GB2344762A

GB2344762A - Fire sprinkler system

Info

Publication number: GB2344762A
Application number: GB9827434A
Authority: GB
Inventors: Bernard Cain
Original assignee: Project Fire Engineers Ltd
Current assignee: Project Fire Engineers Ltd
Priority date: 1998-12-14
Filing date: 1998-12-14
Publication date: 2000-06-21
Also published as: EP1010441A3; EP1010441A2; GB9827434D0

Abstract

The system comprises at least one sprinkler; break tank for receiving water from a mains water supply; pump means for supplying water from said break tank means to said at least one sprinkler; means for providing water to said at least one sprinkler from said mains water supply other than by way of said break tank means, and including check valve means for preventing reverse flow of water to said mains water supply; and pressure detection means operable to detect pressure of water supplied to the or one or more of said at least one sprinkler, and operable to cause said pump means to be operated when said pressure is below a predetermined value. System alleviates pressure drop in the mains water supply and prevents back flow of water from the system into the water mains.

Description

1 1 1 1 1 1 2344762 Title: FIRE SPRINKLER SYSTEMS

Description of Invention

This invention relates to fire sprinkler systems.

Fire sprinkler systems are well known for fire protection. A typical sprinkler system includes a number of suitably positioned sprinklers of a type which is caused to commence operation when an abnormally high temperature is detected. Typically such detection is effected by melting of a fusible element in each sprinkler. The system further comprises the necessary pipework for supplying water to the sprinklers.

It is usual to supply a sprinkler system with water from a water main, in which case it is essential that the main should be able to supply water to the system at sufficient pressure and flow rate to supply the sprinklers which have been brought into operation. It will be appreciated that for many fires not all the sprinklers of a system will be brought into operation, as the initial operation of one or more sprinklers will prevent spread of the fire beyond the area protected thereby.

One problem with the supply of water from the water mains to sprinkler systems is that water supply authorities are endeavouring to reduce mains water pressure to the minimum value which they are legally obliged to provide. This is done in order to reduce waste of water by leakage from the water mains. Whilst the ability of most mains is adequate to meet the flow rate requirements of sprinkler systems, in many cases the pressure will no longer be sufficient for satisfactory operation, and this is particularly a problem in respect of the operation of sprinklers on the upper storeys of multi-storey buildings. The standard method of meeting the requirements of a sprinkler system where mains pressure is low is to install a relatively large water storage tank and pumps to 2 supply the sprinklers from such tank. A further method of meeting the requirements is disclosed in our British patent GB-2280368-B, which utilises a break tank for receiving water from the mains and from which pump means supplies water to the sprinkler(s). In this method, the break tank may be of relatively small capacity, although the system as a whole is relatively complex.

Another requirement which has to be borne in mind in the designing of fire sprinkler systems is that any back-flow of water into the mains from the sprinkler system must not occur. In a system such as disclosed in our patent aforesaid, having a break tank, the presence of the break tank ensures that this requirement is met.

It is broadly the object of the present invention to provide an improved sprinkler system which enables any problem of inadequate mains water pressure to be overcome, whilst preventing the possibility of back flow of water from the system into the mains.

According to one aspect of the present invention, we provide a fire sprinkler system comprising:

at least one sprinkler; break tank means, for receiving water from a mains water supply; pump means for supplying water from said break tank means to said at least one sprinkler; means for providing water to said at least one sprinkler from said mains water supply other than by way of said break tank means, and including check valve means for preventing reverse flow of water to said mains water supply; and pressure detection means operable to detect pressure of water supplied to the or one or more of said at least one sprinkler, and operable to cause said pump means to be operated when said pressure is below a predetermined value.

In a system according to the invention, the means for supplying water to the sprinkler(s) other than by way of the break tank means, which means may 3 be a direct connection between a mains supply pipe and a pipe leading to the sprinkler(s), provides for the supply of water to the sprinkler(s) when the water main is capable of delivering sufficient pressure at a flow rate suitable for satisfactory operation of the number of sprinklers in use. If the pressure falls below the predetermined value, however, for example if a fire is of a size such that a large number of sprinklers are brought into operation, or if mains water pressure is low so that a lesser number of sprinklers will not perform satisfactorily, then the pump means is brought into operation and the sprinklers are supplied by way of the break tank. In this latter condition the pump means will deliver water to the sprinklers under a pressure greater than that available from the water mains, but the check valve means prevents reverse flow of water back into the mains.

Since, in a sprinkler installation including one or more sprinklers at a high level, e.g. on an upper storey or storeys of a multi-storey building, as well as one or more sprinklers at a lower level, it is going to be in respect of the high level sprinkler(s) that low mains water pressure is a problem, the pressure detection means is preferably provided at a high level in the system, and further preferably at the level of one or more highest sprinklers of the system.

A sprinkler system in accordance with the invention may also be a system as disclosed in our UK patent aforesaid. The invention is also, however, applicable to simpler sprinkler systems as described hereafter.

