AU6485080A - Fire extinguishing appparatus - Google Patents
Fire extinguishing appparatusInfo
- Publication number
- AU6485080A AU6485080A AU64850/80A AU6485080A AU6485080A AU 6485080 A AU6485080 A AU 6485080A AU 64850/80 A AU64850/80 A AU 64850/80A AU 6485080 A AU6485080 A AU 6485080A AU 6485080 A AU6485080 A AU 6485080A
- Authority
- AU
- Australia
- Prior art keywords
- actuators
- fire extinguishing
- series
- actuator
- appparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 230000007423 decrease Effects 0.000 claims description 2
- 238000012544 monitoring process Methods 0.000 claims description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 101100360207 Caenorhabditis elegans rla-1 gene Proteins 0.000 description 1
- 101100096030 Oryza sativa subsp. japonica SMOS1 gene Proteins 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000011664 signaling Effects 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 230000001960 triggered effect Effects 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Chemical And Physical Treatments For Wood And The Like (AREA)
- Fire-Extinguishing Compositions (AREA)
Description
FIRE EXTINGUISHING APPARATUS
The present invention relates to fire extinguishing apparatus and more particularly to an electrical circuit for actuatiiig fire extinguishing devices such as sprinkler heads. One way of actuating a sprinkler head is for each head to be provided with an electrically actuable single shot actuator which is used to rupture a seal, for example the quartz bulb, of a sprinkler head to cause water or other fire extinguishing fluid to be discharged from the head. One such actuator is sold under the trade name
Metron by Nobel's Explosives Company Limited of Ayshire, Scotland. Individually, these actuators operate satisfactorily but when used in large numbers and especially when it is desired to actuate a plurality of such actuators using a single trigger signal problems can arise due to the fact that when actuated the actuators can end up either in open circuit or a short circuit state in a random manner. This means that it is possible that only some of the desired number of actuators will actually be actuated which could have disasterous consequences.
In order to ensure that each actuator of a plurality of actuators is operated, one could wire the actuators in parallel but this is an expensive operation and causes difficulties in providing a trigger signal which will meet the manufacturer's specification for a drive signal which is for example, a current of 2 amps with a rise time of 100 m.secs.
Wiring the actuators in series would avoid the problems of cost and drive signal specification but does not itself solve the problem that some actuators may be in an open circuit mode after actuation and before the drive signal current can actuate any further actuators.
The present invention provides fire extinguishing apparatus comprising a plurality of actuator each arranged to be actuated by an electrical signal, the actuators being connected in series, and arranged to be connected to a device for producing the electrical signal characterised in that each actuator has connected in parallel with it, a device whose resistance decreases with increasing current through the device.
In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example with reference to the accompanying drawing which shows a circuit diagram of a fire extinguishing arrangement according to the present invention. The apparatus comprises an electrical circuit for the operation of a number of single shot actuators (gas generators) when connected in series. Each actuator comprises a low resistance electric fuse. The actuators may be used to rupture a seal for example the quartz bulb of a sprinkler head.
The circuit utilises an electrical supply which may typically be 50 volts DC which will operate up to ten actuators in one series chain.
The supply is used to charge a capacitor (Cl) which is used to reduce the effect of source impedance. The capacitor is discharged via/a silicon controlled rectifier
(SCR.l) through a ballast resistor Rl into the series chain of actuators (Al-An) when it is desired to operate the actuators. The silicon controlled rectifier is triggered by the closing of a contact (Si) which may be manually
and/or automatically operated by a fire detection device such as a smoke or heat detector. Across each actuator is connected a current sensitive resistance device
(RDl-RDn) with typical characteristics of high resistance when passing less than 10 milliamps and low resistance when passing 2 amperes. Such a device is a Brimistor.
In order to be able to monitor the continuity of the series chain of actuators, the series chain and ballast resistor form one leg of a D.C. bridge circuit whose other legs are constituted by a variable resistor VR1 and fixed resistors R2 and R3. The power supply for the bridge is provided by the junction between R2 and R3 being connected by one pole of the D.C. supply for the actuators while the junction between the variable resistor VR1 and to series chain of actuators is connected to the other pole of the supply. A diode D is connected in parallel with the supply. Unbalancing of the bridge is detected by a liner operational amplifier AMP 1 whose one input is connected to the junction between resistance R3 at the series chain of actuators and whose other input is connected to the junction between VR1 and R2. The output of the amplifier is fed to an indicator in the form of a light emitting device and a relay RLA1. The light emitting device is preferably a light emitting diode LED 1. The bridge is balanced using the variable resistor VR1 and with the bridge balanced the light emitting diode LED 1 is illuminated and the relay RLA 1 energised. Should any one of the actuators go open circuit due to aging or damage then the effective resistance of the series chain increases as the parallel resistive device is no longer shunted by the relatively low resistance of the electric fuse of the actuator. This change is sufficient t o unbalance the DC Bridge and the operational amplifier switches to extinguish LED 1 (and the signalling relay is de-energised). The monitoring current flowing through the
series chain is limited to less than 10 milliamps - a level which will not operate the actuators or change the value of the resistive devices. A similar indication will be given if the connecting cable in the series chain is open circuited. When actuators are connected in series without shunt resistive devices there is a possibility due to manufacturing tolerances and installation conditions that one electric fuse may rupture before all other fuses have reached sufficient enery to ignite their respective charges. The resistance of the actuators can vary in practice from 0.9 ohm to 1.6 ohm. Also if one or more electric fuse is open circuit the remaining 'healthy' fuses cannot be operated. With this invention in the case of a healthy chain a current in excess of 2 amperes is available with a rise time of less than 100 microseconds. If any one or more electric fuses are open circuit before or during firing then all the 'healthy' actuators may. still be operated. This is due to the parallel resistive device across any open circuit electric fuse rapidly reducing its resistance with the relatively high current now flowing thereby enabling further actuators to operate. The value of the ballast resistor Rl is chosen having regard to the number of actuators in the chain and the desired magnitude of the current in the chain. Also the resistive devices will continue to conduct after operation of all actuators and it may be desired to interupt the supply either manually or by a timer or similar device after some minutes.
Claims (3)
1. Fire extinguishing apparatus comprising a plurality of actuators each arranged to be actuated by an electrical signal, the actuators being connected in series, and means for applying an electrical signal to said actuators characterised in that each actuator has connected in parallel with it a device whose resistance decreases with increasing current through the device.
2. Fire extinguishing apparatus according to claim
1 and comprising a ballast resistor connected in series with said actuators.
3. Fire extinguishing apparatus according to claim 1 or 2, and comprising means for monitoring the continuity of said series connected actuators.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7939517 | 1979-11-15 | ||
| GB7939517 | 1979-11-15 | ||
| PCT/GB1980/000197 WO1981001369A1 (en) | 1979-11-15 | 1980-11-14 | Fire extinguishing apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU6485080A true AU6485080A (en) | 1981-06-03 |
| AU535267B2 AU535267B2 (en) | 1984-03-08 |
Family
ID=26273554
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU64850/80A Ceased AU535267B2 (en) | 1979-11-15 | 1980-11-14 | Fire extinguishing appparatus |
Country Status (1)
| Country | Link |
|---|---|
| AU (1) | AU535267B2 (en) |
-
1980
- 1980-11-14 AU AU64850/80A patent/AU535267B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU535267B2 (en) | 1984-03-08 |
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