IE20050565A1 - Warewashing system - Google Patents

Abstract

A warewashing machine (1) has a water tank (9) connected to a water inlet (13). A water level switch (17) is adapted to operate when a water level within the tank means is below a predetermined level at which sufficient water is present to carry out a predetermined cycle of operation of the machine such as a rinse cycle. <Figure 2>

Description

WAREWASHING SYSTEM The present invention relates to a system for washing glassware and the like, for example in a licensed Or catering establishment. More particularly but not exclusively, it relates to apparatus for washing glassware and the like that is suitable for use where water supplies may be unreliable.

In establishments such as pubs, clubs, bars, restaurants, cafes, hotels and the like, it is important to wash glassware, kitchenware, crockery, cutlery and so forth rapidly and effectively. Not only is this extremely important on hygiene grounds, but a pint of beer, for example, served in a glass with trace surface contamination, may be unable to form a head or may lose its head very rapidly. The very demanding combination required of speed, volume to be cleaned and thoroughness of washing has led to commercial “warewashing” machines differing significantly from domestic dishwashing machines (a typical cycle time for a warewasher may be only one or two minutes per load, for example, compared to a domestic machine where the cycle time may be 20 to 40 minutes).

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/)AU )^//4 - £ Ο 5 Ο 5 6 5 A typical glasswasher will begin operation with a charge of wash water of perhaps twenty litres. In conventional practice, at least in the UK and Eire, this is heated to around 55°C, a specially-selected detergent is added, and a load of glassware, etc, is washed thoroughly therewith, taking perhaps two minutes. There is then a final rinse with a fresh charge of water, heated to around 65°C. The rinse takes perhaps ten seconds, and typically uses a further three and a half litres of water. This substantially clean rinse water displaces an equivalent volume of the wash water charge from the machine. There is often a weir arrangement in a warewashing machine so that the wash water displaced is from an upper layer of a pool. A substantial proportion of the particulate matter cleansed from the glassware and held in suspension by the detergent will be present in this upper layer, so the remaining water held for the next wash cycle will be relatively clean or refreshed. The warewashing machine can thus run for many consecutive cycles, only needing to be supplied with a three-and-a-half litre charge of rinse water for each cycle, and an appropriate detergent charge.

Unfortunately, this may lead to problems when the mains water supply is unreliable. In certain regions, the spread of housing and consequent demand for water has outgrown the infrastructure for providing fresh water. When usage has been high, for example by late in the evening, the mains water supply can be low in pressure, arrive at a low flow rate, or fail entirely. For example, it is not uncommon in these regions for buckets of water to be kept for flushing toilets when the mains water supply is too low to refill the corresponding cisterns. Ο 5 Ο 5 6 5 Thus, a warewashing machine that has been operating as described for part of an evening may attempt to draw a charge of rinse water, but fail. It will continue regardless, leaving glassware unrinsed and with surface deposits of detergent. The wash water will also not be refreshed. The glasses with detergent present will look clean but bubble formation and head retention will be inferior. This poor “presentation” may lead to an otherwise satisfactory pint being returned to the bar. Some drinkers would even detect taint from low levels of unrinsed detergent on the glass.

Worse, over successive cycles, contamination may build up in the unrefreshed wash water and the glassware may not be washed hygienically.

As a result, a reluctance to use detergents has arisen where rinse water supplies cannot be guaranteed. However, without a detergent, it is difficult to clean ware effectively; while glasswasher detergents also act as sterilants at 55°C or so, plain water must be heated above 96°C to sterilise the ware, which must be exposed to these conditions for at least two minutes. Many deposits on the ware will not be effectively removed by hot water alone. The contamination that is removed would not be held in suspension by the detergent, ensuring that it is led off to drain, but can accumulate in deposits within the warewashing machine. This requires frequent scouring of the warewasher with aggressive cleaning agents to prevent it becoming a source of contamination.

Although these problems might appear worse than those resulting from unrinsed detergent, nevertheless many publicans will not use detergents where they believe that •E 3 5 Ο 5 6 5 they cannot rely on a rinse water supply. In newly-built premises, large extra water tanks may be installed, but the cost penalties are high, and for existing premises have usually been found to be prohibitive; the cost of installing conventional piping between the tanks and the warewasher(s) and redecorating afterwards is often particularly high.

While it might be possible to redesign warewashing machines to overcome such problems, the market is unlikely to be large enough to justify such development, and licensees or publicans would in any case probably be unwilling to replace existing machines which are otherwise in perfect working order.

