EP1702655A1

EP1702655A1 - Improved sprinkler test system

Info

Publication number: EP1702655A1
Application number: EP06251429A
Authority: EP
Inventors: Gary Richard Noble
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-03-17
Filing date: 2006-03-17
Publication date: 2006-09-20
Also published as: GB0505462D0

Abstract

A pump initiation test assembly for a sprinkler system is disclosed in which there are provided at least a pair of pressure sensors provided in the same test section of pipework within said assembly and communicating with the same chamber containing pressurised fluid within said pipework. Each of the pressure sensors has associated therewith at least two switches whose state changes simultaneously and between the same states when the fluid pressure within said chamber becomes less than an adjustable pressure threshold of the sensor. In accordance with the invention, the first switch of each switch pair is wired in series with one another and the pump so that any actuation of either switch automatically causes pump actuation. The second switches of each switch pair associated with each sensor are electrically connected, substantially independently of said first switches, and possibly independently of one another, to display means capable of indicating which of the particular sensors is actuated during a test when the fluid pressure becomes less than said threshold. Ideally, the threshold settings for each sensor are different so that the sensors are necessarily actuated at different pressure levels.

Description

This invention relates to a test system, apparatus and method for sprinkler systems installed in domestic or commercial premises, and more specifically to an improved test device for testing particular critical components of sprinkler systems which are adapted to be actuated in the event of a fire, and yet further specifically to a means of testing such components without causing full-scale actuation of the sprinkler system as a whole.
Automatic sprinkler systems are installed in a wide variety of buildings, either as a result of mandatory compliance with legislation, or as a security measure to prevent property damage and/or fatalities in buildings which can be regarded as fire hazards, or may be maliciously set alight. Such buildings may be commercial, industrial, or, less frequently, domestic, but in any sprinkler system, it is usual for the system to comprise more than a single sprinkler head, usually disposed in the ceilings of the various rooms or areas within a building.
The sprinkler heads in the system are interconnected, usually in parallel configuration by means of pipework which is in turn fed from a system pump which supplies the extinguishing liquid, usually water, to the various sprinkler systems. In addition to a fluid outlet within the sprinkler head, there may additionally be provided some form of sensor or transducer which is capable of recognising or detecting changes in the atmosphere in the particular room in which that particular sprinkler head is disposed. The sensor provided may be capable of detecting the presence of heat, light, smoke or noxious or toxic gases, these being indicators of the presence of a fire.
In a common form of sprinkler system, the sensors are adapted to detect heat or a marked increase in atmosphere temperature. Once any one sensor disposed either integrally within, adjacent, or proximate the sprinkler head, or indeed any sensor anywhere in a particular room but nevertheless in communication with the activation mechanism of the sprinkler system, determines that a fire is present in a particular area, the sprinkler system is caused to be activated as hereinafter described.
The extinguishing fluid within the pipework supplying the sprinkler heads is typically maintained within a predetermined design operating pressure range, commonly in the region of 3-10 Bar, although this is a matter of design dictated at least in part by what is to be protected and where it is located. When the sprinkler system is activated, in general the pressurised extinguishing fluid which is extant in the pipework supplying the sprinkler heads in the system is allowed to flow through the sprinkler head most proximate and thus onto the source of the fire. It is to be mentioned that selective activation of the sprinkler system, wherein pressurised extinguishing fluid is allowed to flow through only certain sprinkler heads disposed in certain areas of a building where the presence of a fire has been detected is achieved usually by means of a breakable seal or cap also provided within the sprinkler head, but as this is beyond the scope of this application, no further description is provided here. In general however, the sensitivity of the sensors provided is such that false alarms are generally avoided and sprinkler systems are activated only when the presence of a fire is certain. It is worth mentioning that although the cost of false activation of a sprinkler system is considerable in terms of damage to floors, carpets, furnishings, documents, electronic equipment, etc., it is nowhere near as considerable as the cost of a building and all its contents becoming an inferno.
In any event, it is important that the fluid pressure within the pipework supplying the sprinkler heads is maintained at the pressure of between 7 and 9 bar because when a fire is detected, and the seal on one or more sprinkler heads is broken, fluid must flow through the sprinkler heads as quickly as possible to extinguish the fire as quickly as possible and thus minimise the extent of the damage caused thereby. This can only be achieved if the fluid in the pipework supplying the sprinkler head is pressurised. In other words, the pressurised fluid needs to flow initially very quickly from the sprinkler head under pressure. Subsequently, pump means drives fluid through the pipework to ensure that the flow continues after the initial burst, and this is also crucial, because any fire is unlikely to be extinguished by the first initial burst of fluid through the sprinkler head.
