Measuring water flow rate for a fire hose using wired accelerometers for smart fire fighting

Abstract

A wired sensor network was created to measure water-flow rate in a fire hose. An integrated electronic piezoelectric (IEPE) accelerometer was chosen as the sensor to measure the flow rate based on the vibrations generated by water flowing through a fire hose. These sensors are small, lightweight, and they can be attached to the outside of the hose, not obstructing the water's flow path. A relationship was determined between the flow rate of the water and vibration detected by the accelerometer for a range of flow rates. The raw acceleration signal was used to calculate two metrics: the dominant frequency and the standard deviation of acceleration. In a future study, the relationship between the dominant-frequency metric and the flow rate will be applied to a wireless accelerometer network. The relationship will be used to determine the real-time fire hose flow rate critical for improving situational awareness on the fireground.

Measuring water flow rate for a fire hose using a wireless sensor network for smart fire fighting

“…For relatively rigid pipe, previous research has shown a decreasing dominant frequency with increasing flow rate [8,13,25]. A similar relationship was also found for flexible fire hose in our previous research [23]. Dominant frequency was therefore chosen as the primary metric to determine flow rate.…”

“…Standard deviation of acceleration increased as flow rate increased in rigid pipes [8][9][10][14][15][16]. This relationship was found to be similar for flexible fire hose at lower flow rates, from 0 LPM to at least about 300 LPM (80 GPM), however at higher flow rates, above 300 LPM (80 GPM), the standard deviation of acceleration became unpredictable, often peaking and decreasing [23]. The bell-shaped curve therefore made the standard deviation of acceleration metric not suitable as the only metric for determining the flow rate in a flexible fire hose.…”

“…A detailed literature review was included in the previous technical report [23] describing past work focused on detecting vibration from flowing water in relatively rigid pipe using sensors like accelerometers [24]. Standard deviation of acceleration increased as flow rate increased in rigid pipes [8][9][10][14][15][16].…”

“…Three accelerometers collected data from the Front, Mid (middle) and Back locations on the hose for the following two different series of tests (Test 5 and Test 6). The wired sensor network tests from the previous report were labeled as Test 1, Test 2, and Test 3 [23].…”

“…Each accelerometer was connected to a wireless node by a coaxial cable with 10-32 connectors. Some wireless nodes may include an embedded sensor, however for this study, the same accelerometers were also used for the wired sensor network in a previous study [23]. The number of wireless nodes used in the wireless sensor network affects the data sampling frequency, data collection time, and interval between data collection times.…”