It is hence an object of the present invention to provide a warewashing system that θ obviates the above disadvantages, allowing a user to wash ware effectively, using detergents, fully confident that thorough rinsing will take place.

According to a first aspect of the present invention, there is provided a warewashing machine as hereindefined comprising water tank means connected to water inlet means of the machine and provided with water level switch means adapted to operate when a water level within the tank means is below a predetermined level at which sufficient water is present to carry out a predetermined cycle of operation of the machine.

Said cycle of operation may comprise a rinse cycle. ^ 0 5 05 6 5 Preferably, the water level switch means is operatively connected to indicator means, such as illuminable warning means.

Advantageously, the water tank means is fillable from a mains water supply.

The water tank means may be disposed externally of a main casing of the machine.

The water tank means may be provided with pump means operable to transfer water therefrom into the machine.

Control means may be provided, so adapted as to open water inlet means of the machine and operate the pump means simultaneously.

In a preferred embodiment of the invention, the water level switch means is so operatively connected to control means of the machine as to halt operation thereof when the water level in the tank is below said predetermined level.

Advantageously, the control means is adapted so to halt operation of the machine after a predetermined delay period.

Optionally, said delay period may be longer than a duration of said predetermined cycle of the machine. ^ 0 5 05 65 The machine may thus complete a cycle that is in progress before its operation is halted.

Preferably, the control means comprises door safety circuit means operatively connected to door switch means mounted to a door of the machine and adapted to prevent operation of the machine when the door switch means indicates that the door is open.

Advantageously, the water level switch means is operatively connected to said door safety circuit means.

The machine may thus be operable solely when the water level is at or above said predetermined level and the door is closed.

According to a second aspect of the present invention, there is provided a method of 10 warewashing comprising the steps of providing a warewashing machine as herein defined, providing water tank means connected to an inlet means of the machine and provided with water level switch means adapted to operate when a water level within the tank means is below a predetermined level at which sufficient water is present to carry out a predetermined cycle of operation of the machine, and operating the warewashing machine using water supplied from the water tank means.

Preferably, said cycle comprises a rinse cycle of the machine.

IE 0 5 05 65 Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a schematic cross-sectional elevation of an existing warewashing machine; Figure 2 is a perspective view of a warewashing machine provided with a reservoir tank embodying a first aspect of the present invention; Figure 3 is a schematic cross-sectional elevation of the reservoir tank shown in Figure 2; Figure 4 is a circuit diagram for a first control circuit for the warewashing machine and reservoir tank shown in Figure 2; and Figure 5 is a circuit diagram for a second control circuit therefor.

Referring now to the figures and to Figure 1 in particular, an existing warewashing machine I comprises an internal chamber 2 into which racks or trays, carrying glassware, crockery or other ware to be washed, are placed (not shown). An array 3 of pipes extends around the chamber 2, the pipes being apertured such that water pumped therethrough will emerge as jets or sprays 4 directed on to the ware to be washed.

Conventionally, mains or tank-supplied water is taken in through an inlet 5 controlled by a solenoid, heated to a working temperature and dosed with a predetermined quantity of a preselected detergent. A typical charge of water to fill an average sized front loading glass or dish washing machine comprises about twenty litres. This water is pumped ¢ 0 5 05 6 5 through the array 3 of pipes, is sprayed on to the ware in the chamber 2 and collects in a sump 6, from which it is pumped back through the array 3 of pipes on to the ware, and so forth. A warewashing machine 1 for use in a bar will typically take around two minutes to clean a full load of glasses, etc, in this manner.

Once the above wash cycle is complete, a fresh charge of mains water is taken in (typically around three and a half litres) and heated to a working temperature, optionally with the addition of a rinse-aid. This water is sprayed through the array 3 of pipes on to the ware, to rinse off detergent residues. The rinse cycle usually lasts ten to fifteen seconds.

This rinse water also collects in the sump 6. However, the sump 6 has a weir outlet 7 which is arranged so that water in excess of the standard charge of water needed for a wash cycle flows out to drain. The wash water in an upper portion 8 of the sump 6 will contain a high proportion of any contaminants, especially particulates, that have been washed off the ware, and suspended in micellar form by the detergent. Thus, when the rinse water reaches the sump 6, this more polluted portion of the wash water will be preferentially displaced through the outlet 7. The remaining wash water mixes with the rinse water, to form the wash water for the next wash cycle of the machine. Once the machine 1 has been filled, it can, for example, run throughout an evening’s business, only needing to take in a charge of rinse water every cycle.