In most modern sprinkler systems, a jockey pump (as opposed to a main pump) is provided in the system to ensure that the system pressure is maintained. This pump is supplied from a reservoir and is provided with a sensor which monitors the pressure in a particular section of the sprinkler system. Pipework can often develop leaks, and therefore jockey pumps of this type are considered essential. The pump is energised if the pressure drops below a predetermined pressure level by means of a pressure sensitive switch controlling the jockey pump. It is arranged that in the presence of a sufficiently intense or large local heat source, the seal of an adjacent sprinkler head will break, thus reducing the pressure in the system below the predetermined value and energising the jockey pump. More than one sprinkler head may respond in such manner to the heat source.
When only one sprinkler head has been activated in this manner, it may be that the jockey pump itself is sufficient to maintain a supply of liquid thereto at a sufficient pressure. Alternatively, it is known to provide additional main pumps which are energised successively as the sensed pressure falls below a corresponding sequence of reduced pressure levels, so as to maintain the flow of liquid to the sprinkler heads.
As part of existing UK and European Legislation, it is necessary to conduct testing of the pumps supplying sprinkler systems, and more specifically to conduct tests to ensure that the pump initiation mechanism is functioning correctly. Obviously, it is impossible to conduct safety testing of sprinkler systems in general due to the damage caused when such are properly activated, and therefore a means has been devised whereby instead of testing the actual functioning of the pump itself, the mechanism by which that pump is caused to be actuated is tested.
In this regard, applicant's earlier granted UK Patent GB2347721 provides a good description of the state of the prior art.
In general, sprinkler systems do not simply have a single pump, but an array of pumps which are provided in case one or other fails in a live fire event (resulting in catastrophic building and contents loss).
A schematic layout of a typical installation which provides for the testing of three separate pump initiation assemblies 10 is shown in Figure 1. A pump initiation test assembly 10 of the layout of Figure 1 is illustrated in Figure 2 and more schematically in Figure 3 for ease of understanding.
The installation illustrated in Figure 1 includes a jockey pump 22, and two further pumps 22a and 22b. The inlet 23 of each pump is coupled by pipework 24 to a common reservoir or other source of sprinkler liquid, and the pump outlets 25 are coupled by pipework 26 to a sprinkler array. Each pump is controlled by a respective electrical unit 27 including a starter, each unit being coupled to receive the output of a pressure sensitive switch 15 of the respective pump initiation test assembly 10.
The installation is designed and set up so that as the pressure in the sprinkler system falls the jockey pump 22 is initially started, and thereafter pump 22a and 22b in succession. The jockey pump also operates to maintain the pressure in the system when no sprinkler heads are in operation, and it is only when sprinkler heads are operating and the sensed pressure falls to first and second predetermined levels progressively lower than the design working pressure that the pumps 22a and 22b are successively activated.
As shown in Figures 2 and 3, where corresponding components are located in approximately the same position for ease of location, each pump initiation test assembly 10 comprises a central section 11 of piping between a normally open ball valve 12 and a normally closed gate valve 13. A flow restrictor 20 is located between the ball valve 12 and the central section 11. Coupled to the central section 1 1 are a pressure gauge 14 and a pressure sensitive electrical switch 15, for example operated by a diaphragm, piston or another suitable pressure driven actuation mechanism, sensing the pressure in pipework 11, which is thus the effective pressure in the system pipework as the other side of the ball valve 12 is coupled by pipework 16 to the sprinkler installation. The other side of the gate valve 13 is coupled to pipework 19 which is common to all assemblies 10 and which leads to a drain. An optional arm sealed with a plug 20 also couples into the section 11.
In the preferred configuration (as shown in dashed lines in Figure 3) a small bore loop 17 forms a bypass around the ball valve12 and restrictor 20, and includes a one-way valve 18 permitting flow only in the direction of arrow 18a towards pipework 16. While it is preferred to have the loop 17 and valve 18 in each of the assemblies 10, if desired the valve may be omitted from the assembly 10 which controls the jockey pump 22, while retaining the loop 17.
To test an initiation assembly 10, the operator closes the ball valve 12 of a selected assembly 10. Since gate valve 13 is normally closed, the pressure in the pipework 11 between the valves 12 and 13 remains at the pressure in the sprinkler installation. The operator now opens the gate valve 13 to allow the pressure to drop slowly until pressure (as shown by gauge 14) drops to a critical level at which the switch is operated, this being detected by any means known. Should the critical level be outside of specification, the switch is adjusted and the assembly re-tested after having been brought up to the pressure in the sprinkler installation once more. Alternatively, but less desirably at least in respect of a final setting, the operator may bring the pressure in the pipework 11 within a specified range by opening and closing the valve 13, thereafter adjusting the switch to its switching point.
