GB2347721A - A coupling unit for use in constructing a pump initiation test assembly - Google Patents

Abstract

A coupling unit 29 for use in constructing a pump initiation test assembly, said unit comprising a monolithic block (30, fig 5) provided with a through passage extending between an inlet connection 35 for coupling to pipework of a sprinkler installation and an outlet connection 42 for coupling to a drain. The unit also comprises a mounting for a control valve within the passage. A first portion of the passage lies between the inlet connection and the control valve, and a second portion of the passage extending from the control valve towards the outlet connection. The second portion of the passage is provided with first coupling means 41 for coupling to a pressure gauge an a second coupling means for coupling to a pressure sensor. Alternatively, the pressure sensor may be mounted within the block so as to receive liquid pressure from the second portion of the passage.

Description

Pump Initiation Test Assemblies The present invention relates to assemblies for testing and/or adjusting pump initiation in sprinkler systems.

Automatic sprinkler systems such as are used for dealing with fires, for example, comprise a sprinkler head, or more often an array of sprinkler heads. The head or array is located within an area of a building or compartment to be protected, for example on a ceiling or wall (s), and in response to a stimulus a pump is started for supplying the liquid to be sprinkled, often plain water, to the sprinkler head (s). In the case of a fire sprinkler system, the stimulus could be the presence of heat, light or smoke from the fire.

In a common form of fire sprinkler system, the stimulus is heat, and the sprinkler heads are sealed, but filled under an operating pressure with the liquid to be sprinkled.

The operating pressure is maintained within a predetermined design operating pressure range, commonly in the region of 7 to 9 Bar, although this is a matter of design dictated at least in part by what is to be protected and where it is located. This type of pressure level is conveniently obtained by the use of a jockey pump supplied from a reservoir, the jockey pump being energised if the pressure is sensed to drop below a predetermined value defining the bottom end of the predetermined range, for example as sensed by 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 head may respond in such manner to the heat source.

When only one head is in action, it may be that the jockey pump itself is sufficient to maintain a supply of liquid thereto at a sufficient pressure. However, that may not be the case, or the jockey pump may be unable to provide a sufficient flow if more than one head is energised at the same time. In such cases it is common to provide additional pumps which are energised is progression as the sensed pressure falls below a corresponding sequence of reduced pressure levels, so as to maintain the flow of liquid to the heads.

A fire sprinkler system is an important safety measure. The actuation thereof in cases of real need is vital, but, correspondingly, false actuation thereof is very undesirable, insofar as the sprinkled water can cause considerable damage to the building or contents and inconvenience to staff or customers. It is clearly desirable, therefore, that such a system is well and accurately regulated to ensure it operates only when needed. This in turn makes it necessary to ensure that the pressure at which the pump or pumps are energised is correctly adjusted.

The sprinkler industry is governed by the LPC (Loss prevention Council), which provides a manual for fire sprinkler installations, with reference to the relevant British standards. The LPC sets guidelines and rules which should be followed, in addition to providing approval to products and companies.

LPC Technical Bulletin TB 10 deals with automatic starting of sprinkler pumps, and provides a basic layout for that function, with cross references within the LPC rules to determine which valves, gauges and switches are suitable for fabrication of the layout.

The layout enables the correct setting of a pressure sensitive electrical switch, and also enables testing to ensure that the switch, and components operated by the switch, will respond correctly to a pressure drop in the installation.

In the prior art, the layout has been put into place using individual malleable iron fittings for interconnecting of other working parts of the layout, such as the valves, gauges and switches just mentioned. 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 with increasing demand (more sprinkler heads in operation) the jockey pump 22 is initially started, and thereafter pump 22a and 22b in progression. The jockey pump also operates to maintain the pressure in the system in the design working pressure range 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 progressively called into play.

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 11 are a pressure gauge 14 and a pressure sensitive electrical switch 15, for example operated by a diaphragm sensing the pressure in pipework 11. 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 valvel2 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 disconnects 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 per se. Should the critical level be outside of specification, the switch is adjusted and the assembly retested 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.

The assembly 10 of Figures 2 and 3 includes operational components in the form of the valves 12,13, and 18, the gauge 14 and switch 15, and the restrictor 12a if provided. It will be appreciated that the assembly shown in Figure 2 includes a large number of additional components whose sole purpose is to provide for interconnections between the operational components. These additional components are commonly in the form of ferrous (malleable iron) fittings, and the restrictor 20 also commonly includes or is a ferrous component, or requires the insertion of a nonferrous plate which again introduces additional labour and unreliability, etc.

