Is an obstruction investigation required every five years?

There are two activities that are related to obstructions in Chapter 13 that require our attention. The first is an investigation that is actually more of an “inspection” as described in Section 13.2.1 that must be conducted every five years. While the sprinkler system is shut down for the purpose of internal valve inspections (See Table 12.1), the flushing connection at the end of one main and a single sprinkler at the end of one branchline for the purpose of inspecting for the presence of foreign organic or inorganic material.

In Section 13.2.2 a more comprehensive obstruction “investigation” must be conducted when any of the 14 conditions listed in that section are present. This more comprehensive obstruction “investigation” is conducted by internally examining the following four points in a system: system valve, riser, crossmain,  branchline and is only required when one of the 14 problems listed in Section 13.2.2 is present. This obstruction investigation is not a routine procedure; it is only needed when a problem exists. If any obstructing material is found, a complete flushing program must be conducted to remove any remaining obstructing material.

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Quick FAQ....

I have a standpipe system with two risers. The original design indicates a total flow of 750 gpm (2839 Lpm). Am I required to flow this much water for the five year flow test?

No. When conducting the five year flow test, one riser is tested at a time. Therefore, the flow should be a total of 500 gpm (1892 Lpm), 250 gpm (946 lpm) for each of the two topmost outlets.