GB2550167A

GB2550167A - A liquid dispensing system

Info

Publication number: GB2550167A
Application number: GB1608224.0A
Authority: GB
Inventors: Gerard O'brien Michael
Original assignee: Packaging Innovation Ltd
Current assignee: Packaging Innovation Ltd
Priority date: 2016-05-11
Filing date: 2016-05-11
Publication date: 2017-11-15
Also published as: GB201620345D0; GB2550232A; GB201608224D0

Abstract

A liquid dispensing system 1 according to a first aspect of the invention comprises a liquid dispenser 2 and two receptacles 3, 4, 5 for liquid dispensed from the liquid dispenser 2, each receptacle 3 to 5 having an identifier 8, 9, 10 associated with it, wherein at least two of the identifiers are of different types to each other. The liquid dispenser 2 comprises a reader 11 for the identifiers and is arranged to dispense a first volume of liquid in response to reading and identifying an identifier 8 of a first type and to dispense a second volume of liquid, different to the first volume, in response to reading and identifying an identifier 9 of a second type. The dispenser may also record the identifiers read for analysis, possible by a system manager. The reader may be an RFID reader and the identifiers may be RFID tags. Another aspect relates to a valve assembly (28, Fig.8) comprising a diaphragm (34, Fig.8) and which may be used with a source of pressurised liquid to permit the liquid to be dispensed at a relatively constant rate.

Description

A Liquid Dispensing System A first aspect of the present invention relates to a liquid dispensing system particularly suitable for dispensing a concentrate, or for dispensing a catalyst for activating a concentrate, but the dispensing system may have other applications. A second aspect of the invention relates to a valve assembly which may permit small quantities of liquid to be dispensed in a controlled and accurate manner, whilst leaving only minimal quantities of the liquid being dispensed open to the atmosphere on the outlet side of the valve assembly. The valve assembly is particularly applicable to a liquid dispenser for use in a liquid dispensing system in accordance with the first aspect of the invention but the valve assembly may have other applications.

In industrial cleaning applications, large volumes of liquid are often necessary for cleaning relatively large areas, for example floors, working surfaces or walls, and this normally necessitates that a chemical be provided in a concentrate form to be subsequently mixed on site with water. This requires that the concentrate be of a considerable strength, which may result in it being classified as a hazardous chemical and subject to rules and regulations regarding handling of the concentrate, storage of the concentrate and use of the concentrate. This may all add to the complexity and cost of a cleaning operation.

One advantage of providing a cleaning chemical in a concentrated form for subsequent dilution is that the same chemical may be diluted to different strengths depending on the application it is to be used for, for example it may be used in a relatively weak form for the general cleaning of large surface areas, but may be used in a more concentrated form, or even neat, when cleaning smaller heavily soiled areas, where it may be dispensed out of a trigger bottle or the like. A liquid dispensing system in accordance with the present invention may be used for controlling the dispensing of a concentrate for such applications, however alternatively it may be used for dispensing a catalyst for a cleaning solution.

According to a first aspect of the present invention there is provided a liquid dispensing system comprising a liquid dispenser and at least two receptacles for liquid dispensed from the liquid dispenser, each receptacle having an identifier associated with it wherein at least two of the identifiers are of a different type to each other, wherein the liquid dispenser comprises a reader for the identifiers and is arranged to dispense a first volume of liquid in response to reading and identifying an identifier of a first type and to dispense a second volume of liquid, different to the first volume, in response to reading and identifying an identifier of a second type.

The identifiers may be of a "different type" to each other because they contain different data, or they may additionally be visually distinguishable, possibly by colour, in a manner that is related to the data they hold and which is to be read by the reader of the dispenser. A liquid dispensing system in accordance with the present invention permits different identifiers to be associated with different receptacles, for example a trigger bottle may have a first type of identifier associated with it, possibly by being attached to it and a bucket may have a different type of identifier associated with it. Thus, when an identifier is presented to and read by the reader, a first type of identifier, for example associated with a trigger bottle, will cause the dispenser to dispense a volume of liquid appropriate for that receptacle. However when a second, different, type of identifier is presented associated with a different receptacle type, the dispenser will dispense a second volume of liquid different to the first volume, which volume is appropriate for that second type of receptacle. This ensures a correct volume is dispensed, which may prevent over dispensing of a chemical, which may be beneficial for economic, safety or environmental reasons, or a combination of these. It may also ensure that a sufficient volume of a chemical is dispensed to ensure a resultant solution is of a sufficient strength to permit it to reliably perform its intended task, which may be particularly important if the resulting solution is to be used for bacterial control, for example in a food preparation area, a hospital theatre of the like.

