sprinklernotes Hydrostatic Testing of Tenant Improvements
The following information was provided: We have a local AHJ that always requires us to pump up tenant improvement projects to 200 psi if they are over 20 sprinklers. We have a waiver/release form we always get signed from the owner and/or GC. It always results in delays and change orders for additional testing time as well as repairs to areas that were not in our scope. You asked the following question: Does NFPA 13 require an existing system to be pressurized to 200 psi when modifications in excess of 20 sprinklers cannot be isolated? In response to your question(s), we have reviewed NFPA 13, Standard for the Installation of Sprinkler Systems, 2019 edition. Our informal interpretation: Our informal interpretation is that NFPA 13 does not require an existing system that cannot be isolated, regardless of the number of sprinklers modified, to be pressurized to 200 psi. A hydrostatic test is required, but only at the system working pressure. When installing portions of the system that can be isolated AND consist of more than 20 sprinklers in the individual portion, that portion shall be tested using the standard hydrostatic test per section 29.7.1.1: 29.7.1.1 Where modification is made to an existing system affecting more than 20 sprinklers, the new portion shall be isolated and tested at not less than 200 psi (13.8 bar) for 2 hours. If that section cannot be isolated, then section 29.7.1.2 applies: 29.7.1.2 Modifications that cannot be isolated, such as relocated drops, shall require testing at system working pressure. While the intent is not directly stated in the body of the standard, the handbook commentary clarifies the intent behind the sections: The requirements of 29.7.1, 29.7.1.1, and 29.7.1.2 address additions and modifications and specify when new piping installations are to be isolated and tested. In many cases, segregating new work from existing work is difficult. To require the entire system to undergo another hydrostatic test when only relatively minor changes have been made is unreasonable and not required by NFPA 13. Where system modifications are made and the piping cannot be isolated, such as relocated drops, NFPA 13 provides some flexibility and permits hydrostatic tests to be conducted at the system’s normal static pressure. In general, existing portions of the system do not need to be subjected to a new hydrostatic test. In general, existing portions of the system do not need to be subjected to an additional hydrostatic test above system working pressure. There is no limit on the number of sprinklers modified throughout the building when they cannot be isolated. This relieves the requirement to subject the existing portions of the system from a new hydrostatic test of 200 psi for 2 hours. A hydrostatic test is still completed but not in excess of the system working pressure. It’s important to understand and be familiar with the definition of “system working pressure,” as it will affect the pressures at which we are required to test the system. 3.3.216. System Working Pressure. The maximum anticipated static (nonflowing) or flowing pressure applied to sprinkler system components exclusive of surge pressures and exclusive of pressure from the fire department connection In addition to the definition of system working pressure, there is handbook commentary that helps clear up any confusion. The term system working pressure applies to the maximum pressure that the system is expected to be exposed to under normal circumstances. All components of the sprinkler system should be rated for operating pressures at or above the system working pressure. Transient pressure spikes (surge pressure) and elevated pressure pumped into the system during fire department operations are not taken into consideration for the purposes of defining the system working pressure. In closing, section 29.7.1.2 is not stating that only relocated drops are exempt from testing at 200 psi. The committee is merely providing an example where testing at system pressure is acceptable. It is impossible for the standard to cover every possible situation that would be exempt, which is why the wording “such as” was used in the section.