In use, if a sprinkler head is breached, for example due to a local heat source, thereby leading to a reduction in pressure in the pipework 16, this reduction in pressure will be rapidly transmitted via the open ball valve 12 to the pressure sensitive switch, thereby leading to starting of the jockey pump 22 and possibly the other pumps 22a, 22b.
Should the operator mistakenly leave the ball valve 12 closed after testing or adjustment of the assembly, the presence of the one-way valve 18 permits liquid flow if the pressure in the sprinkler system or pipework 16 falls, so that the switch and pump will still be operated.
It is worth mentioning at this stage that although in configuration described above, a change in the state of the pressure sensitive switch causes actuation of the jockey pump, but in a commercial system, the switch activation may cause actuation of one or more of the jockey pump, the first duty pump, the second duty pump, and in circumstances where the actuation of at least one pump is critical to prevent catastrophic damage, one or more standby pumps. Obviously, the reader will appreciate that systems incorporating one or more duty pumps and one or more standby pumps, together with at least one jockey pump are very expensive and applicable only to fire extinguishing systems installed in commercially sensitive premises where such might be regarded as "mission critical" to the ongoing activities of the particular organisation or entity owning those premises.
While this pump initiation test assembly is adequate, there has recently been introduced new European Legislation (EN12845) which is to be implemented in UK Law by July 2006 which will force installers of sprinkler systems to provide 2 pressure switches for each pump, whether this be a jockey or boost or main pump, and that furthermore, testing must still be conducted of these new pump initiation test assemblies to determine whether the pump would actuate in the event of a fire, and which of the two pressure sensitive switches would cause actuation of the pump. Both pressure sensitive switches must be tested. It may also be useful (although not mandatory) to provide an indication of the particular pressures at which such switches were constrained to trigger pump actuation.
Of course, this testing is still to be performed without actually causing full scale sprinkler system activation.
In the light of the fact that all sprinkler systems must fail safe, a valve can only be installed inline between the switches if it has a failsafe non-return valve around it in parallel. The implication of this and the forthcoming new legislation is that each pump in a sprinkler system would require not just a separate pressure sensitive switch mounted on the central section 11 as shown in Fig. 2, but a completely separate and additional unit 10 would be required, with all the attendant re-plumbing of existing systems and additional costs to new systems that this would also necessitate.
It is an object of this invention to provide apparatus which can provide electronic verification of a pump initiation test assembly provided with a pair of in-line or series connected pressure sensors. In most cases, such sensors will have associated electric/electronic switch circuitry.
It is a further object of the invention to provide information about the particular status of each of a pair of pressure sensors provided in a pump test initiation assembly, and furthermore provide additional information concerning the status of the switches associated therewith at their last test date, together with details of that test.
It is a further object of the invention to provide a test information display device which can be retrofitted to existing sprinkler systems and their associated pump initiation test assemblies without any significant disruption, or provided together with the above pressure sensors and switches in a new installation. It is worth mentioning that prior to this invention, many systems are now being refitted with whole duplicate pump initiation test facilities as there is no other known means of dual switch verification.
According to the invention there is provided A pump initiation test assembly for a sprinkler system in which there are provided at least a pair of pressure sensors provided in the same test section of pipework within said assembly and communicating with the same chamber containing pressurised fluid within said pipework, said pressure sensors having associated therewith at least two switches whose state changes simultaneously when the fluid pressure within said chamber becomes less than an adjustable pressure threshold of the sensor, a first of said switches of each sensor being electrically connected to at least one pump so as to cause actuation thereof when the fluid pressure within said chamber changes to a value greater or less than said threshold, characterised in that the first switches of each sensor which are electrically connected to said pump are effectively connected in series such that the actuation of either of said switches causes actuation of the pump, and further characterised in that the second switches of each sensor are electrically connected, substantially electrically independently of said first switches, to display means capable of indicating which of the particular sensors is actuated during a test when the fluid pressure becomes less than said threshold.
It is to be pointed out that while the first switches in each pair might be connected within the same overall circuit as the second switches in each pair, the desired effect is that the actuation of either of the first switches in each pair results in a different action to that caused by the actuation of the second switches of each pair of switches associated with said pressure sensors. Thus the result of the first switch actuation is independent to that of the second switch actuation.
