AU6547894A

AU6547894A - Method of operating a sprinkler installation and a device for executing the method

Info

Publication number: AU6547894A
Application number: AU65478/94A
Authority: AU
Inventors: Hakan Ungerth
Original assignee: HTC I AMAL AB
Current assignee: HTC I AMAL AB
Priority date: 1993-04-30
Filing date: 1994-04-25
Publication date: 1994-11-21
Also published as: WO1994025113A1; EP0696218A1; JPH07116281A; TW309437B; SE501398C2; JP3335469B2; SE9301490D0; SE9301490L

Description

Method of operating a sprinkler installation and a device for executing the method

The invention refers to a method for operating a sprinkler installation for fighting fire and which comprises an alarm device, a plurality of spray heads provided with thermal fuse elements, a pump device comprising at least one sprinkler pump which is adapted to discharge, upon a signal from the alarm device, water in a volume and with a pressure which are needed for the function of the sprinkler device, and a tubing (piping) system connecting the the pump device with the spray heads.

With "spray head" is in the present specification and in the annexed claims understood a means for discharging water in the form of jets or fog. With "thermal fuse element" is understood a means which triggers the respective sprinkler head when a predetermined elevated temperature is reached; it is generally a glass bulb which bursts by heat.

The invention refers also to a device for executing the method.

In conventional sprinkler installations for fighting fire, water for extinguishing the fire is discharged from the spray heads in jets, whereto relative large quanti¬ ties of water are needed. The sprinkler pumps are driven by an elecric motor, and in a known sprinkler system they are driven so, that the tubing system is constantly filled with with low pressure water (having the pressure of the water in the mains, i.e. 4 to 5 bars, which thus constitutes the stand¬ by pressure of the sprinkler installation) .

For compensation of little leakages comprises the pump device besides of the sprinkler pump a pressure stabil¬ izing pump having only a small capacity (discharging a smaller flow than what is necessary for a single spray head) and delivering a maximum pressure (e.g. 6 to 7 bars) which lays only slightly above the stand-by pressure. The pressure stabili ing pump is driven by a pressostat and is constantly switched on. The sprinkler pump and the tubing system with its pipe flanges etc. are designed for a maximum pressure in the order of 10 bars, which is the conventional operational pressure of the system.

When one or more of the spray heads are triggerd after the respective glass bulb has bursted, the pressure in the tubing system decreases rapidly and the sprinkler pump is automatically started to provide the whole sprinkler installation with water for extinguishing the fire. In this connection is the pressure (10 bars) of the water delivered to the spray heads of smaller importance than what a sufficient flow is, because from each spray head are 60 to 180 litres ejected each minute. The tubing system must have a suf¬ ficiently large diameter for such a flow.

The starting up of the sprinkler pump is however somewhat delayed (e.g. appr. 40 to 50 seconds) , which is obviously a serious drawback. The reason for the delay is that the alarm valve, which operates as a check valve between the holder of the sprinkler and the sprinkler pump, needs appr. 40 second to lift, i.e. to give alarm, and then it takes appr. 10 seconds for the automat..cs (Y-D start) to generate full pressure in the pump.

It is an object of the present invention to provide a method and a device in which the pressure stabilizing pump may be omitted, the tubing system may have a smaller diameter, and the delay at the start does not occur.

These objects are achieved according to the invention in a way which is evident from the enclosed claims, by "high pressure pump" being there understood a pump which can deliver a pressure 10 to 2ύ times higher than what the pressure in a conventional sprinkler pump is, i.e. a pressure in the order of magnitude of 100 to 200 bars.

According to the invention, the high pressure pump with regulated rotation speed delivers only the volume of water which is instantly consumed, i.e. discharged by the spray heads, without the necessity of ever to return any quantity of water to the pump. This is different from pumps with unvariable capacity, in which discharged water which is not consumed is recycled ("by-passed) to the pump, with the result that spill heat is generated.

Upon the start of a high pressure pump appears, however, the disadvantage that in a tubing system which is not, or not completely, filled with water, the air comprised therein is compressed so that violent pressure strokes ("hammer stroke effect") come up, which may cause that the whole tubing system is shaken down after a time. By the tubing system being according to the present invention constantly kept free of air and filled with water with stand-by pressure, e.g. 10 bars, no pressure strokes occur when the pressure is increased to the operational value of between 100 and 200 bars.