It is proposed that chemical concentrates used for cleaning, which presently contain an active and thus potentially hazardous component, be substituted with concentrates which contain an inactive and thus non-hazardous component that is subsequently activated by a catalyst for a limited period of time.

An advantage of this is that the concentrate in its inactive state may be transported and stored as a non-hazardous liquid. A catalyst may then be added, either to the concentrate or a solution containing the concentrate, immediately prior to use. If the concentrate is diluted before the catalyst is added then the concentrate need never be active, or thus or thus potentially hazardous, in its undiluted full strength state. A further advantage of a catalyst based system is that the dilute cleaning solution may again become inactive after a certain period of time. Thus any residual solution on surfaces may be active to perform its function, for example to kill bacteria, and then subsequently become inactive and thus safe. Also any remaining solution may be safely disposed of.

With a catalyst based cleaning system, a liquid dispensing system may be required that ensures that a correct volume, or dose, of catalyst is dispensed to ensure a chemical is completely activated. Also, with certain types of catalyst it can be important that the required dose is not exceeded and that the volume of catalyst is matched to the volume of concentrate. This is because some catalysts may result in unpleasant odours which will not be confined to any solution in a receptacle that containing excess unused catalyst, but will also result in odours being given off from the possibly large surface areas which have been cleaned. Therefore it is important, particularly in the case of cleaning contractors, to have a system which can ensure a catalyst is correctly measured and dispensed. Thus, the present invention may be of particularly applicable to such a use, ensuring a correct volume of a catalyst may be dispensed to a receptacle of a particular size or for a particular purpose.

The liquid dispenser in accordance with the present invention, may further comprise an electronic memory arranged to receive and record data from the identifiers that have been read by the reader. The system may further comprising means for transmitting or displaying this data. This may thus provide a record to a system manager of not only the quantities being dispensed, but also (or alternatively) of the different types of receptacles the liquid is being dispensed to and thus possibly what the liquid is being used for.

As the liquid dispensing system may record information other than volume dispensed, two identifier of different types could result in the same quantity of liquid being dispensed, but here the different receptacle types will still have been identified by the dispenser.

The system may comprise means for displaying the data or to permit the data to be interrogated by connection (possibly wirelessly or by use of the internet) to a computer or the like. Advantageously, the dispenser is arranged to be reprogrammable to recognise different types of identifier. Thus, as different tasks or different quantities of chemical may be required the dispenser may be updated accordingly and new identifiers generated for attaching to appropriate receptacles.

The dispenser may be arranged to provide an audible alarm or prevent dispensing if an identifiers is identified which is not of a predetermined type. In this manner, if a person presents an incorrect receptacle for receiving liquid from the dispenser, the dispenser may be automatically prevented from incorrectly dispensing or the person may be warned that the identifier and thus the receptacle is of an inappropriate type. A liquid to be dispensed may have an identifier associated with it, for example by an identification device such as Radio Frequency Identification Device (RFID) tag, barcode or identification device being placed on a container or packaging associated with the liquid or being carried by a person responsible for replenishing the dispenser. This may then be read by the reader and identified by the dispenser, possibly before the product is inserted into the dispenser. This may then be used to reprogram the liquid dispenser to change the types of identifier which result in an audible alarm and/or prevent product being dispensed, or the identifier associated with the product to be dispensed may cause the volume of liquid dispensed to be changed for any particular identifier identified by the reader. This enables the dispenser to be used with different types of liquids, for example if a more concentrated liquid is dispensed then the volumes dispensed may be adjusted accordingly.

The identifiers and reader may comprise any appropriate system, such as a barcode system, however a radio frequency identification (RFID) tag based system is preferable, for it permits the identifier to be identified by the reader by being brought into close proximity to the reader, without the requirement for any specific alignment (as in the case of a barcode reader) or other correct or contact positioning.

Other advantages of using identification device tags are that it will not normally be possible for cleaning staff to tamper with these, they can be relatively robust and substantially immune to spillage or even immersion.