Preferably, both switches of both sensors are actuated when the fluid pressure in the chamber falls below said threshold value, and further preferably the threshold values of each sensor are set to different values to ensure that one of the sensors, and thus the particular pair of switches associated with that sensor, is actuated before the other.
In one embodiment, the display means is a simple light suitably mounted and located, preferably proximate the test assembly, and in another embodiment, the apparatus comprises electrical detection means communicating with each pressure sensor and/or associated switches, and memory means associated therewith for storing snapshot information relating to the operation of said sensors, said display means including a display panel on which said snapshot information can be viewed.
As may be understood from the above, the pressure threshold value at which the pressure sensors are configured to be actuated is slightly different so that during any pressure drop test, the apparatus automatically identifies which of the two sensors was actuated by means of a light or through information displayed on the display panel.
Most preferably, both switches associated with each sensor are identical in that their states change in an identical and simultaneous manner when the pressure sensor is actuated. In this manner, during a pressure drop test, the switches of the sensor having the higher of the two threshold values will be actuated first. Such actuation will open the circuit in which the first switches of each of the two sensors are wired, and the pump will start automatically. The display means will indicate that this particular sensor was actuated because the second switch changes state as well as the first, and thus the display means can be illuminated (in the case of a simple light being provided) or updated with relevant information (in the case of a display panel being provided).
As the test is continued, and the fluid pressure in the chamber continues to drop, both the switches of the second sensor having the lower pressure threshold will be actuated. The actuation of the switches will have no effect as regards the fist switch which is electrically connected to the first switch of the first sensor and the pump because the pump has already been started as a result of the above. However, the actuation of said switches is still relevant for the display means, which can be illuminated (or updated) to clearly show that the second sensor was actuated.
This simple indication arrangement precludes the need for extensive re-plumbing of test assemblies, as only suitable pressure sensors have said switches need be provided, provided that the switches of each sensor are correctly electrically connected to provide the function described.
Hence, not only can the criterion of the new European Standard be met safely, test operators can quickly establish the functioning of test assemblies.
In the case of the more comprehensive system incorporating electrical detection means, memory means, and the like, such may be embodied in a PLC (programmable logic controller) having associated display means.
Most preferable the apparatus includes both digital display means and illuminatable display means, most preferably in the form of lights whose illumination or lack thereof indicates that a particular pressure sensitive switch was correctly actuated or did not actuate.
In a yet further preferable configuration, the memory means of the apparatus is further capable of receiving information concerning the day, date, and time of a particular switch actuation, the chamber pressure at which that actuation occurred, and furthermore, it is preferable that such snapshot type information is capable of being stored for a large number of individual, separate pressure drop tests.
Although this seems like an intrinsically simple invention, it is to be pointed out that the new legislation provides only that two pressure sensitive switches must be used, and that some indication of which switch operated, optionally at which pressure, must be provided. In the case where a second switch is simply added onto an existing pump test initiation assembly as previously described, while it is a simple matter to determine whether one or other of the switches was actuated during the drop test by means of the actuation of the pump, it is impossible to determine which of the two switches actually caused this to happen. By using the apparatus of the invention and interposing it in the communication link between the two sensors and the pump itself, it is immediately evident from the apparatus which of the two sensors was actuated.
The apparatus preferably stores at least the last pressure drop test results so building inspectors, fire officers and the like can verify that each switch operated on the day of the weekly fire sprinkler test.
The invention can prove that the switch is wired correctly, has power and that the switch operates. It cannot verify that the pump has started-this is done by means of the weekly drop test done by an operative. The operative must note the pressure that each switch operated and that they would have worked if the other one failed.
Jockey pumps in sprinkler systems are often used to maintain the system pressure in the event of a leak, and they also operate first in a fire situation. If a jockey pump does not work when it is required, a fire or main pump will start, and in the light of the fact that the main pumps in conventional installations are linked to the fire brigade by remote alarm, their activation often results in a fire brigade call out. This is inconvenient and can also be expensive. The apparatus of the present invention prevents this from occurring.
Jockey pump failure is often due to:

