Potter VSR Series VSR-S Series FrictionLossMemo

February 28 2017 13 2016 23.4.4.8.1 I requires that the friction loss across vane type water flow switches 2 inches and smaller be in the fire sprinkler hydraulic calculations As each community County State or local AHJ adopts this standard can expect to receive telephone calls related to this topic Potter Flow Switches products are manufactured and to UL Standard 346 Standard 346 allows a maximum pressure drop of 3 psig 20.7 kPa for flowswitches up to and including 4 and 1 psi in 5 and larger Potter flow switches meet or improve upon that requirement actual friction loss may be substantially less than the UL requirement Field testing may be used to verify this in the absence of field testing using the 3 psig 20.7 kPa figure is a conservative approach response is consistent with the requirements of NFPA 13 24.4.4.7 24.4.2.7 shall be used to determine equivalent length of pipe for fittings and devices unless manufacturer test data indicate that other factors are memorandum is not confidential and may be distributed as needed Henke CET Manager Products Division Electric Signal Company LLC St Louis MO Phone 800 325 3936 www pottersignal com PAGE 1 OF 1 Loss Technical Bulletinfirealarmresources com