GB2375301A

GB2375301A - Fire control/extinguishment system

Info

Publication number: GB2375301A
Application number: GB0110622A
Authority: GB
Inventors: Gerald William Nolan; Robert Jeffrey Guy; Huw David Davies
Original assignee: Atlas Fire Engineering Ltd
Current assignee: Atlas Fire Engineering Ltd
Priority date: 2001-05-01
Filing date: 2001-05-01
Publication date: 2002-11-13
Anticipated expiration: 2021-05-01
Also published as: GB0110622D0; GB2375301B

Abstract

A fire control/extinguishment system connected to water main supply 3 has water outlet devices (such as sprinklers) and a primary pump flowline 2 for delivering water from the main supply to the outlet devices. The primary pump flowline includes a variable output primary system pump 5 and pressure sensors downstream 7,8 and upstream 6 of the pump such that the primary system pump output is tailored to operate in a predetermined pumping output regime having regard to an upper threshold limit for the downstream pressure sensor and a lower threshold limit for the upstream pressure sensor. The system maximises the supply available from the mains water supply by boosting pressure. A pressure make up jockey pump 16 is arranged in an anti-siphonage bypass 15 to maintain the water pressure at a predetermined pressure above mains pressure when the pump 5 is in a standby mode.

Description

Fire Control/Extinguishment System The present invention relates to a fire control/extinguishment system, such as, for example, a fire sprinkler or deluge system.

Fire control/extinguishment systems (such as sprinkler or deluge systems) are commonly used in dousing fires in buildings and rely on water outlet devices (such as sprinkler devices) having elements which fuse, fracture or otherwise operate when a fire breaks out permitting water to be pumped via the output device. Problems exist with such systems in that mains supply water is becoming commonly held at relatively low pressure in order to reduce wastage from leakage out of the mains pipe network. To counter this problem, large unsightly water storage tanks are frequently employed where fire control/extinguishment systems are necessary in order to store a suitably large quantity of water for use should the system be brought into action. The large storage tanks and associated pumping apparatus take up extensive space and such systems are therefore unsuitable for use in certain circumstances (such as where existing buildings are retrofitted with sprinkler systems).

Other solutions have been proposed. For example GB-A- 2280368 describes a sprinkler system in which a more moderate sized storage tank in used fed from the mains supply. The footprint of the arrangement shown in 2280368 is however relatively large (by virtue of the fact that a tank and multiple pumps are employed) and therefore is not

particularly suited for use in all circumstances.

An improved system has now been devised.

According to a first aspect, the present invention provides a fire control/extinguishment system including: a connection to water main supply ; one or more water outlet devices; and, a primary pump flowline arrangement for delivering water from the main supply to the one or more water outlet devices, the primary pump flowline arrangement including ; a variable output primary system pump; a pressure sensor downstream of the pump; a pressure sensor upstream of the pump; Wherein the primary system pump output is tailored to operate in a predetermined pumping output regime having regard to an upper threshold limit for the downstream pressure sensor and a lower threshold limit for the upstream pressure sensor.

In one embodiment, the water outlet devices may comprise sprinkler devices.

The system preferably includes a controller (which may be integrated with the pump) for controlling the pump output.

The downstream pressure sensor and upstream pressure sensor are preferably connected to the controller, the controller varying the output of the pump dependent upon the pressure sensed at the downstream and upstream pressure sensors.

The upper threshold limit for the downstream pressure sensor is preferably arranged to be set at a variable range of values. The lower threshold limit for the upstream pressure sensor is preferably arranged to be set a plurality of variable values. The lower threshold limit for the upstream pressure sensor is preferably always set at positive pressure (i. e. above vacuum pressure).

The system preferably further includes a sensor downstream of the pump arranged to sense a drop in pressure in the flow line downstream of the pump, the relevant sensor preferably being arranged to start up the pump operation upon sensing the flowline pressure drop downstream of the pump.

The controller preferably acts to monitor the pressures sensed by the upstream and downstream pressure sensors and tailor the pump driving motor speed accordingly.

Providing the lower threshold limit for the upstream pressure sensor is met or exceeded, the controller preferably ensures that the pump output is sufficient to induce pressure downstream of the pump at a preset output

level, preferably a maximum level (which may be the upper threshold limit of the downstream pressure sensor or a level set below that level).