Because of the large number of connections involved, the assembly tends to be prone to leaks, and either takes up an unwarranted volume ("pumphouse") or involves difficulties in making the assembly as small as practicable (this also makes leaks more likely). Large assemblies are not favoured, since although safety is important, the volume occupied by the assembly is regarded as non-productive. In addition, the large number of exposed threads also require painting after installation and upon deterioration thereof.

The large number of connections also means that construction of the assembly is time consuming and labour intensive. Construction is frequently performed on site to ensure that the assembly can be fitted in the restricted space (pumphouse) allowed by the customer, and this in itself can increase time and labour costs. Such assemblies therefore end to be custom made, and care is needed during installation to ensure that there is correct alignment of pipes etc. for correct connections to be made.

Furthermore, the loops 17 are often formed of bent small-bore pipe, even if strictly this is not permitted by the LPC rules.

Again, the large number of components increases the risk of failure of one component. Should this occur, there is the additional difficulty of breaking and the remaking a plurality of connections in order to remove and replace the offending component. If the replacement component has different physical dimensions from those of the original component, further difficulties may arise, particularly where it is connected at more than one place in the assembly.

The present invention provides a coupling unit for use in constructing a pump initiation test assembly, said unit comprising a monolithic block provided with a through passage extending between an inlet connection for coupling to pipework of a sprinkler installation and an outlet connection for coupling to a drain, said unit comprising a mounting for control valve within said passage, a first portion of said passage lying between said inlet connection and said control valve, and a second portion of said passage extending from said control valve towards said outlet connection, the second portion of the passage being provided with first coupling means for coupling to a pressure gauge, and second coupling means for coupling to a pressure sensor.

The present invention also provides a coupling unit for use in constructing a pump initiation test assembly, said unit comprising a monolithic block provided with a through passage extending between an inlet connection for coupling to pipework of a sprinkler installation and an outlet connection for coupling to a drain, said unit comprising a mounting for control valve within said passage, a first portion of said passage lying between said inlet connection and said control valve, and a second portion of said passage extending from said control valve towards said outlet connection, the second portion of the passage being provided with first coupling means for coupling to a pressure gauge, and wherein a pressure sensor is mounted in the block so as to receive liquid pressure from the second portion of the passage.

The block may be of metal, and while it could be a ferrous metal this brings with it the attendant disadvantages associated with ferrous components as mentioned above.

A preferred non-ferrous metal is brass, and the block is preferably extruded rather than cast to avoid casting holes in the block, bearing in mind that this is a safety component, and is under a significant liquid pressure at all times. Nevertheless, under certain circumstances the block could be formed of a non-metallic material, for example a plastics or resin material, and this could be strengthened by reinforcing material, for example carbon fibres.

Further features and advantages of the invention of the will become apparent on perusal of the appended claims, and 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 sprinkler supply installation in schematic form.

Figure 2 shows an example of a conventional pump initiation test assembly 10.

Figure 3 shows in more schematic form the pump initiation test assembly 10 of Figure 2.

Figure 4 shows in perspective view a coupling unit 29 according to the present invention; and Figure 5 shows a side cross-sectional view of the unit 29 of Figure 4.

As shown in Figure 4, the unit 29 comprises a monolithic extruded cuboidal brass block 30 having two major faces joined by four side faces 31 to 34. The face 31 is provided with an inlet connection 35 (for example a threaded female connection) for coupling to pipework (16, Figure 3) leading to the sprinkler installation. From the inlet connection, a passage 36 leads to an intersection with a drilling 37 extending between the faces 32 and 34, which faces extend normally to the face 32. The passage 37 may be formed by drilling from the face 36, and includes a first portion 38 extending from the face 31, an intermediate portion 39 of slightly reduced diameter leading to a restricted diameter end portion 40 which actually enters the drilling 37.

The drilling 37 is provided with a coupling 41 at the face 32 for a pressure gauge, and with a coupling 42 at the face 34 for connection to a gate valve for passing liquid to a drain. Both couplings may be in the form of female threads.

A second drilling 43 runs from the face 31 to intersect with the drilling 37 and includes means 44 for coupling to, or mounting, a pressure sensitive switch at the face 31, for example a female thread. Neither of drillings 36,43 extends as far as the face 34, which is opposed to face 31 and is not drilled in this embodiment.