Advantageously, the dispensing system comprises a plurality of receptacles each receptacle being visually associated, by its shape, colour or marking, with one of a plurality of groups of receptacles, where each group of receptacles is intended to have a specific purpose and where the identifier on each receptacle contains information relating to the group with which that receptacle is associated. For example, a group of receptacles may comprise a trigger bottle, a small bowl and a bucket. These, for example, may all be coloured blue or marked in some other way that identifies each of those receptacles as belonging to a particular group. That particular group may then be associated with a particular task such as general light cleaning duties. A different group of receptacles, which again could comprise a trigger bottle, a small bowl and a bucket, may belong to a different group and may be coloured red, or uniquely identified in some other way, as belonging to another group of receptacles. This may signify that these are to be used, for example, for sterilisation purposes. The identifiers associated with the different groups of receptacles may therefore cause different volumes of a liquid to be dispensed by a dispenser to the same type of receptacle. For example, a different quantity may dispensed to a red bucket than to a blue bucket, thus the quantity dispensed is dependent on the task to be performed as well as the type of receptacle. Alternatively the volume dispensed may be the same regardless of the group with which a receptacle is associated, but the group to which the receptacle is associated may be recorded for management purposes.

The liquid dispenser may comprise an electric pump or valve which is operated for a period, or at a rate, determined by an identifier read by the identifier reader, permitting an appropriate volume to be dispensed.

The liquid dispensing system may preferably comprise a dispenser which is arranged to be portable and handheld. In this manner, it may be held over receptacles into which the liquid is to be dispensed, for example over a bucket, cleaning machine or a similar receptacle.

According to the second aspect of the invention there is provided a method of dispensing a liquid from a liquid dispenser as described above, the method comprising selecting a receptacle in dependence on a type of task to be performed, placing an identifier on the receptacle that can be read by the liquid dispenser and dispensing liquid into the receptacle. An appropriate identifier may be placed on a receptacle by a system manager of the liquid dispensing system, with a cleaner or cleaners subsequently dispensing a liquid into the receptacle.

The method may comprise, in no particular order, placing a concentrate in the receptacle appropriate for a task, diluting the concentrate and then dispensing from the liquid dispenser a catalyst for that concentrate.

According to a third aspect of the present invention there is provided a valve assembly comprising a housing, a diaphragm within the housing, the housing and diaphragm defining a chamber in liquid connection with a liquid inlet of the valve assembly, the valve assembly comprising biasing means for biasing the diaphragm to a first position towards the chamber, with any pressure exerted by a liquid at the liquid inlet urging the diaphragm to a second position away from the chamber, the valve assembly further comprising a nozzle at an outlet of the valve assembly and a valve located in the nozzle which valve includes a valve plug for closing the nozzle, the valve plug being connected to the diaphragm so that when the diaphragm is in the first position the valve is closed and when the diaphragm is in the second position the valve is open, the valve assembly further comprising a passage between the chamber and the nozzle through which liquid passing through the valve assembly must flow, the passage having a restriction upstream from the valve, the dimensions of the restriction being such that it defines a liquid flow path which is smaller in cross sectional area than the cross sectional area of the liquid flow path of the valve when the valve is open. A valve assembly in accordance with this third aspect of the invention may be used with a source of pressurised liquid, to permit the liquid to be dispensed at a relatively constant rate when the liquid at the inlet is pressurised, the pressurised liquid acting to open the valve when the pressure builds beyond a certain threshold and close the valve when the pressure drops below that threshold. Thus, control of the pressurised source of liquid instant on the valve may be used to open and close the valve without any separate actuator mechanism being required to operate the valve.

The valve being located in the nozzle may be arranged to limit, to an insignificant quantity, the quantity of a liquid downstream of the valve after a dispensing action. This may be particularly advantageous if the valve assembly is being used to dispense a catalyst, for example peracetic acid, which is particularly odorous.

The restriction in the valve assembly may enable the flow rate through the valve to be relatively constant even though the pressure of liquid at the inlet of the valve assembly may vary within a limited range during dispensing, or during subsequent dispensing cycles. This may permit pumps to be used with the valve assemblies, without the need to calibrate each pump / valve assembly pair.

In addition to the above advantage the restriction, being located remote from and upstream of the outlet nozzle, may also ensure that the pressure at the outlet is never sufficient to cause a potentially hazardous jet or spray of liquid from the nozzle, even as the valve opens or closes.