IE Ο 5 Ο 5 6 5 However, if the mains or tank water supply begins to run low, the machine 1 will not be able to take in sufficient rinse water to perform a thorough rinse, and eventually may be unable to take in any more water at all. The ware will emerge from the machine 1 with detergent residues present, potentially affecting the presentation and taste of beverages served therein. Also, the same charge of wash water will be used cycle after cycle without being refreshed, becoming increasingly dirty and washing less and less effectively. There will be no indication that these problems have arisen until customer complaints arise, when it is too late to correct, or to delay washing until the water supply is restored.

The warewashing machine 1 shown in Figure 2 has been provided with a reservoir tank 9 in order to overcome the above problems. The reservoir tank 9 and its associated pump 10 may conveniently be located adjacent the warewashing machine I, for example under a bench or table used for storing clean or dirty glassware.

As shown in Figure 3, the reservoir tank 9 contains a main volume of water 11 together with a reserve volume of water 12 in a restricted lower portion thereof. An inlet valve 13 is connected to the mains water supply, and is controlled by a conventional ballcock system 14 to prevent the tank 9 overfilling. An outlet 15 of the tank 9 is located adjacent a lowest portion thereof, and leads to the pump 10 which is operable to deliver water from the tank 9, along a connecting pipe 16, to the inlet 5 of the warewashing machine 1, which is no longer directly connected to the mains water supply. A water level switch 17 is located immediately above the reserve volume of water 12. ιέ Ο 5 Ο 5 6 5 With a normal constant mains water flow, the tank 9 will fill to a first level 18, at which the main volume of water 11 could typically comprise about sixty litres, depending on its size and shape, but sufficient for an initial charge of wash water and a large number of charges of rinse Water. As soon as water is extracted through the outlet 15 by the pump , the tank 9 will be replenished through the inlet valve 13. The water level switch 17 would not be activated unless the water level fell to a second level 19, at which only the reserve volume of water 12 remains. (The reserve volume 12 could be about four litres). This should only occur if the mains water supply has become feeble or stopped altogether.

Additional control circuits are fitted to the warewashing machine 1 and connected to the water level switch 17 of the tank 9 and the pump 10, to regulate operation of the machine 1 in such circumstances. A first control circuit for an electrically-controlled warewashing machine 1 is shown in Figure 4, and a second control circuit for an electronicallycontrolled warewashing machine 1 is shown in Figure 5.

In the first control circuit, shown in Figure 4, element Ml, which controls the pump 10 of the reservoir tank 9, is joined to the solenoid controlling the inlet 5 of the warewashing machine 1 by connection MS. An existing wash cycle lamp LI (lamp 21 in Figure 2) is linked by connection MT to an existing timer 20 of the warewashing machine 1 (see Figure 2), which regulates its washing and rinsing cycles. A first level switch SI corresponds to the water level switch 17 of the reservoir tank 9. An existing door safety switch S2 is physically connected to a door 22 of the machine (see Figure 2) and is /£ 0 5 05 6 5 operatively linked to an existing safety circuit by means of connection MD; the safety circuit prevents operation of the machine 1 while the door 22 is open. A low water warning lamp L2 (lamp 23 in Figure 2) is linked to the level switch SI. A first relay Cl is connected in parallel with the wash cycle lamp LI and in series with the level switch SI and the low water warning lamp L2. A second timed relay C2 is connected in series with the level switch S1 and separately in series with the door safety switch S2.

In normal operation, whenever the machine 1 requires water, the solenoid on the water inlet 5 opens and the element Ml turns on the pump 10 to transfer water from the tank 9 to the machine I. While a wash or rinse cycle is in progress, the wash cycle lamp LI is on, as for an unmodified machine 1. While the water level in the tank 9 remains above the water level switch 17, level switch SI remains open and no power reaches the low water warning lamp L2 or the timed relay C2.