Desirably, the controller operates such that, providing the lower threshold limit for the upstream pressure sensor is met or exceeded, the drive motor of the pump reaches maximum over a relatively short pressure increase, preferably over a minor proportion of the overall pump output pressure range. Preferably the pump motor reaches maximum speed by the time the pressure has risen to five to twenty percent of the upper threshold limit pressure for the downstream pressure sensor. For example, where the lower threshold limit for the upstream pressure sensor is 0.2 bar and the upper threshold limit for the downstream pressure sensor is 10 bar, it is preferred that the controller operates the motor speed to reach a maximum at approximately 0.7-1 bar.

It is preferred that the controller operates the system such that when the pressure sensed at the upstream pressure sensor reaches the lower threshold limit, the pump output ceases, the pump output recommencing when the pressure level sensed by the upstream pressure sensor again reaches the threshold limit. The system is preferably provided with a manual re-set such that only manual interference can switch the pump off finally.

Beneficially the system includes valve means upstream of the upstream pressure sensor, the valve means preferably including a dual valve arrangement and/or at least one non-

return valve.

Beneficially the system includes valve means downstream of the pump, the valve means preferably including a pump discharge non-return valve.

A bypass flowline may be provided directly from the mains supply to the primary flowline flowise proximate the one or more water output devices, to provide full water supply when the primary system flowline components require testing, replacement and/or repair. The bypass flowline will typically include stop valves and non-return valves.

It is preferred that the system includes a bypass flowline including a secondary pump which may be used to pump water from the mains supply to a position downstream of the primary system pump. Operation of the secondary pump is used to pump water into the main flowline to ensure that the pressure (when the primary system pump is in a stationary (standby) mode) in the flowline downstream of the primary system pump is kept at a predetermined level with respect to the pressure of the mains supply (preferably at a higher pressure with respect to the pressure of the mains supply). The primary system pump is held in a stationary (standby) mode at all times when not operationally pumping, other than when the system is manually de-activated following a fire control/extinguishment event.

According to a further aspect, the invention therefore provides a fire control/extinguishment system including:

a connection to water mains supply; one or more water outlet devices; a main system pump arrangement for delivering water from the mains supply to the one or more water outlet devices; and pressure make-up pump means arranged to maintain the water pressure in a flowline comprising the main system pump at a predetermined level above mains pressure when the main system pump is in stationary (standby) mode.

The invention will now be further described in a specific embodiment by way of example only and with reference to the accompany drawing which is a schematic diagram of a system in accordance with the invention.

Referring to the drawing there is shown a sprinkler system 1 comprising a primary system flowline 2 extending from a connection 3 to the town's main water supply to an output 4 which is connected to a pipe network supplying a number of sprinklers (not shown). The primary system flowline 2 includes a variable motor speed pump 5, an upstream pressure sensor 6 and two downstream pressure sensors 7, 8.

A controller 9 is provided for controlling the speed of the motorised pump 5 and receiving pressure sensor inputs from sensors 6,7, 8. In the arrangement shown, the controller 9 is separate from pump 5, however it could be provided in a common unit with pump 5 (or be provided integrally

therewith).

Upstream pressure sensor 6 is provided downstream of a pump inlet stop valve 10 and a dual valve arrangement 11 which includes a non-return valve lla inhibiting water passing from primary flowline 2 back into the mains water supply.

Pressure sensor 6 senses the pressure upstream of pump 5 (i. e. the pressure of water incoming from the town's mains supply) and feeds the output to controller 9. Pressure sensors 7 and 8 sense pressure in the primary flowline 2 downstream of pump 5 and perform different functions as will be explained hereinafter. It is feasible that sensors 7 and 8 can be replaced with a single sensor giving an input to controller 9. A pump discharge non-return valve 12 and pump discharge stop valve 13 are provided in primary flowline 2.

In normal circumstances where there is no fire and consequently no demand for water supply to the sprinkler heads, the system is maintained in pressurised equilibrium with the pump 5 in stationary (standby) mode. It is beneficial to hold the system in this state with the pipework downstream of valve 12 held slightly elevated (approximately 0.3 bar) relative to the mains water pressure (irrespective of what the mains pressure is).