Advantageously, the cross-sectional area of the liquid flow path of the restriction is less than half the cross-sectional area of the liquid flow path at the valve when the valve is open, this ensuring that the pressure can never build at the valve to an extent where a jet of liquid could be sprayed from the nozzle.

Advantageously, the cross-sectional area the liquid flow path at the restriction is less than 3.2 mm2 and more preferably less than 0.8 mm2.

The biasing means for the diaphragm may be a spring or similar biasing means or may be the inherent resilience of the diaphragm itself.

The valve plug may be formed in or at the end of a valve stem extending directly to the diaphragm, with a seal around the stem sealing between the stem and the chamber ensuring that a liquid being dispensed through the valve assembly must pass through the restriction.

According to a fourth aspect of the present invention there is provided a liquid dispenser comprising a reservoir for a liquid, a pump, a valve assembly as described above and a actuator, the pump being arranged to pump liquid from the reservoir through the valve assembly at a substantially constant pressure, such that the quantity of liquid dispensed is substantially proportional to the time the pump is actuated. This provides a simple means of controlling the dispensing of the liquid by controlling only the actuation of the pump. Preferably the pump is a centrifugal pump, where switching off the pump permits fluid to flow back through the pump, immediately allowing the pressure to fall in the valve assembly as the diaphragm closes the valve, thus avoiding any jetting or spraying of liquid from the valve at the outlet nozzle.

Advantageously, the actuator includes a timer which controls the period of operation of the pump. A liquid dispenser as described immediately above may be advantageously used in the liquid dispensing system described earlier.

One embodiment of a liquid dispensing system in accordance with the present invention, incorporating a liquid dispenser and valve assembly also in accordance with the present invention, will now be described below, by way of example only, with reference to the accompanying figures, of which:

Figure 1 illustrates a liquid dispensing system in accordance with the present invention;

Figures 2 to 5 help illustrate the working of the dispensing system of Figure 1 and a method by which the liquid dispensing system of Figure 1 may be operated;

Figure 6 is a front elevation of the liquid dispenser of the liquid dispensing system of Figure 1, with a front cover removed;

Figure 7a is perspective view of the internal components of liquid dispenser;

Figure 7b is a side elevation of the components illustrated in Figure 7a;

Figure 7c is a front elevation of the components illustrated in Figures 7a and Figure 7b;

Figure 8 is a cross-section through a valve assembly of the dispenser illustrated in Figure 1, in a closed configuration; and

Figure 9 is a cross-section through the valve assembly of Figure 8 when the valve assembly in an open configuration.

Referring now to Figure 1, a liquid dispensing system, indicated generally as 1, comprises a liquid dispenser 2, a plurality of receptacles comprising a small bucket 3, a large bucket 4, a trigger bottle 5 and a mobile 6 connected to the internet, represented by cloud 7.

Each of the receptacles 3 to 5 has associated with it an identification device tag, such as a Radio Frequency Identification Device (RFID) 8 to 10 respectively, each of which can be interrogated (or read) by an identification device reader 11 on the dispenser 2, such as an RFID reader. Usage data including amounts dispensed, frequency, times, dates and receptacles used are recorded on memory device 15.

The dispenser 2 comprises a housing 12 which has an openable front cover portion 13, to provide access to a dispensing mechanism inside the dispenser 2 and to permit insertion or replacement of a reservoir 21 of liquid contained within the dispenser 2, described in more detail below with reference to Figures 6 to 9. On the front of the front cover portion is a visual display 14.

The dispenser 2 is arranged to be portable and the housing 12 incorporates a handle 16 on a top portion of which is located a switch 18 which is used to commence dispensing of a liquid from the dispenser 2.

The identification device reader 11, display 14, memory device 15 and switch 18 are all connected to an electronic circuit within the dispenser 2, schematically representated by CPU 19 shown on the top portion of the handle 16. The CPU also controls a pump 27 forming part of the dispensing mechanism within the dispenser 2, which is described below with reference to figures 7a to 9.

The dispenser 2 additionally comprises a transmitter / receiver represented by symbol 20, which may form part of the electronic circuit represented by the CPU 19 or may be a separate transmitter 1 receiver within the dispenser housing 12. The transmitter/ receiver 20 can communicate with electronic devices remote from the dispenser 2, either by a local wireless network, such as Wi-Fi or other communication means such as a mobile phone, such that it may communicate with remote electronic devices either directly or via the internet, represented by cloud 7.