Thus, water with the high operational value is present in the spray heads as soon as an alarm has been given, but it is held back by the glass bulbs, and sprinkling commences only after these bulbs have bursted due to the effect of heat.

This means that no sprinkling occurs when a false alarm has been given, i.e. when an alarm signal (triggered e.g. by smoke) is not followed by development of heat. The operational pressure, i.e. the increased rotation speed, can be put back manuctlly.

Preferably one takes (programs) further the disposition that the rotation spped of the pump, and thus also the water pressure, is increased to the higher values even when the alarm device of some reason becomes unoperational, because this possibly may be caused by a circumstance which may involve the risk of fire. Sprinkling begins even in such a case only if and when the glass bulbs have burst hy heat.

When in the fire centre a signal is received which indicates that some detector has been removed or is out of order, a signal is sent to the control member of the pump ("the control box") to increase the pressure to the operational value. If the connection (line) between the fire centre and the control member of the pump is severed, a signal is also sent to the control member of the pump by an activated relay in the control box being dropped which is fed externally (i.e. not from the source of current feeding the alarm system) . This occurs even at a normal fire alarm. The circuit is fed by the relay voltage.

Should all these signals be absent, pressure is increased to the operatoional value as soon as a glass bulb bursted, i.e. as soon as a flow comes about, which is sensed by a flow sensor in the out-line of the pump, or is measured on the armature voltage of the motor of the pump.

In a preferred embodiment of the invention, the pump device comprises besides of the sprinkler pump, which operates as a mother pump, one or several (e.g. 8) slave or additional pumps which are drivable with constant speed and which, once started, operate at full effect. The purpose of the additional pumps is to increase the water capacity while the mother pump, reduced e.g. to 25% of its performance, continues as before to control the pressure and the flow until the additional pump or pumps no longer are needed. Then the additional pump or pumps are stopped and only the mother pump continues to operate, if needed even at its full capacity.

While it is in principle possible to use as the high pressure pump with variable speed also an aggregate consisting of a motor rotating with unvariable speed plus a separate .speed controller, in a preferred embodiment of the invent.i m the high pressure pump is embodied by a pump driven by a thyristor-controlled D.C.-motor.

The invention will now be explained more in detail with the aid of an exemplary embodiment according to the enclosed drawing which is a diagram in which water conduits are shown by double lines and electric connections by single lines.

A high pressure pump 1 is driven by a thyristor- controlled D.C.-motor 20 with variable speed and is fed from a mains water line 18 by way of a water filter 6, a (pressure ■free) break tank 7 and in-line 18a.

Through an out-line 17 which is embodied by a high pressure conduit, and in which a flow sensor 3 sensing the flow, and a transducer 4, sensing the pressure, are arranged, is pump 1 connected to a plurality of fog spray heads 13 which are provided with heat sensitive triggers known per se, such as glass bulbs. The pressure in the out-line 17 is indicated on a display instrument 5. In the line 17, more correctly in a branching 17 'thereof, leading to the fog spray heads 13, is a closing valve 11 and a run-off valve 12 for the fog sprinkling water provided.

Besides of the pump 1, there as a plurality (in practice e.g. 8) additional pumps 2 provided which are driven by A.C.motors 21 and which through a line 18b are fed with water from the main line 18, more correctly from the break tank 7. The out-lines of the additional pumps 17a are connected to the line 17 via the main or mother pump 1.

The electrical motors 1 nad 2 are through electric lines 20a and 21a fed with current from a central control means (control box) 8 to which feeder current is brought via a line 15. The flow and pressure values, sensed by the sensors 3 and 4, are fed into the control box 8 through lines 3a and 4a, and via a line 14a is information about the water level in the reak tank 7, in which a level sensor 14 is provided to this purpose, fed into the box 8. In the control box 8 are further provided, among other things, two rotary potentiome¬ ters 4", 4" for setting the two pressure values (stand-by pressur and operational pressure) , and a thyristor bridge 20b for controlling the motor 20.

A fire alarm centre 9 is by an alarm line 16 connected with (smoke or heat sensitive) fire detectors (not shown) which are distributed in the space which shall be monitored, and by a line 9a is the fire centre 9 connected to the control box 8.

The closing valve 11 is by a line 11a connected to a programable logical system (PLS) 10 for the control of valves, which system is in its turn via a line 10a connected the fire alarm centre 9.

PLS can be programmed so as to upon a fire open a closed valve (e.g. valve 11) in the section in which the valve is located, or a closed valve which controls the flow to a large space (e.g, a restaurant) where everthing shall be fog- sprinkled at the same time (so called "deluge") .

