The Parking Garage Effect: Fire Sprinkler Corrosion, Blocked Pipes, and More

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parking garage

Parking garages see it all.  They feel like a sauna in the summer.  They’re frigid in the winter.  They get pounded with rain and sleet and snow.  Parking garages are tough, so the equipment inside them needs to be durable and made for the environment. 

Fire protection is a delicate thing.  If the pitch of the pipe is off, you get sitting water.  Sitting water is the enemy.  It is the start to a frozen pipe that can burst, corrosion that can eat the pipe away, or scales sloughing off the metal – all of which can impede the fire sprinkler activation in the event of a fire.  If there is one time where you definitely want your fire protection working perfectly, that is when there is a fire.  Wouldn’t you say? 

The main cause of fire protection failure is obstruction.  We’re going to go over what causes an obstruction, how the obstructions can affect your fire protection, and how we can remove the obstruction to get your fire sprinkler system back up and running at full capacity.

What causes obstructions?

Obstructions can be organic or inorganic caused from microbiologically influenced corrosion (MIC), pipe scale, or ice.  All three of these can block the water flow from getting to the fire sprinkler in the event that it gets activated, causing a failure. 

There are four main causes for organic or inorganic obstruction.

4 causes of obstruction 

1)       Contaminated Water – Parking garages have air pollution particulates.  Think of all of those car exhausts in one place.  The particulates will get into standing water that has accumulated due to poorly pitched pipe.  As the pure water evaporates, the contaminated water stays put.  The concentrated contaminated water will increase pipe corrosion and changes the pH balance of the water.

2)       pH Balance – While parking garages have dry-pipe fire sprinklers to avoid freezing temperatures, an improperly pitched fire sprinkler pipe can have sitting water.  In fact, that is quite common.  Sitting water can cause many problems in a parking garage fire sprinkler system (frozen pipes, corrosion, scale), but if the water’s pH balance isn’t just right, it can make things worse.  A pH balance of 8+ is too alkaline and can cause scale to form.  Water that is too acidic, under 8 on the pH scale, when mixed with oxygen and contaminants (which run amuck in parking garages) can cause the metal of the pipes to deteriorate through chemical or electrochemical reaction.

3)       Freezing Temperatures – The water that sits silently in your fire protection pipes can freeze in the cold winter months.  Once it begins to warm up, the expanded ice melts and cracks become visible.  This will change the air pressure of the system, causing the valve to trip.  The pipes will begin to fill with water and the crack will leak.  

4)       Warm Environment – While cold days bring the fear of frozen pipes, warm days breed microbes.  The microbial growth will cause differential aeration (oxygen concentration cells).  When these cells are trapped between scales and the metal pipe, it speeds deterioration of the pipe.  For every increase in temperature of 25-30 degrees, the corrosion rate doubles.

How do obstructions affect fire protection?

Obstructions in the fire protection system are serious.  They can impede the water flow to the fire sprinkler head in the event that the fire protection activates.  The pipe scale can migrate when the water flows and clog up a number of areas in the fire protection system.

It’s not possible to know if there is sitting water in the fire protection systems, so be proactive. 

1)      Schedule Due Diligence Inspection – This inspection will verify that the pitch is correct.  If it isn’t, your fire protection provider can re-pitch it and install drip drums.  During tests or activation, water can sit, even in a perfectly pitched pipe, so drum drips should be installed.  Have the drum drips drained weekly or monthly, to ensure the water is removed.

2)      Conduct Trip Tests Every 3 Years – Every three years a trip test should be conducted on dry-pipe sprinklers.

3)      Per NFPA 25, Schedule 5 Year Inspections – 5 year inspections are the only inspections that go inside the pipe.  The inspection covers 4 points:  system valve, riser, cross main, and branch line.  If any of the following are found, an obstruction investigation will be the next step:

·         Defective intake for fire pumps that take suction from an open body of water.

·         Obstruction materials discharged during routine water test.

·         Foreign materials were found in the fire pumps, dry pipe valves, or check valves.

·         Foreign material was found during the drain tests or plugging occurred at the inspector’s test connections.

·         Unknown material can be heard in the system.

·         Plugged sprinklers are discovered.

·         Sufficient foreign organic or inorganic material is found in the pipe.

·         Failure to flush yard piping or surrounding public mains following new install or repair.

·         Record of broken public mains in the vicinity.

·         Abnormally high false tripping of dry pipe valves.

·         System returned to service after 1+ years of shutdown.

·         There is evidence that the system has sodium silicate or highly corrosive fluxes in copper systems.

·         A system has been supplied with raw water via the fire department connection.

·         Pinhole leaks uncovered.

·         50% increase in the time it takes water to travel to the inspector’s test connection from the time the valve trips during full flow trip test of a dry pipe sprinkler system when compared to the original system acceptance test.

How do obstructions get removed?

Let’s just say, you had your 5-year inspection.  The inspector found scaling in your fire sprinkler pipes.  Now what?  First, an obstruction investigation will take place.  This will uncover where the foreign material is located.  Second, a flushing will be scheduled.  The flushing is just as it sounds, the fire sprinkler service provider flushes out any obstructions.  You can view a video of that here.

fire sprinkler corrosion 

You don’t want to have to schedule another obstruction investigation and flushing in five years, so how do you prevent it? 

1)      Keep up with maintenance – follow NFPA 25’s guidelines for maintenance for dry-pipe fire sprinklers. 

2)      Install drum drips – install drum drips if your system does not already have them and have them drained throughout the winter months.

3)      Schedule inspections – While following the maintenance schedule is important, it is even more important to have your inspections scheduled like clockwork.  Quarterly, annually, 3-year (for dry-pipe), and especially the 5-year inspection.  For obstruction protection, the 5-year inspection is the most important because it is the only inspection that goes inside your system. 

4)      Install a nitrogen system – The nitrogen eats away the oxygen, which causes the scaling and corrosion.  It will stop the continuation of corrosion.

Parking garages breed deterioration, corrosion, and blockages.  By scheduling preventative maintenance and keeping up with the inspection schedule, you can minimize the risk of obstructions and potential costly repairs.  F.E. Moran Fire Protection can analyze your fire sprinkler system to ensure that it is working at optimal performance à Click Here to Contact Us!

Recommended Reads

www.femoranfp.com/.../FEM_SPRINKLER_ITM_Requirements-2011_R0_ FINAL_FP.pd
File Format: PDF/Adobe Acrobat
13.5.2.2. 5 Year (cont.): Hose Racks Pressure Reducing & Relief Valves. Test. NFPA 25. 13.1.1.2. 13.5.3.2. Hoses. Test. NFPA 1962. -. ObstructionInvestigation  .
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