In the liquid dispensing system illustrated in Figure 1, the various means of communicating with the dispenser 2 are given by way of example only and it should be appreciated that various other means of communication could be used, which would enable the dispenser 2 to function in a similar manner to that described below.

The dispensing system illustrated in Figure 1 has at its core the dispenser 2. This may be used with any number of receptacles 3 to 5, only three of which have been shown in the figures. The three receptacles illustrated are all of different types, namely a small bucket 3, a large bucket 4 and a trigger bottle 5. However with such a system there could be multiple small buckets 3 which may all have tags 8 associated with them which carry the same information.

Alternatively, a plurality of receptacles of the same type, such as small buckets 3, may be categorised in some manner to divide them into different groups, whereby receptacles in a group may be of different types, for example small buckets 3, large buckets 4 and trigger bottles 5, but are associated with a common group, perhaps because they are to be used for a common task, requiring use of a particular concentrate, or a solution of a particular concentration. For example, one group of receptacles may be categorised as falling within a particular group because they are used for hospital theatre cleaning, whereas receptacles of the same type or types may be categorised in a different group, for example if they are to be used for general purpose cleaning. Alternatively the groupings could be used in some other manner as desired, for example to indicate an association with a particular user or group of users, or to indicate that they are to be used with a particular chemical concentrate to be added to the bucket by a user, with the dispenser being used to add an appropriate quantity of a further liquid, for example a liquid catalyst to activate the concentrate previously added or to be subsequently added.

The receptacles 3 to 5 may carry a visual indicator, to indicate which one of the plurality of groups they belong. For example receptacles 3 to 5 belonging to a first group may be coloured blue, whereas if they belonged to a second group they may be coloured red. Alternatively they may carry an appropriate marking, for example "Kitchen".

An identification device tag, such as RFID tag 8 associated with small bucket 3, contains data to be read by the dispenser 2, which data is associated with the small bucket 3. The identification device 8 may be associated with the small bucket 3 and programmed so it provides appropriate data to the dispenser 2. Alternatively an appropriate one of a number of pre-programmed identification devices may be selected and applied to the small bucket 3.

Continuing to consider the example of the small bucket 3 and associated identification device tag 8, the identification device tag 8 holds data relating to how much liquid from dispenser 2 is to be dispensed into the small bucket 3 and contains data identifying the receptacle type 3, (small bucket 3) and that the receptacle belongs to one particular group.

The dispenser 2 is arranged to receive pre-filled disposable pouches 21, one of which can be seen in Figure 6 inside the dispenser 2. An identification device tag 22 on the pouch 21 is arranged to be read by the identification device reader 11 on the dispenser 2, so that the dispenser 2 knows the type of chemical that is being placed in the dispenser and the CPU 19 may control the dose dispensed in dependence on the information from the identification device tag 22 associated with the disposable pouch 21.

An advantage of the dispensing system illustrated in Figure 1 is that the dispenser 2 records data from the identification devices 8 to 10 other than the volume of liquid to be dispensed. For example it may record the type of receptacle and/or any group to which that receptacle belongs. This data is provided to a system manager who, for example, may interrogate the dispenser directly, by placing a specific system manager identification device tag (not shown) adjacent to the identification device reader 11 to instruct the dispenser to display the required information on display 14 or by the dispenser transmitting the data, either periodically or upon request, to a remote device such as mobile phone 6. This enables the system manager, who may be a provider of the system, a liquid supplier or a contract manager, for example, to obtain data which will indicate what liquid is being used for and thus how often particular tasks are being performed and possibly by whom. This data can be particularly important in the management of cleaning contracts, compliance and management of resources.

An advantage of a dispenser system as illustrated in Figure 1 is that where catalyst based cleaning solutions are used, it enables different types of concentrate to be manually added to receptacles, where the receptacles are grouped to be used with specific chemicals, indicated by the colour of the receptacle. In this way an identification device, for example, identification device 8 associated with small bucket 3 indicates to the dispenser 2 that there is particular type of chemical and quantity of chemical in that small bucket 3 and this information enables the dispenser 2 to dispense an appropriate amount of a further chemical in dependence on the information received. Thus the system illustrated in Figure 1 enables concentrates of different types to receive a correct dose of catalyst, requiring only that a user place the correct type of concentrate and correct quantity of concentrate in the correct receptacle, which task may be assisted by appropriate colour coding and marking of the concentrate, or container, in addition to the colour and any markings applied to the receptacle.

