Understanding Standpipe Flow Testing
Today’s buildings are bigger, taller, and more complex than ever before. This leads to many questions on how to properly conduct an NFPA 14, Standard for the Installation of Standpipe and Hose Systems, flow test of a newly installed standpipe system being tested prior to the occupancy of a building. Standpipe system acceptance testing requirements are found in NFPA 14 Chapter 11 and provide guidance on the concept of flow testing acceptance. While building designs are becoming more complicated, the concept of a vertical flow test is simple. We are testing the building standpipe system to verify that it meets the designed system demand pressure and flow found in Sections 7.8 and 7.10.
Standpipe System Demand
So, what is system demand? NFPA 14 defines system demand in Chapter 3, Section 3.3.23, as the flow rate and residual pressure required to deliver the total waterflow rate and minimal residual pressures required from a standpipe system at the hydraulically most remote hose connection. The definition holds the keys to the two items we are seeking to verify in a flow test. The first is total flow and the second is the minimum pressure required through the hydraulically most remote two hose valves.
To verify flow, it is critical to flow water from all the indicated locations noted on the approved plans from each standpipe simultaneously. The flow must reach the maximum requirement of 1000 gpm for a building protected throughout with a NFPA 13, Standard for the Installation of Sprinklers, or 1250 gpm for all others. Each of the valves must be flowing 250 gpm, with the first 500 gpm taken through the hydraulically calculated two most demanding hose valves. This measurement is taken at the top of the most hydraulically calculated standpipe. Each additional standpipe flow is 250 gpm and is allowed at any of the hose connections on the additional standpipe(s). If the total flow is 1000 gpm for a building fully protected throughout by NFPA 13, you would be flowing 500 gpm at the top of the most hydraulically demanding standpipe and an additional 250 gpm from the base of two additional standpipes simultaneously flowing a total of 1000 gpm.
The second requirement is for pressure. All Class I standpipes are required to provide a minimum residual pressure of 100 psi through the two most remote 2 ½ in. hose valves. This pressure is verified during the full flow test through the most hydraulically demanding hose valve. No other pressure verification is required during the flow test.
Single Hose Connections on Lateral Pipe
There is an annex figure and note (A.220.127.116.11.6) specifically intended to recommend that additional flow be taken at the tops of all standpipes when single branch lines are used to extend hose valves on each floor. This is a recommendation by the standard and is not enforceable but is used to highlight that this configuration forms additional standpipes that should be taken into consideration in the hydraulic calculation.
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