The invention will now be described by way of example with reference to the accompanying drawings, of which:- Figure 1 shows diagrammatically afirst embodiment of sprinkler system according to the invention, which is a modification of that described in our patent GB-2280368-B; Figure 2 shows diagrammatically a funher embodiment of sprinkler system in accordance with the invention.

4 Referring firstly to Figure 1 of the drawings, this shows a sprinkler system as described in our British patent aforesaid, modified in accordance with the present invention. For a further description of all the components and the method of operation of the sprinkler system, reference should be made to the patent GB-2280368-B; only parts of it relevant in the context of the present invention are described herein.

In Figure 1, a water main bringing water from a water supply authority is indicated at 50, a part 51 being branched off the main 50 and containing an isolation valve 1 followed by a non-return valve 2. The pipe 52 connects to a pipe 54 which leads by way of valves and other devices to a break tank 8. Water can be withdrawn from break tank 8 by pipes 55, 56, 57 leading to booster pumps 11, 12, 13 and thence to a manifold 58. From manifold 58 a pipe 60 leads by way of a valve 19 to an outlet 61 connected to pipework leading to one or more sprinklers. There are pressure-responsive electrical switches 20, 21, 22 by which the operation of pumps 11 to 13 are controlled. Further components shown in Figure 1 are concerned with the testing and other aspects of the operation of the sprinkler system, and will not be described herein.

In accordance with the present invention, a pipe 70 is branched off the pipe 54 and connected to the pipe 60. The pipe 70 incorporates a check valve 71 for preventing reverse flow of water in the pipe 70, in the direction from the pipe 60 back towards the water main 50. Thus water is capable of reaching the outlet 61 and thence the sprinklers other than by way of the break tank 8, and if the main is capable of providing water at a sufficient flow rate and pressure to ensure operation in satisfactory manner of the number of sprinklers which might be brought into operation, the pumps 11 to 13 will not be brought into operation. If the pumps are brought into operation, however, which will establish a pressure in the pipe 60 greater than that in the main 50, the check valve 71 prevents reverse flow in the pipe 70.

Referring now to Figure 2 of the drawings, this shows a somewhat simpler sprinkler system in accordance with the invention. Figure 2 shows, diagrammatically, a pipe 100 which is connected to a water main 101 by way of a stop valve and non-return valve 102, 103 respectively. An isolating valve 104 is provided upstream of a pipe 105 leading to the inlet control valve 106 of a break tank 107. An outlet 108 from the break tank leads by way of a booster pump 109 with associated valves to a pipe 110 which leads to an outlet 111 for connection to pipework of a network of sprinklers. In the pipe 110 there is shown a sprinkler alarm valve 112 which, when water flows in the pipe 110 due to the coming into operation of one or more sprinklers, provides for the supply of water to a water- operated gong 113. Branching from the pipe 110 is a pump-proving line 114 incorporating a test valve 115; this leads back to the break tank 107 and enables operation of one or more sprinklers to be simulated to test operation of the pump 109 as required. A pressure detector 116 detects the pressure supplied to the sprinklers by way of the outlet 111, and causes the pump 109 to operate when the pressure falls below a predetermined level.

In accordance with the invention, a connection is provided between the pipe 100 and the pipe 110, enabling water to be delivered to the outlet 111 directly from the mains, i.e. not by way of the break tank 107. The connection incorporates a check valve (non-retum valve) 118. If the mains is capable of maintaining the required pressure at the outlet 111, the pump 109 is not brought into operation and water reaches the outlet 111 leading to the sprinklers directly and not by way of the break tank. When the pump 109 is in operation, in response to falling of the sprinkler pressure below a predetermined value, the check valve 118 prevents reverse flow of water from the pipe 110 back to the water mains.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process

1 1 1.

1 ' 1 1 6 for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof

Claims

7 CLAIMS

1. A fire sprinkler system comprising: at least one sprinkler; break tank means, for receiving water ftom a mains water supply; pump means for supplying water from said break tank means to said at least one sprinkler; means for providing water to said at least one sprinkler from said mains water supply other than by way of said break tank means, and including check valve means for preventing reverse flow of water to said mains water supply; and pressure detection means operable to detect pressure of water supplied to the or one or more of said at least one sprinkler, and operable to cause said pump means to be operated when said pressure is below a predetermined value.

2. A fire sprinkler system according to Claim, wherein means for supplying 0 water to the sprinkler(s) other than by way of the break tank means comprises a connecting pipe between a mains supply pipe and a pipe leading to the sprinkler(s).

3. A fire sprinkler system according to Claim 1 or Claim 2 including one or more sprinklers at a high level and one or more sprinklers at a lower level and wherein said pressure detection means is provided at a high level in the system.

4. A fire sprinkler system according to Claim 3, wherein said pressure 0 detection means is provided at the level of one or more highest sprinklers of the system.

8 5- A system according to any one of the preceding claims, which is as disclosed in GB-2280368-B.

6. A fire sprinkler system substantially as hereinbefore described with reference to the accompanying drawings.

7. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.