Operation of the dispenser 2 will now be described with reference to Figures 2 to 5. In Figure 2 the trigger bottle 5 is shown being brought into close proximity to the dispenser 2, such that the associated identification device 10 is read by the identification device reader 11. If the identification device tag is not of an appropriate type, as in the example of Figure 2, then a dispensing action is not permitted and the display 14 indicates this. Additionally an audible warning may be provided via a speaker 15 (not shown).

Where, as shown in Figure 3, the trigger bottle 5 is of an appropriate type and group, as indicated by data on the tag 10, the display 14 indicates the quantity of liquid to be dispensed and may also indicate the type of receptacle, for example trigger bottle and the group to which the utensil belongs, in order to confirm the tag 10 matches the trigger bottle 5. Once an appropriate receptacle has been identified by the dispenser 2 and the receptacle is in the correct position, the user depresses switch 18, represented by arrow 23, and an appropriately quantity of liquid is dispensed. As previously described, with reference to Figure 1, the dispenser records the information from the identification device 10 on memory device 15 for subsequent transmission to a remote device, such as mobile device 6.

Figures 4 and 5 illustrate how different quantities may be dispensed depending on the size of receptacle 3 or 4 as identified from the associated identification device tags 8 or 9.

Referring now to Figure 6 there is shown a front view of the dispenser with the front cover portion 13 of Figure 1 removed. This reveals various components of the dispenser mounted on a base plate 24 which can be more clearly seen from Figures 7a to 7c. The components comprise the disposable pouch 21 removeably attached via connector 25 to an inlet 26 of a centrifugal pump 27. The centrifugal pump 27 pumps liquid to be dispensed from the pouch 21 through a valve assembly 28, described in more detail with reference to Figures 8 and 9. Liquid is dispensed from the valve assembly through the base plate 24 of the dispenser 2. Also mounted on the base plate 24 is a battery pack 29 which provides power to the pump 27 and the other electrical components of the dispenser.

As described below with reference to Figures 8 and 9, the valve assembly 28 in combination with the centrifugal pump 27 permits the quantity of liquid dispensed to be substantially directly proportional to the time of operation of the pump 27. The pump 27 may, in an alternative embodiment, be run at one of two or more speeds, selected in dependence on the quantity of liquid to be dispensed. Running the pump 27 at a slower speed for a low volume dispensing cycle, will result in a more accurate volume being dispensed in that cycle.

The pump 27 receives a voltage regulated supply from the battery pack 29, such that the speed of operation of the pump is substantially independent of the state of charge of the battery pack 29. This could be utilised to provide the pump 27 with multiple speed settings, if desired. The duration of the operation of the pump 27 is controlled by the CPU 19 of Figure 1. If for example a 5ml dose is to be dispensed by the dispenser 2 the CPU 19 may operate the pump 27 for an appropriate amount of time, for example one second, whereas if a 20ml dose is to be dispensed the CPU 19 may operate the pump 27 for four seconds. Liquid from the pump 27 is received by the valve assembly 28, illustrated in greater detail in Figures 8 and 9.

Figure 8 is a cross-section substantially midway through the circular body of the valve assembly 28. The valve assembly is machined (but could be moulded) out of cylindrical block 30 and has an inlet 31 for receiving liquid from the pump 27 and an outlet nozzle 32 through which liquid is dispensed.

The inlet 31 connects to a chamber 33 within the block 30. A substantially circular diaphragm 34 seals the top of the chamber 33 and the diaphragm 34 is pressed downwardly, as shown, by relatively weak spring 35 acting between the diaphragm 34 and a cover 36, which cover 36 also holds the diaphragm 34 in place via O-ring 37. Mounted to the lower surface of the diaphragm 34 is a shaft 38, a lower tip 39 of which has an O-ring 40 on it and forms a valve with outlet nozzle 32.

In Figure 8 the valve assembly 28 is shown in a closed configuration, where the spring 35 causes the tip 39 of shaft 38 to close the outlet nozzle 32. In this configuration the only residual liquid exposed to atmosphere, after a dispensing operation is any film that may remain on the lower most surface 41 of the tip 39.