When the firemen have arrived, they take care of the extinguishing operations with their own means and sprinkling is no longer either needed or desired. The valve is then closed either manually or by the PLS 10 being programmed after some time (e.g. 4 minutes) again to close the previously opened valve. When the valve is closed, the flow decreases and the additional pump or pumps are no longer needed.

The installation operates in the following manner. The high pressure pump 1 is continously driven by the motor 20 with a speed which results in the line 17 in pressure of e.g. 10 bars, the stand-by pressure of the sprinkler installation, and the valve 11 is open. The motors 21 and the pumps 2 are at rest.

When a fire alarm arrives through the line 16, it is received by an interface in the control box 8 and the speed of the mother pump is so controlled by the thyristor bridge 20b that the pressure in the tubing system increases to and is kept at the predetermined operational pressure value, e.g. 100 bars, the flow being allowed to vary.

This pressure spreads swiftly to the fog spray heads 13, which, however, do not begin to work before their thermofuse elements have been affected, i.e. the glass bulbs have bursted. Consequently, high pressure is already "on pla¬ ce" in the fog spray heads when this occurs.

When the pressure sensor 3 continuously "reports" to the control box 8 that the pressure in the line 17 has a lower value than the predetermined operational value which is set on one of the rotary potentiometers 4b¹, 4b" (e.g. 100 bars) , the speed of the mother pump 1 is increased till the operational pressure is attained or, if the mother pump has attained a predetermined part of its maximum performance (e.g. 75% thereof) , a signal is generated in the control box 8 that a first additional pump 2 shall start, and at the seme time a signal* is given to the motor 20 to reduced the rotation speed to a predetermined lower value (corresponding e.g. to 25% of the maximum performance of the mother pump 1) .

If the mother pump 1 with the first additional pump 2 running again reaches said predetermined performance value (e.g. 75%) , additional pump number two is started, and at the same time a signal is given to mother pump 1 to attain again the predetermined second reduced value (e.g. 25% of the maximum performance) . This procedure is repeated as often as necessary, until possibly all additional pumps are running. The additional pump are thus consecutively started one after the other, the second after the mother pump after the the start of the first one again has reached the predetermined part of its maximim capacity, etc., etc.

The mother pump regulates now the rotation speed of the whole system so that correct pressure and flow is achieved, and to the spray heads 13 flows water as well from the mother pump 1 through the line 17, as from the additional pumps 2.

If, because of some reason, the fire alarm from the detectors may not be coupled to the mother pump 1, this pump is activated when, and by the fact that the thermal fuse element (glass tube) in any of the spray heads is destroyed. The first water which then comes out from the spray head has only stand-by pressure, i.e. 10 bars for instance, but as soon as a fl >w comes about in the line 17 and is sensed by the flow sensor '. , a signal is generated to increase the rotation speed of the motor 20 so that the pressure increases to its operational value, e.g. 100 bars.

The purpose of the at least one additional pump 2 which goes for full after having ben started is to increase the water capacity. The flow and the pressure in the line 17 continue to be regulated, as before, by the mother pump 1 (reduced to 25% performance) until the additional pump or pumps 2 r.o longer are needed, as mentioned before. Then it or they are stopped and only the mother pump 1 operates.

The advantage of using one or more (e.g. 8) non speed- regulated, D.C.-driven and direct-started additional pumps w.iich are connected to the speed regulated mother pump is the low price of available pump capacity and a simple and non expensive storage of replacement parts.

The additional pump or pumps may also be used as spare pumps and be individually started, thus increasing the fire security.

Claims

1. A method of operating a sprinkler installation fo fire fighting, comprising an alarm device, a plurality of spra heads provided with thermal fuse elements, a pump device control led by a control member, and a tubing system connecting the pum device with the spray heads, the pump device comprising at leas one sprinkler pump driven by an electric motor and arranged t maintain, in the stand-by condition, the tubing system fille with water having a lower, stand-by, pressure and, when an alar signal, generated in the alarm device, appears, to feed into th tubing system water in a quantity necessary for the extinguishin function of the spray heads and with the necessary higher opera ing pressure, characterized in that the sprinkler pump in th pump devise is embodied by a high pressure pump with variable ro tation speed, so that by variation of the rotation speed the vo lume and/or the pressure of the water fed into the tubing syste is variated, the pump device being normally driven at a lowe first speed so that the pump device, when the stand-by pressur in the tubing system decreases, as a pressure stabilizing pum maintains said pressure at its preselected value, and upon appea rence of said alarm signal is driven at a higher rotation spee so as to create in the tubing system the flow for the extingui shing function of the sprinkler installation and/or the highe operational pressure, e.g. 100 to 200 bars which is necessary t this purpose.