However, the circuit operates in a novel fashion should a wash cycle begin with sufficient water in the tank 9 to carry out one rinse cycle, but insufficient for two rinse cycles. The machine 1 operates as normal until the solenoid and the pump 10 are operating to transfer water from the tank 9 for the rinse cycle. When the water level in the tank 9 falls below the water level switch 17, level switch S1 closes, completing the circuit to the timed relay C2. The timed relay C2 operates after a predetermined delay, breaking the door safety circuit and halting operation of the machine 1 just as if the door 22 were open and the door safety switch S2 had broken the circuit. The delay of the timed relay C2 is normally set to around fifteen seconds, giving sufficient time for the current rinse cycle to be £ 0 5 05 6 5 completed, after switch S1 closes but before the door safety circuit halts the machine 1. The position of the water level switch 17 in the tank 9 ensures that at this point there is always a reserve volume 12 of water remaining in the tank 9 sufficient to complete the rinse cycle.

While the rinse cycle is still running, power is supplied to the wash cycle lamp LI, and hence also to the first relay Cl. This operates to break the circuit linked to the low water warning lamp L2. At the end of a cycle, relay Cl closes. Thus, although the level switch SI closes as soon as the water level in the tank 9 becomes critical, the circuit to the low water warning lamp L2 is only completed once the current rinse cycle is complete.

An operator will thus find the machine 1 at the end of a wash and rinse cycle, containing a fully-washed and rinsed load, but with the low water warning lamp L2 lit, warning that there is now insufficient water in the tank 9 for another cycle.

If the operator nevertheless attempts to run the machine 1 immediately, the level switch SI will still be closed, energising the relay C2 which keeps the door safety circuit broken.

Thus, the machine 1 cannot be started with insufficient water in the tank 9 to complete the rinse cycle. If the mains water supply then manages to refill the tank 9 to a level above the water level switch 17, and so there is a sufficient reserve volume 12 of water present to carry out a rinse cycle, the level switch SI will open once more. The relay C2 is de-energi$ed, releasing the door safety circuit so that the machine 1 will now run. The wash and rinse cycle then continues as described above.

If the operator instead leaves the machine 1 unused, and the tank 9 refills as described above, the level switch SI will open, the relay C2 will release the door safety circuit, and the machine 1 will be ready for use when required. Also, as soon as the level switch SI opens, the circuit to the low water warning lamp L2 is broken, the extinguished lamp 23 thus alerting the operator that the machine 1 is back on line.

The machine is thus prevented from operating only so long as there is insufficient water available to carry out an effective wash and rinse cycle, but no longer.

One example of a control circuit, as shown in Figure 4, is also of benefit should a further problem, occasionally encountered with warewashing machines, arise. A warewashing 1° machine is normally adapted to take in water until an internal pressure switch detects that sufficient is present, at which point the solenoid closes the inlet 5. However, during a first wash cycle with a hitherto empty machine, the array 3 of pipes extending around the chamber 2 must be primed with water before they can begin to spray the ware in the chamber 2. The displacement of water into the array 3 of pipes causes a brief drop in pressure, as measured by the internal pressure switch, and the warewasher 1 may attempt to take in another charge of wash water on top of that already present. This can cause problems with the operation of the warewasher.

If the tank 9 is dimensioned to hold just enough water for an initial charge (around twenty litres) plus one rinse cycle (i.e. a reserve volume of around four litres) plus a small safety margin, the initial charge will bring the water level close to the water level switch 17.

IE 0 5 0 5 6 5 Thus, if the warewashing machine 1 attempts to take in a top-up to the initial charge, as described above, it will soon cause the level switch SI to close, halting the machine 1 and illuminating the low water warning lamp L2 to indicate a problem. The delay on the timed relay C2 may allow much of the reserve volume 12 to be transferred into the machine 1 before it is halted, but the control circuit will prevent further operation of the machine 1 until the tank 9 has refilled with enough water to perform the rinse cycle. By this stage, the transient change in internal pressure within the machine 1, which caused the problem in the first place, will have passed, and the machine 1 will operate as normal.

It is also possible that the machine 1 may attempt to take in an initial charge of wash water (i.e. perhaps twenty litres) when the tank 9 holds less than this volume. The level switch S1 will thus close part-way though the fill. The delay on the timed relay C2 will allow the reserve volume 12 to be transferred to the machine 1, but the machine will then be “frozen” until the level of water in the tank 9 rises above the water level switch 17 once more. If the fill is still incomplete, this sequence may be repeated. Thus, if a machine 1 is started up when the water supply is already low, the control circuit will operate first to fill up the machine 1 stepwise with the required initial charge of wash water, then to provide a reserve in the tank 9 sufficient to carry out the rinse cycle, and only then will it allow the machine to start out a wash.