a pump running for too long-caused by an open pipe (for example a standpipe or the like; water supplied to sprinkler systems is generally free and therefore unscrupulous persons knowing this often take advantage of this fact);
a pump cutting in and out too often causing the motor or starter to burn out-this can be caused by incorrectly sized pump/ orifice plates or large leaks.

It is preferable that the apparatus of the present invention is capable of monitoring both of these conditions enabling installers to see a snapshot of the system parameters, in particular the jockey pump pressure switch activity and pressure readings, for example once a week, when they revisit site to perform the weekly drop test. If the panel indicates a fault it will offer further evidence in the way of; time of fault and duration or number of faults.
With this information and engineer may be able to rectify the system prior to a failure and unnecessary cost and downtime of the system. Volt free contacts may be used in the apparatus enabling a signal to be run to the building management system to warn of the problem when it occurs.
Further features and advantages of the invention of the will become apparent upon a reading of the following description of an exemplary embodiment, made with reference to the accompanying drawings, in which:

Figure 1 shows a typical prior art sprinkler supply installation in schematic form.
Figure 2 shows an example of a prior art pump initiation test assembly 10.
Figure 3 shows schematically the prior art pump initiation test assembly 10 of Figure 2, and
Figure 4 shows a schematic representation of the apparatus according to the invention connected to the pump initiation test assembly and then to the jockey pump.