2. The method of claim 1, characterized in that th spray heads are made fully operational immediately after havin been triggered due to the fact that the pressure in the tubin system is by said speed increase augmented to the operationa value already before the thermal fuse elements have bursted.

3. The method of claim 2 or 3, characterized in that flow and/or pressure sensor, connected to the control member o the pump device, is provided in the tubing system, and that th pump device further comprises at least one additional pump whic is driven at unvariable rotation speed and which is automaticall started when the capacity of the mother pump, sensed by a flo and/or pressure sensor, is utilized to a predetermined part o its maximum value, the capacity of the mother pump being at the same time reduced by decreasing the rotation speed to a smaller part of its maximum value.

4. The method of claim 4, characterized by the fact that when a plurality of additional pumps is present, they are started one after the other so that the second one is started when the mother pump again has reached the predetermined part of its maximum capacity after the first additional pump had been started, etc. etc.

5. The method of claim 3 or 4, characterized in that the additional pump or pumps are stopped when they no longer are needed due to decreased flow demand, the mother pump continuing to operate alone, possibly at maximum capacity.

6. A method according to one or more of the preceding claims, characterized in that the stand-by pressure is in the order of magnitude of 10 bars, the operational pressure is in the order of magnitude of 100 to 200 bar, and the possibly applicable two predetermined parts of the maximum capacity of the mother pump are in the order of magnitude of 75% and 25% respectively.

7. A device for operating, according to the method of one or more of the preceding claims, a sprinkler installation for fighting fire, comprising an alarm device, a plurality of spray heads (13) provided with thermal fuse elements, a pump device controlled by a control member (8), and a tubing system (17, 17') connecting the pump device with the spray heads, the pump device comprising at least one sprinkler pump (1) which is driven by an electric motor and is arranged to constantly maintain the tubing system filled with water with a lower, stand-by, pressure and, when an in the alarm device generated alarm signal comes up, to feed into the tubing system water with a higher, operational pressure, necessary for the extinguishing function of the spray heads, in a quantity necessary for the said extinguishing func¬ tion, characterized in that in the pump system is as the sprinkler pump installed a high pressure pump with variable rotation speed, and that the control member is arranged to maintain, in the stand-by condi¬ tion, this speed at a setting to a lower value corresponding to a preselected lower value of the stand-by pressure of the water which is being fed out, and upon reception of an alarm signal or start signal to increase the rotation speed to a second, higher value corresponding to a preselected second, higher pressure value of the water which is being fed out.

8. The device of claim 7, characterized in that the pump device further comprises at least one slave pump or addi¬ tional pump (2) which is drivable with unvariable rotation speed and which has a lower capacity, and that the control member is adapted to start the additional pump or pumps when the capacity of the sprinkler pump, operating as a mother pump, has reached a predetermined part of its maximum value.

9. The device of claim 8, characterized by the control member being adapted to decrease the performance of the mother pump to a predetermined smaller part of its maximum value, and to stop the additional pump or pumps when they no longer are needed.

10. The device of claims 8 and 9, characterized by ro¬ tary potentiometers (4b⁷, 4b") for setting the said two parts of the maximum capacity of the mother pump.

11. The device of claim 8 or 9, characterized by the mother pump being driven by a D.C. motor (20) with variable rota¬ tion speed, and the possibly present additional pump(s) being driven by an A.C. motor (21) .

12. The device of one or more of the claims 7 to 11, characterized by the capacity of the additional pump or pumps being in the order of magnitude of half of the mother pump's capacity.

13. The device of one or more of the claims 7 to 12, characterized by a pressure sensor (4) and/or a flow sensor (3) being provided in the tubing system, the output signals of which are fed into the control member.

14. The device of one or more of the claims 7 to 13, characterized by a display instrument (5) for indicating the pressure in the water which leaves the pump device.

15. The device of one or more of the claims 7 to 14, characterized by a sensor adapted to set the value of the opera¬ tional pressure when the detector and/or alarm system is non operative.

16. The device of one or more of the claims 7 to 15, characterized by the spray heads being fog spay heads.