A further drilling 45 extends from the face 32 to intersect with the drilling 36, and is provided with means 46 at the face 32, for example a female thread, for insertion of a plug or other sealing means. The drilling comprises an initial wide diameter portion 47, which continues across the drilling 36 to provide a valve seat 49 or housing on the opposite side. From the base of the valve seat the drilling continues as a reduced diameter portion 48 until it enters the drilling 43.

A non-return valve (not shown) is inserted into the drilling 45 so as to be secured in the housing or seat 47. If the portion 47 acts as a valve seat in its own right, the nonreturn valve to be inserted will comprise, for example, a closure member, spring and the plug to be inserted in coupling means 45.. If the portion 47 acts as a housing, the valve will also comprise the valve seat, and will need to be suitably accornmodated and sealed within the portion 47 by means known per se, for example by threaded connection. The non-return valve acts to permit liquid flow only from the drilling 43 to the drilling 36 and not vice versa.

The restricted diameter end portion 39 of the drilling 36 is formed to accommodate a ball valve (not shown). For access to the ball valve for operation thereof, a further drilling or broaching 50 extends from one of the major faces of the block to intersect the portion 39. The end of the portion 39 could be shaped to act as a seat, or part seat, for the ball valve, but in this embodiment the ball valve includes a cylindrical housing of an appropriate diameter which is inserted into the block 30 through the portion 38 and sealingly secured within the intermediate diameter portion 39 by means known per se, for example a threaded connection so as to be in alignment with the broaching 50.

It will be appreciated by the reader that the block 30 is formed so as to replace a large number of connections relative to the assembly of Figures 2 and 3, and serves as a single connecting piece for the gate valve, sprinkler installation pipework, pressure gauge and pressure sensitive switch. It also facilitates the provision of an internal ball valve and non-return valve with a reduced number of connections and component parts. With the block 30 being monolithic, and having so few connections, the chances of a leak occurring, or of failure under pressure, are much reduced. The reduced number of external connections also means that, if some (minor) leaks do occur, for example in association with the valves or restrictor, they will be internal of the block and so inconsequential.

The reduced number of connections, and the facility of providing a block prefitted with the ball valve and non-return valve reduces the time and effort in making an installation. There are only five connections to the block compared with some twenty five to thirty threaded joints in a conventional installation.

Furthermore, only the inlet 35 couples to the main sprinkler installation pipework so that precise alignment of parts is greatly reduced or eliminated. The only necessary alignment would be to enable coupling both to the main sprinkler installation pipework and the connection to the drain gate valve if this is firmly plumbed between a drain and the block 30 (this will apply particularly in the case of a common drain for a plurality of initiation assemblies).

As the block 30 with restriction 40 and the incorporated valves can be made of a nonferrous material, corrosion is greatly reduced or eliminated, with consequent savings in maintenance and repairs, and there is no need to paint or otherwise protect exposed non-ferrous threads. Furthermore, the one-way loops which were previously of bent small bore pipework (17) are now formed integrally (45 to 49) within the block 30.

Again, the one-way valve in the assembly controlling the jockey pump could be omitted if desired.

A further advantage is that the complete assembly is much more compact than a corresponding assembly made of discrete components, probably by a factor of around 4, thereby saving valued pumphouse space. By incorporating an integral flow restriction 40 in the drilling 36, no separate flow restrictor is required.

Although a mechanical type pressure switch is conventionally used, it is also possible to use other types of pressure sensor or electronic switch to which the unit 27 is responsive. The output of such a sensor could be digital (on/off) to provide a thresholding function, particularly if the level of the threshold can be adjusted at the sensor. However, the output could also be analogue, with a thresholding function built into the unit 27, in which case adjustment of the reduced pressure level at which the pump is started is performed at the unit 25. in particular, the sensor could be, for example, a semiconductor or other sensor of a size which is reduced relative to a conventional diaphragm switch, thereby again saving on space.

The reliability of solid state pressure sensors is such that maintenance of the assembly is again reduced.

Furthermore, adaptation of the assembly illustrated in Figures 4 and 5 to use a solid state sensor can simplify manufacture of the block. By virtue of the relative smallness of the sensor, it can be located anywhere so long as it is exposed to the pressure between the ball valve and the gate valve. Thus one suitable modification of the embodiment would do greatly reduce the diameter of the drilling 43, so reducing the necessary size of block 30, so long as it still enables sufficient fluid coupling to the drilling portion 48. The sensor could be secured in the drilling 43 by any known means, sealing being facilitated by the smallness of the drilling. If the one-way loop is omitted entirely (not preferred), and the sensor appropriately relocated, the drilling 43 could be omitted entirely together with most of drilling 37.