This results in positive prevention of back flow into the mains supply from the installation pipework. Accordingly an anti-siphonage bypass 15 is provided in which water from the mains water supply may be pumped via jockey pump 16 to a position in the main flowline 2 downstream of pump 5. Should the water mains pressure fall, the pressure in

flowline 2 downstream of valve 11 may be reduced by a suitable outlet valve. Anti-siphonage flowpath 15 includes a pump inlet stop valve 17 dual valve arrangements 18 and 19 and a jockey pump 16 and discharge non-return valve 20.

A pressure sensor 29 controls operation of jockey pump 16.

When the system is activated by a fusible element of one or more respective sprinkler heads melting, demand is put on the system and water in primary flowline 2 flows under pressure to the relevant sprinkler head or heads.

Immediately upon activation of the sprinkler heads, pressure sensor 7 senses a drop in water pressure in primary flowline 2 which causes primary system pump 5 to become activated. Primary system pump 5 is operated by controller 9 such that its motor speed is ramped to rapidly reach maximum speed. Typically the speed of the motor is controlled by controller 9 to reach a maximum speed in a short space of time and over a short range of increasing water pressure.

The system is operated by controller 9 such that when the pressure level at pump upstream sensor 6 falls to a predetermined lower threshold limit (for example 0.2 bar) primary system pump 5 output is suspended. This prevents a vacuum being created in the mains supply pipework which is extremely deleterious to the mains water supply system.

Providing the pressure level sensed at pressure sensor 6 remains above the threshold limit (for example 0.2 bar), pump output is maintained at (or ramped up to) a maximum, also provided that an upper pressure threshold level sensed

at pressure sensor 8 is not exceeded. The upper pressure level may for example be set in the range 7 to 10 bar maximum pressure. The controller 9 operates to optimise the pump output between the lower threshold pressure level sensed by sensor 6 and the upper threshold pressure level sensed at sensor 8. The lower threshold pressure level at the upstream sensor 6 and the upper threshold level of the downstream sensor 8 may be set according to various requirements.

A bypass flowline 25 is included by bypassing the main flowline 2 between the mains connection 3 and the connection to the sprinkler output apparatus (not shown).

Bypass flowline 25 is typically used when components in the mains system flowline 2 require maintenance or repair. The bypass flowline 25 includes an inlet stop valve 26, dual valve arrangement 27 and bypass discharge stop valve 28.

The system in accordance with the invention is designed to maximise the supply available from the mains water supply by boosting mains pressure. In order that the inlet pressure form the mains supply is never permitted to fall to zero pressure, the primary system pump 5 motor speed is controlled extremely accurately and only permitted to pump in situations where the inlet pressure to the pump 5 stays above a minimum pressure threshold which can be very accurately set and varied (for example to 0.2 bar). This ensures that the suction pressure is maintained at a positive pressure at all time thus preventing a vacuum forming. The forming of a vacuum causes severe damage to mains supply and results in air being drawn into the

pipework.

The system typically includes alarm circuits providing warning in the event of the following circumstances: Power Failure Signals problems with the power supply (including Phase failure).

Pump Running Signals that the pump is running.

Water Level Alarm Monitors for a rise in water level in a pump room prior to flooding becoming a threat to the equipment.

Low-Pressure Alarm Monitors under performance of pump duty.

Valve-Set Monitoring All system critical valves would be monitored.

The following alarm circuits may be provided: Sprinkler Operation Signals operation of one or more sprinkler heads.

Low-Pressure Alarm A'low-pressure'alarm to monitor under performance of the incoming water main supply.

Event Logging Device Captures any or all events (i. e. jockey pump operation, primary system pump operation).

Remote Testing A remote automated testing facility for checking the pump performance duties may be provided.

Auto Testing An automatic testing facility permitting either remote testing or

automated testing.

Control for Other Provision can be provided for interEquipment facing with other equipment which may require either starting or stopping.

Air Venting Provision for automatic venting of air from the primary system pump discharge pipe.

Temperature Temperature sensing may be provided for signalling low or high room temperatures (particularly important if there is a possibility of temperatures falling below +4 C).

In the specific exemplary embodiment disclosed, the invention has been described primarily with respect to a fire control/extinguishment sprinkler system. It will however be readily appreciated that the invention is equally applicable to other forms of fire control/extinguishment systems utilising other water outlet devices.

