We prefer wet-pipe sprinkler systems over dry-pipe systems for a handful of reasons: lower cost, no pipe slope requirements, potentially less points of drainage, can locate inspection & testing at the riser, less maintenance, testing and inspection requirements, no power needs, less noisy, and much less potential for corrosion. However, when dry systems are needed, there's several issues to consider for the end-user. Noise Complaints For owners who are not associated with the intricacies of design and maintenance of dry systems, the most frequent compliant we hear about is with the noise associated with the dry system air compressors. Leaky Systems Dry-pipe systems are fed with pressurized air by a compressor. The compressor run-time frequency and duration is directly attributed to the amount of leakage in the system. Some people directly attribute the leakage of the system to the quality of installation due to the final tightness of fittings. Air injected into a leaky system develops two problems. The first is increased potential for corrosion as fresh air naturally contains water moisture and oxygen, the two ingredients for corrosion. Air that feels comfortable to us offers sufficient products to encourage corrosion, and leaky systems tend to fail with corrosive issues much earlier in their lifetime. The second issue is noise. While it sounds trivial, noise isn't for the employee whose cubicle is next to the riser room. If leaky systems cause issues, why don't contractors prevent or fix leaky systems? Fixing Leaky Systems Once a system is installed and pressure tested to meet minimum standards, finding points of leakage is very tedious and time consuming. Just finding a few leaky fittings requires inspecting every joint and adjusting connection points. Needless to say, if a system isn't installed with tight fittings it becomes a very time-intensive and costly proposition to fix. Lessening Leakage and Noise in Design As a designer I naturally have less impact on the quality of installation than I do of the design, and there are several ways to help lessen the impact of leakage and noise. Leakage requirements could be mandated to be leak less than prescribed code minimums. I've found this route doesn't exactly make good friends of contractors. Noise can be reduced in a number of ways. First is to use tank-mounted air compressors in lieu of riser-mounted air compressors. Tanks act as a pressurized reserve, where they can reduce the frequency which compressors run in order to supply the system. Mounting to the tank also vibrates the tank, and not the piping network that runs through a building. Vibration on the pipe network requires absorption by the building, which contributes to higher ambient noise. The base of the tank can be isolated with vibration isolation (often rubber pads), again helping to reduce vibration transmission to the building. The downside to tank-mounted compressors is an increased cost and needs for additional floor space. Another important consideration is where the compressor is located. Often the allotted space for risers are determined architecturally, but upfront coordination and planning to help prevent locating dry riser rooms next to normally occupied spaces can have major benefits. If the dry riser room must be near occupied spaces, consider requesting insulation within walls or acoustic panels to help absorb sound. Quiet-Series Air Compressors Lastly, one of my favorite products to hit the market in the last couple years offers a major solution to the noise issue. I'll start by saying I don't have any family or friends that work for General Air Products. They have not reached out to me to offer any money (although if you're out there General Air I'd be happy to share an address for a check). That disclaimer aside I really love the Q-Series (Quiet Series) General Air Compressors for fire sprinkler systems. The Q-Series air compressor model can be tank-mounted and is significantly quieter than standard air compressors. The noise for the Q-Series have reduced noise by 20 dBA from the previous 80 dBA of standard oil-less compressors. For drywalled, carpeted rooms the effective sound from the Q-Series compressor is only slightly higher than ambient noise levels of a typical office. The video above (by General Air) shows the difference in compressor noise. Needless to say it would be great for applications in hospitals, schools, offices, hotels, retail, nursing homes, and other areas sensitive to noise. We've found these to be a great solution to a common and intrusive issue of noise with dry risers near occupied spaces. Is this article helpful? Consider subscribing to these weekly articles or sharing it with a colleague who might benefit.
Jim Williams
1/18/2018 08:31:28 pm
very interested in the Q style air compressor.
Kelly Frazier
1/30/2018 06:56:39 pm
We have a dry system in all 11 of our residential apartment buildings. The system is about 18 years old and the pipes are constantly leaking. Any idea what we can do to prevent so many leaks or seal the pipes from the inside to slow down these pin hole leaks. Any help would be appreciated as we are spending over $1000 month making repairs in the attic!
JOE MEYER
2/5/2018 06:34:15 am
Is the leakage due to continued corrosion? If so, you may consider a nitrogen inertion system. They can be retrofit and simply fill dry systems with 98%+ in nitrogen instead of oxygen. They essentially inhibit corrosion and stop any further deterioration from happening. I had no idea that there were some compressors that could operate without making a sound. It is important to remember that taking the time to do some research and understand your own needs can help you find the best one for your needs. We are planning on getting an air compressor that can help us keep the tires on our cars properly inflated, so I'm glad I found your page. 3/14/2018 03:46:09 pm
What are the typical space requirements for each of the options? How does the Q-Series compressor size compare to a non Q-series compressor?
Bruce O'Such
1/30/2019 04:29:05 pm
Very much appreciate this post. We recently moved into a townhouse in a 5 unit complex. It consists of 2 buildings, each of which has both a wet and dry system. Our unit's basement houses the equipment for one building and we have found that the riser mounted compressor goes off approximately every 3 hours for 3-4 minutes. It's incredibly noisy. The option of a Q Series, tank mounted compressor is appealing, but I wonder if there's a significant leakage problem we should focus on first, given the short intervals. Thanks so much
Joe Meyer
1/31/2019 06:11:49 am
Great question Bruce! Just posted it for daily discussion as it's a good topic. You can see the thread here: https://www.meyerfire.com/daily/compressor-runs-frequently-too-much-leakage 6/26/2019 09:14:15 am
I live in a 3 story walkup on the 3rd floor. The compressor goes off very regularly in the winter maybe every 20-30 minutes. I complained to the property manager and they claimed it was normal. I believe it is not functioning properly is that a fire hazard? Comments are closed.
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+ Unsubscribe anytime AUTHORJoe Meyer, PE, is a Fire Protection Engineer out of St. Louis, Missouri who writes & develops resources for Fire Protection Professionals. See bio here: About FILTERS
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