It will be appreciated that in the embodiment there are four main drillings 36,37,43, 45, each extending from at least one face of block 30, and therefore readily formed.

As shown, they may be produced by drilling from only the two faces 31,32.

Furthermore, the modification to the drillings, such as reduced diameter portions, and the provision of threads or seatings are also readily effected from the faces 31,32 with no specialised techniques being necessary.

It should also be appreciated that although the embodiment shows one particular arrangement of drillings, variations are readily and easily obtained. For example, by extending drilling 43 to the face 33, and stopping drilling 37 short of the face 34, the position of the coupling 42 to the drain gate valve can be altered. Similarly a drilling from the face 33 into the drilling 37, whether or not opposed to the drilling 36, could allow for an alternative mounting of the gauge, pressure sensor, or drain gate valve, with the corresponding existing coupling being blanked or not formed.

In a modification of the embodiment, the drilling 37 is modified, to include a gate valve, or a seating therefor, located between connection to the drilling 43 and the coupling 42, which in this case may then be connected directly to the drain pipework (19). A suitable exemplary modification is the provision of an internal thread for accommodating the valve, and a broaching from a major face for operation of the valve, similar to the manner in which the ball valve is accommodated.

Claims (23)

1. A coupling unit for use in constructing a pump initiation test assembly, said unit comprising a monolithic block provided with a through passage extending between an inlet connection for coupling to pipework of a sprinkler installation and an outlet connection for coupling to a drain, said unit comprising a mounting for a control valve within said passage, a first portion of said passage lying between said inlet connection and said control valve, and a second portion of said passage extending from said control valve towards said outlet connection, the second portion of the passage being provided with first coupling means for coupling to a pressure gauge, and second coupling means for coupling to a pressure sensor.

2. A coupling unit for use in constructing a pump initiation test assembly, said unit comprising a monolithic block provided with a through passage extending between an inlet connection for coupling to pipework of a sprinkler installation and an outlet connection for coupling to a drain, said unit comprising a mounting for a control valve within said passage, a first portion of said passage lying between said inlet connection and said control valve, and a second portion of said passage extending from said control valve towards said outlet connection, the second portion of the passage being provided with first coupling means for coupling to a pressure gauge, and wherein a pressure sensor is mounted in the block so as to receive liquid pressure from the second portion of the passage..

3 A coupling unit according to claim 1 or claim 2 and including a said control valve.

4. A coupling unit according to claim 3 wherein said control valve is a gate, ball or needle valve.

5. A coupling unit according to claim 4 wherein said control valve is a ball valve.

6. A coupling unit according to any preceding claim wherein the second portion of the passage terminates in the outlet connection, the outlet connection being for coupling to a valve connected to a drain.

7. A coupling unit according to any one of claims 1 to 6 and including a mounting for a drain valve formed in the block between the second portion of the passage and the outlet connection.

8. A coupling unit according to claim 6 or claim 7 and including said drain valve.

9. A coupling unit according to claim 8 wherein said drain valve is a gate, ball or needle valve.

10. A coupling unit according to claim 9 wherein said drain valve is a gate valve.

11. A coupling unit according to any preceding claim wherein a bypass passage is provided in the block between the first and second portions of the through passage to bypass the control valve.

12. A coupling unit according to claim 11 wherein said bypass passage includes a mounting for a one-way valve permitting flow only in a direction towards the inlet connection.

13. A coupling unit according to claim 12 and including a said one-way valve.

14. A coupling unit according to any preceding claim wherein a constriction is formed in the through passage between said control valve and said second passage portion.

15. A coupling unit according to any preceding claim wherein the block is of metal.

16. A coupling unit according to claim 15 wherein the block is of brass.

17. A coupling unit according to any preceding claim wherein the block is of extruded material.

18. A coupling unit according to any preceding claim wherein the first passage portion is defined by a first drilling extending from a first face of the block.

19. A coupling unit according to claim 18 wherein the second passage portion includes a second drilling extending from a second face of the block so as to intersect with the first drilling.

20. A coupling unit according to claim 19 wherein the second passage portion includes a third drilling extending from the first face of the block so as to intersect with the second drilling.

21. A coupling unit according to claim 20 and any one of claims 11 to 17 wherein the bypass passage includes a bypass drilling extending from said second face, or an opposed face so as to intersect with the first and third drillings.

22. A coupling unit for a pump initiation test assembly substantially as hereinbefore described with reference to Figures 4 and 5 of the accompanying drawings.

23. A pump initiation test assembly comprising a coupling unit according to any preceding claim.