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Happy 2012 to everyone.  May this year be the best yet!

 

Continuing on with the Residential Code sprinklers requirements and completing this important topic:

So far we reviewed the “conventional” fire sprinkler systems found in the majority of residential single-family dwellings and duplexes.  We also reviewed the simplest method for determining the sizes of the piping and the factors that enters in determining the locations of the sprinkler heads and restrictions and rules governing the installation. 

There are (of course) other types of systems available and other methods of calculations, albeit not outlined in the California Residential Code.  One very common system is that called the “Network” system.  This is a system that must be “listed” and installed as a system without modifications or alterations.  It is a type of a “multi-purpose” system that often uses 1/2” piping to serve both the domestic and fire systems.  Note that the code requires a minimum 3/4" piping.  Therefore, it follows that the system must be installed as specified by the manufacturer and the listing to justify the use of a lesser size pipe.  In this system, each sprinkler is supplied by water from at least 3 separate paths and with a minimum 4 paths if a plumbing fixture is served.  The system relies on a network of piping to supply each sprinkler head and therefore requires less flow from each line, thus decreasing the friction losses and allowing the use of a smaller pipe sizes. 

The system must be calculated using hydraulic calculations and unless an approved computer program is used, the calculations are very tedious and would require trial and error until the flows in each pipe is determined and the predicted total pressure losses are calculated. 

There is an additional requirement for that system that allows only one insert tee in each pipe section between sprinklers to serve a domestic fixture(s).  (Please note that the example shown in NFPA 13R is incorrect and does not comply with this last requirement.)  The following figure corrects this item and shows a system in compliance with all the requirements.

 

 

 

 

There is also other types of systems, such as the “loop” multi purpose system, which usually requires computer type calculations.

 

 

 Other requirements for all system installations specified in the code are:

 

1.         The contractor must leave an owner’s manual at the site that provides detailed information on the system and how to maintain it.

2.         There must be a sign at the shut-off valve (control valve) that reads:

 

“Warning, the water system for this home supplies fire sprinklers that require certain flows and pressures to fight a fire. Devices that restrict the flow or decrease the pressure or automatically shut off the water to the fire sprinkler system, such as water softeners, filtration systems and automatic shutoff valves, shall not be added to this system without a review of the fire sprinkler system by a fire protection specialist. Do not remove this sign.”

 

Now the next few items pertains to the minimum information required on the plans submitted for approval:

 

–     Address, name of owner, builder or responsible party

–     Size & type of domestic line, including length of pipe to city main

–     Water meter size, location of valve, other devices, including sizes and losses through them (include manufacturer’s data sheets)

–     Current static water pressure (minimum & maximum)

–     Model, manufacturer, temperature rating, orifice size and spacing requirements of sprinklers, including K-factor, GPM & pressure for each type used

–     Type of pipe, sizes on all branches and main with lengths of each segment (include fittings if prescriptive method is not used)

–     Hanger spacing and sprinkler bracing

–     Riser detail (if any)

–     Installing contractor information

–     Hydraulic calculations

–     (Additional details if a single source)

 

The next few items pertains to inspection of the system:

 

Inspection before concealment:

 

–     Verify C-16 contractor’s license if Stand-alone or C-16 AND C-36 license if Multipurpose system

–     Verify sprinkler manufacturer with plans & coverage/spacing of sprinklers

–     In all areas required (note exceptions-furnace in attic)

–     Obstructions (fans, ceiling lights)

–     Proximity to heat source (kitchen, fireplace, warm air registers)

–     Correct temperature rating (skylights, attic)

–     Pipe size as per plan (could be computer program)

–     Total pipe’s developed length must matche the plans/calculations

–     Non/metallic pipe (CPVC or PEX) listed for fire sprinkler use

–     Pipe support as per CPC (also supports that would prevent movement when sprinkler operates)

–     Pipe tested as per CPC

 

 

Inspection-Final:

 

–     Sprinklers not painted, damaged or hindered

–     If pump is part of operation, pump starts automatically when system demand (use drain to test this feature) and will run for the duration (7 or 10 minutes)

–     No additional devices have been installed (pressure reducing valves, water softeners, water filters, or others, if not part of the original design)

–     The sign at the shut-off valve is installed and owner manual is present

–     Manual available to occupant with the following information:

        Monthly inspections of all valves to ensure they are open

        Monthly inspections of pumps, tanks, gages, if any

        Ongoing visual inspection of sprinklers for obstructions, paint, etc.

        After a paint job check the sprinklers (cover with a bag while painting)

 

 

This completes this topic and I hope to provide you with other interesting topics and discussions during the New Year.

 

Thank you for your interest and have a great year.