A Method Research Of Sensitivity Test For Recessed, Flush And Concealed Sprinklers

Research was conducted to develop plunge test procedures to evaluate the thermal sensitivity of recessed, flush and concealed sprinklers. Such sprinklers can not be assumed to be covered directly by the RTI concept, primarily developed for sprinklers fully exposed to the hot gas flow generated by a fire. The categories of recessed, flush and concealed sprinklers considered in this study were of pendent type, except for some recessed sidewall sprinklers. Fifteen full-scale fire tests were first conducted to compare the response times of recessed, flush and concealed sprinklers with fully exposed standard and quick response pendent sprinklers. Sprinklers from five manufacturers were used in the fire tests. The fire source in all but one of the tests was a 130kW heptane (0.46m diameter) pool fire. In one fire test the fire size was approximately doubled (0.6m diameter heptane pool fire). In addition to sprinkler response times, gas velocity and gas temperature near the sprinklers were measured in all tests, along with the static gas pressure at the ceiling level in the room center. The temperature of a 100ml volume of water in the pipe connected to each sprinkler was also measured. The ceiling flow and water temperature measurements were used to calculate the response times of pendent sprinklers having the maximum allowable thermal response parameters (RTI and C) under the ISO 6182-1 automatic sprinkler standard. From the analysis of fire test results, the sprinkler response time consistent with ISO requirements were determined.Plunge tests were then conducted in the plunge test tunnel with the sprinklers same with those used in the fire tests. A special plate to mount the recessed, flush and concealed sprinklers in the plunge test was fabricated. The plate was fabricated with a closed plenum to contain the portion of the sprinkler that would typically be mounted above the ceiling in normal installation. A comparison of fire test results with plunge test results indicated that special designed plunge tunnel cover should be used in plunge test for recessed, flush and concealed sprinklers .Ceiling pressures generated by the fire needed to be simulated in the plunge test. This was accomplished by evacuating the plenum of the mounting plate while monitoring the pressure difference between the plenum and the plunge tunnel test tunnel under the mounting plate. Based upon a comparison of the results of the plunge tests and the fire tests, plunge test requirements and methods were developed for standard and quick response, recessed, flush and concealed sprinklers.