Thus, the maximum possible benefit can be gained from a weak or intermittent water supply, without ever risking running a warewashing machine with insufficient water to give a good result. £ Ο 5 Ο 5 6 5 The first control circuit, shown in Figure 4, is suitable for use with conventionally electrically-controlled warewashing machines, in which it is possible to connect the control circuit shown into the existing control circuitry at the points indicated. However, some warewashing machines have their entire control circuitry on a single electronic chip, or even simulated by software, making physical links to selected points in the circuitry difficult or impossible. In such cases, an alternative, second control circuit as shown in Figure 5 is more appropriate; the reservoir tank 9 remains the same in each case.

In the second control circuit, a relay Cl. is connected in series with the solenoid for the inlet 5 of the warewashing machine 1 through connection MS. When the solenoid is activated to take water into the machine 1, the relay Cl operates to complete a circuit to the element MJ, which controls the pump 10 of the reservoir tank 9. Thus, whenever there is a demand from the machine 1, the pump 10 operates to supply it.

The level switch SI is connected in series with a low water warning lamp L2 (lamp 23 in Figure 2). Thus, when the water level in the reservoir tank 9 falls below the water level switch 17 therein, the switch SI closes, illuminating the low water warning lamp L2, to warn the operator that the water level is too low.

Although there are no interlocks to prevent machine operation with a low water supply, if the low water warning lamp L2 is off at the start of a wash, then the operator may assume that there is sufficient water in the tank 9 to carry out the rinse cycle, and may start the ^3 5 05 6 5 wash. If the lamp L2 comes on during the rinse cycle, then the operator knows that there still remains the reserve volume 12, sufficient to complete the rinse. If the operator wishes to start a wash, but the lamp L2 is on, he knows that the tank 9 will run dry during the rinse cycle, and he should not start the machine until enough water has accumulated in the reservoir tank 9 for a complete rinse cycle (at which point, the lamp L2 goes out again). Although this variation requires the operator to be trained to heed the low water warning lamp 23, it is still far superior to starting a wash and hoping that there will be enough water in the mains when the rinse cycle is due.

Claims (15)

1. A warewashing machine, as defined herein, comprising water inlet means to the machine, water tank means connected thereto and water level switch means adapted to operate when a water level within the tank means is below a 5 predetermined level at which there is sufficient water present to carry out a predetermined cycle of operation of the machine.

2. A machine as claimed in claim 1, wherein said cycle of operation comprises a rinse cycle.

3. A machine as claimed in either claim 1 or claim 2, wherein the water level switch 10 means is operatively connected to indicator means, such as illuminable warning means.

4. A machine as claimed in any one of the preceding claims, wherein the water tank means is fillable from a mains water supply.

5. A machine as claimed in any one of the preceding claim, wherein the water tank 15 means may be disposed externally of a main casing of the machine.

6. A machine as claimed in any one of the preceding claims, wherein the water tank means is provided with pump means operable to transfer water therefrom into the machine. Ζ 5 Ο 5 6 5

7. A machine as claimed in claim 6, further comprising control means adapted to open the water inlet means of the machine and operate the pump means simultaneously.

8. A machine as claimed in claim 7, wherein the water level switch means is so 5 operatively connected to the control means as to halt operation of the machine when the water level in the tank is below said predetermined level.

9. A machine as claimed in either cjaim 7 or claim 8, wherein the control means is adapted to halt operation of the machine after a predetermined delay period.

10. A machine as claimed on any one of claims 7 to 9, wherein the control means 10 further comprises door safety circuit means operatively connected to door switch means mounted to a door of the machine and adapted to prevent operation of the machine when the door switch means indicates that the door is open.

11. A machine as claimed in claim 10, wherein the water level switch means is operatively connected to said door safety circuit means. 15

12. A method of warewashing comprising the steps of providing a warewashing machine as herein defined, providing water tank means connected to an inlet means of the machine, providing water level switch means adapted to operate when a water level within the tank means is below a predetermined level at which /£0 5 0 5 6 5 sufficient water is present to carry out a predetermined cycle of operation of the machine, and operating the warewashing machine using water supplied from the water tank means.

13. A method as claimed in Claim 12, wherein said cycle comprises a rinse of cycle of 5 the machine.

14. A warewashing machine as claimed in Claim 1, substantially as herein described with reference to and/or as shown in Figures 2 to 5 of the accompanying drawings.

15. A method of warewashing as claimed in Claim 12, substantially as herein described with reference to Figures 2 to 5 of the accompanying drawings.