An insert 42, in the bottom of the chamber 33, defines a passage 45 below the insert. This passage 45 extends down the side of the shaft 38 by virtue of the clearance between the shaft 38 and the block 30 and is sealed at its lower end, as shown in Figure 8, by the tip 39 and O-ring 40 sealing against the outlet nozzle 32. The passage 45 is fluidly connected to the chamber 33 through an accurately machined restriction 43, similar to a jet in a carburettor. The dimensions of the restriction 43 are selected dependent on the rate at which fluid is to be dispensed through the valve assembly, but the minimum cross sectional area of the passage in the restriction is ideally smaller than the minimum cross section of the outlet nozzle 32 and preferably less than half the minimum cross section of the outlet nozzle 32. A further O-ring 44 is provided around the shaft 38, so that when the valve is in the open position, as shown in Figure 9, the valve seals with the insert 42 such that fluid can only flow through the valve assembly 28 via the restriction 43.

When the centrifugal pump 27 is deactivated the valve assembly will be closed as illustrated in Figure 8. As soon as the pump 27 is activated, the pressure generated almost immediately increases the pressure in the chamber 33 causing the diaphragm 34 to raise against the resistance of the relatively weak spring 35, as shown in Figure 9, where further travel is prevented by the O-ring 44 coming into contact with the insert 42.

Due to the restriction 43, between the inlet 31 and the outlet nozzle 32, the valve assembly adopts the open position shown in Figure 9 before pressure can build at the outlet nozzle 32, avoiding any spraying or jetting of the liquid from the outlet nozzle 32 as the valve assembly is opened. Once the valve assembly is in the open configuration, illustrated in Figure 9, the pressure at the outlet nozzle 32 continues to be restricted by the presence of the restriction 43 upstream of the outlet nozzle 32, again avoiding any potentially hazardous jetting or spraying from the outlet nozzle 32.

On switching off the centrifugal pump 27 any pressure within the chamber 33 is instantly released by fluid being able to flow back through the centrifugal pump 27, thus ensuring there is no substantial pressure at the outlet nozzle 32 as the tip 39 closes the outlet nozzle 32 and thus again avoiding any potentially hazardous jetting or spraying from the outlet nozzle 32.

One example of a dispensing system has been illustrated above by way of example only. It will be appreciated that many modifications can be made to this and to the liquid dispenser and valve assembly illustrated and described therein, without departing from the scope of the invention as defined by the following claims.

Claims

1. A liquid dispensing system comprising a liquid dispenser and at least two receptacles for liquid dispensed from the liquid dispenser, each receptacle having an identifier associated with it wherein at least two of the identifiers are of different types to each other, wherein the liquid dispenser comprises a reader for the identifiers and is arranged to dispense a first volume of liquid in response to reading and identifying an identifier of a first type and to dispense a second volume of liquid, different to the first volume, in response to reading and identifying an identifier of a second type.

2. A liquid dispensing system as claimed in Claim 1, comprising a plurality of identifiers of a first type and a plurality of identifiers of a second type.

3. A liquid dispensing system as claimed in Claim 1 or 2, wherein the liquid dispenser further comprises an electronic memory arranged to receive data from the identifiers that have been read by the reader, the system further comprising means for transmitting or displaying this data.

4. A liquid dispensing system as claimed in Claim 3, wherein the liquid dispenser comprises a wireless transmitter arranged to transmit the data wirelessly.

5. A liquid dispensing system as claimed in Claim 3 or 4, wherein each type of identifier contains information other than a volume to be dispensed and the liquid dispenser records this information.

6. A liquid dispensing system as claimed in Claim 3, 4 or 5, wherein at least two types of identifier will result in the same volume of liquid being dispensed.

7. A liquid dispensing system as claimed in any preceding claim, wherein the liquid dispenser is arranged to be re-programmable to recognise different types of identifier.

8. A liquid dispensing system as claimed in any preceding claim, wherein the liquid dispenser provides an audible alarm, and/or prevents dispensing if an identifier is identified which is not of a predetermined type.

9. A liquid dispensing system as claimed in Claim 8, wherein the liquid dispenser is arranged to be reprogrammed to change the types of identifier which result in an audible alarm and/or prevent liquid being dispensed.

10. A liquid dispensing system as claimed in Claim 9, wherein a liquid to be dispensed has an identifier associated with it which is read by the reader and which reprograms the liquid dispenser to change the types of identifier which results in an audible alarm and/or prevents liquid being dispensed.