Referring to Figure 4, a schematic representation is shown wherein the two pressure sensors 15A, 15B each have associated therewith two identical and simultaneously operable electrical switches (not shown). The first switch of each pair of switches is electrically connected together effectively in series in a circuit with the pump such that the actuation of the pressure sensor associated with either of these switches causes the actuation of the pump.
The second switch of each switch pair is wired independently of the first switch of the particular pair and feeds display means in the form of a programmable logic controller (PLC) 40 (which may include simple light display means) or most simply, a light. It is envisaged by the applicant that a suitable (PLC) may include data capture, processing and display purposes.
In a conventional drop test (as described above), the normally open valve 12 is closed and the normally closed valve 13 is closed whereby the fluid pressure in the conduit 11 starts to fall. As this occurs, one or other of the pressure sensors 15A, 15B, whose pressure thresholds are marginally different from one another, will attempt to fire the jockey pump P to which it is indirectly connected through the apparatus 40. On actuation of the switch pair associated with the first sensor, either a light is illuminated and/or data is captured.
As the pressure in conduit 11 falls further, the second of the two pressure sensors then also attempts to trigger the jockey pump (as is soon to be required by law), and again (redundantly as a result of said pump already having been actuated by the above) the communication between the second sensor and the jockey pump is achieved indirectly through the apparatus 40. The actuation of the second pair of switches therefore achieves nothing as far as said pump is concerned, but nevertheless causes illumination and/or data capture indicative of the fact that the second sensor was actuated.
Where the PLC 40 is provided, when either of the pairs of switches is actuated, a control signal is sent to the apparatus, which is essentially an information, logging and basic display apparatus, said information being basically a snapshot of the characteristics of the fluid pressure in the conduit 11 at the time of actuation, and also the time and date of that actuation. This information is stored in the apparatus for later inspection for both pressure sensors, and basic lights 42-46 provide an indication of apparatus power, and also which of the two pressure sensors 15A or 15B was actuated first as the pressure drop test was carried out.
It is to be mentioned that the electronic component may be housed within the apparatus which can be locked so that access can be gained thereto only by those with relevant keys, and furthermore the electronic device may include a simple LED screen by which the information concerning the various tests performed over a predetermined period (for example a month or two) may be viewed thereon. Additionally, the device may allow for connection of a computer which may then be able to download the information for analysis.

Claims

A pump initiation test assembly for a sprinkler system in which there are provided at least a pair of pressure sensors provided in the same test section of pipework within said assembly and communicating with the same chamber containing pressurised fluid within said pipework, said pressure sensors having associated therewith at least two switches whose state changes simultaneously when the fluid pressure within said chamber becomes less than an adjustable pressure threshold of the sensor, a first of said switches of each sensor being electrically connected to at least one pump so as to cause actuation thereof when the fluid pressure within said chamber changes to a value greater or less than said threshold,
characterised in that
the first switches of each sensor which are electrically connected to said pump are effectively connected in series such that the actuation of either of said switches causes actuation of the pump, and further characterised in that the second switches of each sensor are electrically connected, substantially electrically independently of said first switches, to display means capable of indicating which of the particular sensors is actuated during a test when the fluid pressure becomes less than said threshold.
Apparatus according to claim 1 characterised in that the threshold values of each sensor are set to different values to ensure that one of the sensors, and thus the particular pair of switches associated with that sensor, is actuated before the other during a conventional pressure drop test.
Apparatus according to claim 1 or 2 characterised in that the display means includes a simple light suitably mounted and located proximate the test assembly.
Apparatus according to any preceding claim characterised in that the apparatus includes electrical detection means communicating with each pressure sensor and/or associated switches, and memory means associated therewith for storing snapshot information relating to the operation of said sensors, said display means including a display panel on which said snapshot information can be viewed.
Apparatus according to any preceding claim characterised in that both switches associated with each sensor are identical in that their states change in an identical and simultaneous manner when the pressure sensor is actuated.
Apparatus according to any preceding claim characterised in that the display means includes a programmable logic controller (PLC).
Apparatus according to claim 4 or claims 5 and 6 when dependent on claim 4 characterised in that apparatus is further capable of receiving information concerning the day, date, and time of a particular switch actuation and the chamber pressure at which that actuation occurred, said snapshot information being capable of being stored for a large number of individual, separate pressure drop tests.
Apparatus according to claim 4 or claims 5, 6, 7 when dependent thereon wherein the display means further monitors the functioning or otherwise of the pumps to which the first switches in each switch pair associated with the pressure sensors is connected.