A Breakout of a Floor Control Riser Assembly

Today we're breaking into floor control assemblies. The following is a full arrangement for a combination standpipe/sprinkler riser where high pressures necessitate a pressure reducing valve at each level.

While every element in this specific arrangement is certainly not a necessity on every project, here's some considerations that go into the requirements and considerations for a layout like this:

Auxiliary Drain Valve

• Permits faster draining of system (as opposed to only draining inspector's test valve)

Capped Outlets

• Optionally included for testing of Pressure Reducing Valves, when provided (see Pressure Reducing Valve Testing below)

Check Valve

• Can help reduce false waterflow alarms on floor where sprinklers have not activated (NFPA 13 2007-2016 Section A.8.17.1.6)
• Required for a combined standpipe/sprinkler system (NFPA 13 2007-2016 Section 8.17.5.2.2(1))

Drain Pipe

• Size: 3/4 inch for 2 inch system pipe, 1-1/4 inch for 2-1/2 - 3-1/2 inch system pipe, or 2 inch for 4 inch system pipe (NFPA 13 2002 Table 8.15.2.4.2, 2007-2016 Table 8.16.2.4.2)

Drain Valve

• Minimum Size: 3/4 inch for 5-50 gallon system, 1 inch for 50+ gallon system (NFPA 13 2002 Section 8.15.2.5.2, 2007-2016 Section 8.16.2.5.2)

Drain Riser

• Discharge: must be to outside or drain capable of handling the flow (NFPA 13 2002 Section 8.15.2.4.4, 2007-2016 Section 8.16.2.4.4)
• Size: Must be at least one pipe size larger than the largest drain connection tying into it (NFPA 13 2002 Section 8.15.2.4.7, 2007-2013 Section 8.16.2.4.7, 2016 Section 8.16.2.4.8)
• Size with PRV: When serving a Pressure Reducing Valve, the drain, drain connection, and drain piping shall be sized to permit the greatest system demand by the Pressure Reducing Valve (NFPA 13 2002 Section 8.15.2.4.5, 2007-2016 Section 8.16.2.4.5)

Height of Lowest Element

• Objects cannot be more than 4 inches off of a wall unless they are more than 80 inches above the finished floor (ADA 2010 Section 307.2)

Inspector's Test

• Accessible: Must be accessible (NFPA 13 2002 Section 8.16.4, 2007-2016 Section 8.17.4)
• Discharge: Must discharge outside or to a drain capable of handling flow (NFPA 13 2002 Section 8.16.4, 2007-2016 Section 8.17.4)
• Downstream of waterflow alarm (NFPA 13 2002 Section 8.16.4, 2007-2016 Section 8.17.4)
• Orifice: Must have smooth bore, corrosion-resistant orifice with flow equal to or less than one sprinkler orifice on each system (NFPA 13 2002 Section 8.16.4, 2007-2016 Section 8.17.4)

​Pressure Gauge

• Required at each floor control valve (NFPA 13 2002 Section 8.16.3.1, 2007-2016 8.17.3.1)
• Must have a limit at least twice the system normal working pressure (NFPA 13 2002 8.16.3.1, 2007-2016 8.17.3.3)

​Pressure Reducing Valve (PRV)

• Provided to reduce the system pressure such that the working pressure will not exceed a standard 175 PSI listed pressure of the sprinklers, piping, and fittings. PRVs can also be used to limit the system pressure to higher amounts when pressures are allowed to exceed 175 PSI.
• Not required by code, and some have found PRVs to be prone to failure and difficult to test.

​Pressure Reducing Valve (PRV) Testing

• Inspected: must be quarterly (NFPA 25 2014 Section 13.5.1.1)
• Tested: must be partially tested annually (NFPA 25 2014 Section 5.1.3), and fully flowed every 5 years (NFPA 25 2014 Section 13.5.1.2)
• Full flow testing in place: requires pressure gauge on inlet and outlet side of PRV, takes flow measurement using a pitot tube or flowmeter, discharging through the roof manifold on building exterior or through capped outlets provided for testing (NFPA 25 2014 13.5.1.2)

Riser 

• Control Valve for entire riser: Required to permit isolating a riser without interrupting other systems (NFPA 13 2002 Section 8.16.5.2.2(3), 2007-2016 Section 8.17.5.2.2(3))
• Size: Minimum 4 inch, unless hydraulically calculated to permit smaller size (NFPA 13 2002 Section 8.16.5.2.2(2), 2007-2016 Section 8.17.5.2.2(2)).

Sight Glass

• Enables easy verification of water flow for inspector's test.

Supervisory Switches

• Must be tested semiannually (NFPA 25 2014 Section 13.3.3.5.1)

​Union

• Provided to permit exact orifice size of sprinkler for waterflow switch testing.

​Valve (Floor Control Valve)

• Accessible (NFPA 13 2007 A.8.16.1.1.1)
• Electrically supervised or locked (NFPA 25 2014 13.3.1.4)
• Signage must be provided (NFPA 25 2014 13.3.1)
• Tested: annually (NFPA 25 2014 Section 13.3.3.1)

Waterflow Switch

• Tested: quarterly (NFPA 13 2002 Table A.18.1, 2007-2010 Table A.26.1, 2013-2016 Table A.27.1)

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