11. A liquid dispensing system as claimed in any preceding claim, wherein the identifiers are radio frequency identification device (RFID) tags and the reader is an RFID reader.

12. A liquid dispensing system as claimed in any preceding claim, comprising a plurality of receptacles, each receptacles being visually associated, by its shape, colour or marking with one of a plurality of groups of receptacles, wherein each group of receptacles is intended to have a specific purpose, wherein an identifier on each receptacle contains information relating to the group with which the receptacle is associated.

13. A liquid dispensing system as claimed in Claim 12, wherein receptacles of a group are of the same colour and different groups of receptacles are of different colours.

14. A liquid dispensing system as claimed in any preceding claim, wherein the liquid dispenser comprises an electric pump or valve which is operated for a period or at a rate determined by an identifier read by the identifier reader.

15. A liquid dispensing system as claimed in any preceding claim, wherein the liquid dispenser comprises a liquid to be dispensed and the liquid is a catalyst.

16. A liquid dispensing system as claimed in ay preceding claim, wherein the dispenser is arranged to be portable and handheld.

17. A method of dispensing a liquid from a liquid dispenser, as claimed in any preceding claim, into a receptacle, the method comprising selecting a receptacle in dependence on a type of task to be performed, placing an identifier on the receptacle that can be read by the liquid dispenser and dispensing liquid into that receptacle.

18. A method as claimed in Claim 17, comprising dispensing a catalyst from the liquid dispenser, the method comprising, in no particular order, placing a concentrate in the receptacle appropriate for the task, diluting the concentrate and dispensing from the liquid dispenser a catalyst for that concentrate into the receptacle.

19. A valve assembly comprising a housing, a diaphragm within the housing, the housing and diaphragm defining a chamber in liquid connection with a liquid inlet of the valve assembly, the valve assembly comprising biasing means for biasing the diaphragm to a first position towards the chamber, with any pressure exerted by a liquid at the liquid inlet urging the diaphragm to a second position away from the chamber, the valve assembly further comprising a nozzle at an outlet of the valve assembly and a valve located in the nozzle which valve includes a valve plug for closing the nozzle, the valve plug being connected to the diaphragm so that when the diaphragm is in the first position the valve is closed and when the diaphragm is in the second position the valve is open, the valve assembly further comprising a passage between the chamber and the nozzle through which liquid passing through the valve assembly must flow, the passage having a restriction upstream from the valve, the dimensions of the restriction being such that it defines a liquid flow path which is smaller in cross sectional area than the cross sectional area of the liquid flow path of the valve when the valve is open.

20. A valve assembly as claimed in Claim 19, wherein the cross-sectional area of the liquid flow path of the restriction is smaller than the cross-sectional areas of the liquid flow path at the valve when the valve is open.

21. A valve assembly as claimed in Claim 19 or 20, wherein the cross-sectional area of the liquid flow path at the restriction is less than 3.2 mm2.

22. A valve assembly as claimed in Claim 20, wherein the cross-sectional area of the liquid flow path at the restriction is less than 0.8 mm2.

23. A valve assembly as claimed in any one of Claims 19 to 22, wherein the biasing means is the resilience of the diaphragm.

24. A valve assembly as claimed in any one of Claims 19 to 23, wherein the valve plug is the end of a valve stem extending directly to the diaphragm.

25. A valve assembly as claimed in Claim 24, comprising a seal around the stem sealing between the stem and the chamber.

26. A liquid dispenser comprising a reservoir for a liquid, a pump, a valve assembly as claimed in any one of Claims 19 to 25 and an actuator, the pump being arranged to pump liquid from the reservoir through the valve assembly at a substantially constant pressure whereby the volume of liquid dispensed is substantially proportional to the time the pump is actuated.

27. A liquid dispenser as claimed in Claim 26, wherein the pump is a centrifugal pump.

28. A liquid dispenser as claimed in Claim 26 or 27, wherein the actuator includes a timer which controls the period of operation of the pump.

29. A liquid dispensing system as claimed in any one of Claims 1 to 16, comprising a liquid dispenser as claimed in any of Claims 25 to 27.

30. A liquid dispenser substantially as hereinbefore described with reference, and/or as illustrated in, one or more of the accompanying figures.

31. A valve assembly substantially as hereinbefore described with reference, and/or as illustrated in, one or more of the accompanying figures.