Noisy fire system compressor

[zenocchio]

I'm wondering if someone can recommend a solution to my issue.

I live in a three storey building and the garage and attic have a dry sprinkler system that is kept under pressure by a small compressor. Every time the compressor kicks in it can be heard through out the building as the noise travels through the cast iron pipes. The compressor is bolted to the ground on some vibration isolators and there is a flexi connection to the 4" cast iron line.

My next step will be bracing the 4" line with more supports, but that is all I have.
Any suggestions on how to tone it down?

Cheers

 

[72Anthony]

Is there enough slack in the flexible connection?

Sprinkler system piping isn't usually cast iron...too bad in this case because cast iron is good at absorbing vibration. It's most likely plain steel. They do make external insulation for absorbing vibrations and the sounds of flowing liquids. The insulation can have a self stick adhesive or be held in place with straps.

I would call some local sprinkler contractors and get their advice...they may have encountered this issue before.

 

[slowzuki]

If it's running more than a every few months in a small system you are getting leaks. Once it starts running much it is pumping lots of fresh oxygen and water into your dry system and will accelerate corrosion in the piping. Usually ends with pin holes in bottom of pipes popping open and compressor running full time or a big pinhole pops and the valve trips. In the winter this is a mess if it freezes.

I would get the system checked over for leaks.

 

[rlitman]

Exactly. Fix the leaks.
The dry system compressors at my office only run after a flow test. If the pressure dropped enough for them to run at other times, it would trip an alarm.

 

[zenocchio]

Thanks for the input. I am sure that there are few leaks in the system but unfortunately these are not in the exposed areas. The leak must be in the stack rising to the attic, that is buried in the inner walls. No way I can open them up. Hence the corrective measure [emoji6]

 

[Bigredball90]

<--Fire sprinkler inspector

Those few leaks will be exposed when the system trips and the water blows holes through the sheet rock
A leaky system will obviously run more often and make more noise. A good solution might be to get an air compressor with a tank instead of a tankless unit their notorious for making noise. The pipes should be black steel not cast iron. Got any pics of the system I like to see different ones from around the world/country. Best bet is get ahold of a good local company that can get you guys set up.

O yea I believe NFPA 13 says compressor are hard piped and hard wired. Though we frequently see them flexed in. One new inspection has stainless hot and cold lines for a washer hooked into two systems

 

[LS6 Tommy]

If it's running more than a every few months in a small system you are getting leaks. Once it starts running much it is pumping lots of fresh oxygen and water into your dry system and will accelerate corrosion in the piping. Usually ends with pin holes in bottom of pipes popping open and compressor running full time or a big pinhole pops and the valve trips. In the winter this is a mess if it freezes.

I would get the system checked over for leaks.

Gold Star!

Tommy

 

[Milton Shaw]

Fix the leaks, get a quieter compressor would be the smart things to do. I wonder if a dry nitrogen system would work were the pressure is supplied by nitrogen tank and regulator, but you would have to have backup and sensors to report tank fill levels. If you loose pressure the system would fill with water and set off alarms and may make a mess depending on where the leaks are. Either way your sprinkler company should be able to fix the problems.

 

[Bigredball90]

Nitrogen systems are big $$$$, and wont fix his current leaks. Could be as simple as the regulator having a piece of trash in it as well.

 

[zenocchio]

I'll call someone in. Hopefully they will be able to trace the leak quickly

 

[Bigredball90]

Its never quick... The easiest way to find the leak is to fill it with water and wait for the drips. But this time of year its not a good idea.
How often does the compressor run? If its once a day thats not horrible but multiple times a day is.

 

[matt_i]

My Dad has one (from my grandfather) and a friend had one...both are compressors that run really slowly and produce minimal air volume...putt putt putt putt like the idle from a golf cart is the sound rather than a cacophony of rapid compression. In other words, belt driven compressor but dial down the pump speed via changing sheave diameters. There are some considerations relative to the splash lube so there is a minimum speed, the manufacturer might have it on their pump curve chart.

One way to get rid of the sound = pressure pulsations is to artificially restrict the flow. Which is good because you don't really care about that unless leaks get large, but you will know it then Several quick connects in series would be a way I'd try to cobble that together and see how much it helps. Or choose a very small pipe diameter, like 1/4" NPT.

 

[Bigredball90]

Air compressors cannot be changed from their UL listing, and whatever air compressor is used must be able to fill the system within 30 minutes.

But I go to allot of places that the pumps dont come close to filling it in 30 minutes. Again contact fire sprinkler contractor dont do it yourself, it will make you liable for the building and the lives within.

 

[NUTTSGT]

But I go to allot of places that the pumps dont come close to filling it in 30 minutes. Again contact fire sprinkler contractor dont do it yourself, it will make you liable for the building and the lives within.

Very good information right there.

 

[Norcal]

Air compressors cannot be changed from their UL listing, and whatever air compressor is used must be able to fill the system within 30 minutes.

But I go to allot of places that the pumps dont come close to filling it in 30 minutes. Again contact fire sprinkler contractor dont do it yourself, it will make you liable for the building and the lives within.

This is good advice.

It's foolish to work on a fire sprinkler system without proper qualifications, license(s), and liability insurance.