard compressed air is the least expensive but does contribute to corrosion to varying degrees. Nitrogen generators reduce corrosion best where there are large amounts of standing water in the fire sprinkler system, and dry air generators are best applied where there are small amounts of standing water, such as in freezer rooms. Both nitrogen and dry air generators are maintenance intensive – filters must be changed or the units will not perform as designed. In the case of our Dry Air Pac®, one additional step is necessary – the desiccant needs to be changed every 3 years. Dry air can also serve more systems than a nitrogen generator – regardless, we recommend no more than 3 systems per air supply device, not matter which you choose.

    It is for all of these reasons that we definitively tell our customers that they should use a dry air generator on their cold storage or freezer room dry pipe sprinkler systems. Every time.

    If you want to know more about how dry air mitigates corrosion, how and why dry systems grow leaks despite corrosion protection, why you should not put more than 3 systems on one air supply or if you have any other questions about air supply technologies for dry pipe and pre-action fire protection systems please do not hesitate to contact us!

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