Claims

CLAIMS 1. A fire control/extinguishment system including: a connection to water main supply; one or more water outlet devices; and, a primary pump flowline arrangement for delivering water from the main supply to the one or more water outlet devices, the primary pump flowline arrangement including; a variable output primary system pump; a pressure sensor downstream of the pump; a pressure sensor upstream of the pump; Wherein the primary system pump output is tailored to operate in a predetermined pumping output regime having regard to an upper threshold limit for the downstream pressure sensor and a lower threshold limit for the upstream pressure sensor.
2. A system according to claim 1, wherein the water outlet devices comprise sprinkler devices.

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3. A system according to claim 1 or claim 2, wherein the system includes a controller for controlling the pump output.
4. A system according to claim 3, wherein the controller and pump comprise an integrated unit.
5. A system according to claim 3 or claim 4, wherein the downstream pressure sensor and upstream pressure sensor are connected to the controller, the controller varying the output of the pump dependent upon the pressure sensed at the downstream and upstream pressure sensors.
6. A system according to any preceding claim, wherein the upper threshold limit for the downstream pressure sensor is arranged to be set at a range of values.
7. A system according to any preceding claim, wherein the lower threshold limit for the upstream pressure sensor is preferably arranged to be set a range of values.
8. A system according to any preceding claim, wherein the lower threshold limit for the upstream pressure sensor is arranged to be assuredly set at positive pressure (i. e. above vacuum pressure).
9. A system according to any preceding claim, further including a sensor downstream of the pump arranged to sense a drop in pressure in the flow line downstream of the pump.

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10. A system according to claim 9, wherein the sensor is arranged to start up the pump operation upon sensing the flowline pressure drop downstream of the pump.
11. A system according to any of claims 3 to 10, wherein the controller acts to monitor the pressures sensed by the upstream and downstream pressure sensors and tailor the pump driving motor speed accordingly.
12. A system according to any of claims 3 to 11, wherein providing the lower threshold limit for the upstream pressure sensor is met or exceeded, the controller preferably ensures that the pump output is sufficient to induce pressure downstream of the pump at a preset output level.
13. A system according to claim 12, wherein the present output pressure level is a maximum level (which may be the upper threshold limit of the downstream pressure sensor or a level set below that level).
14. A system according to any preceding claim including a controller for controlling the pump output, wherein the controller operates such that, providing the lower threshold limit for the upstream pressure sensor is met or exceeded, the drive motor of the pump reaches maximum over a relatively short pressure increase.
15. A system according to claim 14, wherein the controller operates such that, providing the lower threshold

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limit for the upstream pressure sensor is met or exceeded, the drive motor of the pump reaches maximum over a minor proportion of the overall pump output pressure range.
16. A system according to claim 14 or claim 15, wherein the pump motor reaches maximum speed by the time the pressure has risen to five to twenty percent of the upper threshold limit pressure for the downstream pressure sensor.
17. A system according to any preceding claim including a controller for controlling the pump output, wherein the controller operates such that when the pressure sensed at the upstream pressure sensor reaches the lower threshold limit, the pump output ceases.
18. A system according to claim 17, wherein the system is operated such that the pump output recommences when the pressure level sensed by the upstream pressure sensor rises to the threshold limit.
19. A system according to any preceding claim, including a manual re-set such that only manual interference can switch the pump off.
20. A system according to any preceding claim including a bypass flowline extending from the mains supply to the primary flowline, connecting flowise proximate the one or more water output devices.

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21. A system according to claim 20, wherein the bypass flowline includes a secondary pump arranged to pump water from the mains supply to a position downstream of the primary system pump.
22. A system according to claim 21, wherein the secondary pump operable to pump water into the main flowline to ensure that the pressure (when the primary system pump is in a stationary (standby) mode) in the flowline downstream of the primary system pump is kept at a predetermined level with respect to the pressure of the mains supply.
23. A system according to claim 22, wherein the pressure in the system downstream of the primary system pump is maintained at a higher pressure with respect to the mains supply pressure.
24. A system according to any preceding claim, wherein the primary system pump is held in a stationary (standby) mode at all times when not operationally pumping, other than when the system is manually de-activated following a fire control/extinguishment event.
25. A fire control/extinguishment system including: a connection to water mains supply; one or more water outlet devices;

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a main system pump arrangement for delivering water from the mains supply to the one or more water outlet devices ; and pressure make-up pump means arranged to maintain the water pressure in a flowline comprising the main system pump at a predetermined level above mains pressure when the main system pump is in stationary (standby) mode.
26. A system substantially as described herein with reference to the accompany drawings.