Importance

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Abstract

A rate of rise detector assembly (16) for use with explosion suppression equipment (14,18). The detector assembly includes a pressure sensor or transducer (20) and a controller (22). The pressure transducer continuously measures the pressure in a protected area and sends signals representative of the pressure to the controller. The controller samples the transducer every 200 .mu.Sec to obtain a series of successive pressure measurements. The sampled pressure measurements are then stored in a memory table (28) having five positions. Each time the table is filled, the five pressure measurements are averaged to obtain an integrated mean pressure value having a sample time of 1 mSec and then erased from the table so that it can be filled with subsequent measurements. This results in the calculation of a series of mean pressure values each having a sample time of 1 mSec. The mean pressure values are each stored in a line of an ROR (rate of rise) table (34) having between 5 and 25 positions each corresponding to a 1 mSec time period. The mean pressure values are stored in the table starting at the top until the table overflows, at which time the mean pressure values beginning at the top of the table are overwritten with new mean pressure values. When the table has been filled, the latest value written in the table is always the mean pressure value for the most current mSec period and the value below it in the table is always the mean pressure value that was measured 'dt' times before (5-25 mSec before, depending on the length of the table). The controller calculates a dP/dt validation value every mSec by taking the most recent mean pressure value in the table and subtracting the mean pressure value that is in the next lower line of the table and dividing this difference by the dt value. The controller compares the calculated dP/dt values to a pre-determined threshold dP/dt rate and triggers the explosion suppression equipment if any of the calculated dP/dt validation values exceed the threshold rate.

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