The question to Cobb County: Can you please provide me with the written requirements for flow tests in Cobb County, so that I can pass them on to our membership?
The answer from Captain Robert J. Bennett, Deputy Fire Marshal/Plans Review:
The requirements are fairly straight forward.
The submitted figures need to include the static pressure, residual pressure, pitot reading in PSI, flowed GPM and projected availability at 20 PSI.
The differential between the static and the residual must be 10 % of the static pressure The pitot reading needs to be 50 PSI or lower.
Due to the pressures we carry in Cobb we frequently get report that have little or no change between static and residual pressures. To create a greater drop in pressure the testing contractor should open additional nozzles to increase the flowed GPM and cause a resultant increased drop in residual pressure.
Hope this helps, if you have questions let me know.