The present invention relates to the detection of the actuation of a fire sprinkler, for example, in tests related to research in controlling fires or in actual fire sprinkler installations.
In fire tests for evaluating the effectiveness of a fire sprinkler or arrangement of fire sprinklers, it is helpful to know the precise time of actuation of the sprinkler or sprinklers. The present art in detecting the operation of a fire sprinkler, as in fire testing, is based on the sprinkler being part of an electrical circuit that is interrupted the instant that the heat responsive element of the sprinkler actuates upon exposure to a fire. In one type, electrical wires extend to a heat fusible link that melts in response to the heat of a fire and allows water to flow. The link and wires are part of an electric circuit that is broken when the link melts, whereby the operation of the sprinkler can be detected. In electric sprinkler actuation detection devices generally, the electrical connections at the sprinkler may interfere, or be perceived to interfere, with the actuation event itself or with the water spray produced by the sprinkler. The interference with the water spray can be either in the region of the so-called deflector that generates the drops or in the spray formation region below the deflector.
The system of detecting sprinkler actuation according to the present invention does not in any way interfere with the actuation event, the water flow or the spray formation. The sprinkler actuation detection system according to the present invention has no connections or other structure at the sprinkler, either in the region of the deflector that generates the drops or in the spray formation region below the deflector. It has no structure that interferes, or is likely to be perceived to interfere, with the actuation event itself or with the water spray produced by the sprinkler. Instead, the sensing of the first and second fluid pressures is performed solely with structure entirely outside the space required for actuation of the sprinkler and the space occupied by fluid issuing from the sprinkler outlet.
In order to detect sprinkler actuation, the method and apparatus according to the present invention use the pressure difference between a high pressure port in fluid communication with a region of larger flow cross section and a low pressure port in fluid communication with a region of smaller flow cross section, wherein both regions are in a path taken by fluid flowing through the sprinkler when the sprinkler is actuated. Before actuation of the sprinkler, the fluid pressures at the high pressure port and the low pressure port are substantially the same as one another. However, after actuation, the fluid pressure at the high pressure port is higher than the fluid pressure at the low pressure port, and this change in the relationship of the two pressures from before actuation to after actuation is detected in accordance with the present invention.
The method and apparatus according to the present invention are insensitive to pressure transients caused by the operation of other sprinklers, because the high pressure and low pressure ports are sufficiently close to one another that they are affected by pressure changes at the same time or virtually the same time. As a result, there are no false indications of sprinkler actuation from a transient increase in fluid pressure reaching one port before the other and causing a temporary difference in fluid pressure at the two ports.
As can be seen from
A high pressure port 18 is provided in the wall of the inlet pipe section 12 upstream of the sprinkler 10, so that the fluid in the pipe 16 can be accessed at that point, and the pressure of the fluid can be sensed by an appropriate instrument. For example, the high pressure port 18 can be connected by a fluid conduit 19 to a pressure transducer 20 that can sense the pressure at the port and provide an electrical signal whose strength is proportional to the pressure sensed. The high pressure port 18, the fluid conduit 19 and the pressure transducer 20 comprise a first pressure sensing arrangement.
A low pressure port 21 is provided in a wall of the sprinkler 10, in a side branch 22 that has a smaller flow cross section than the inlet pipe section 12, so that the fluid pressure in the sprinkler can be accessed at that point. The low pressure port 21 can be connected by a fluid conduit 23 to a pressure transducer 24. The low pressure port 21, the fluid conduit 23 and the pressure transducer 24 comprise a second pressure sensing arrangement.
The pressure transducers 20 and 24 are connected by, for example, wires to a computer 25 or other recording instrument. In the embodiment illustrated in
The ports 18 and 21, the transducers 20 and 24, the fluid lines 19 and 23 connecting the ports to the transducers, the wires connecting the transducers to the computer 25, and the computer itself are positioned above the outlet of the sprinkler 10 that directs the fluid to the space around the sprinkler. In fact, all of the structure used for sensing and comparing the fluid pressures is entirely outside the space required for actuation of the sprinkler and the space that will be occupied by fluid issuing from the sprinkler outlet when the sprinkler actuates. As a result, the present invention avoids interference with, and the perception of interference with, the actuation event itself and the fluid spray produced by the sprinkler.
The pipe 16 may contain stagnant water or water flowing to open sprinklers at other sprinkler sites. With stagnant water, the fluid pressures at the high pressure port 18 and the low pressure port 21 are the same, except for minute differences due to hydraulic heads associated with differences in elevation. Even with flowing water, which is separated, at an interface designated in
In the embodiment of
It will be apparent to those skilled in the art, and it is contemplated, that variations and/or changes in the embodiments illustrated and described herein may be made without departure from the present invention. For example, the differential pressure transducer 47 of the embodiment of