Patent Publication Number: US-2011056520-A1

Title: Method for operating a ware washer and ware washer

Description:
The invention relates to a method for operating a ware washer and to a ware washer, in particular commercial dishwasher or utensil ware washer, which is designed as a programmable machine or as a conveyor ware washer. 
     The invention is aimed particularly at a method for operating a ware washer which is designed as a programmable machine or as a conveyor ware washer and which has at least one pump, a line system connected to the pump and at least one nozzle connected to the line system, a liquid being supplied at least intermittently to the at least one nozzle via the line system while the ware washer is in operation, and the profile of the hydrostatic pressure of the liquid in the line system being detected and being compared with a predetermined pressure profile. 
     Furthermore, the invention relates to a ware washer which is designed as a programmable machine or as a conveyor ware washer and which has at least one pump, a line system connected to the pump and at least one nozzle connected to the line system, liquid being supplied at least intermittently to the at least one nozzle via the line system, and which has, furthermore, a sensor device, connected to a control device, for detecting a profile of the hydrostatic pressure of the liquid in the line system and for comparing the detected pressure profile with a predetermined pressure profile. 
     Programmable machines are manually loadable and unloadable ware washers. The programmable machines (called “box-type ware washers” or else “batch dish washers”) may be basket-type push-through ware washers, also called hood ware washers (“hood-type ware washers”), or front loaders (“front loader ware washers”). Front loaders may be built-under machines (“under counter machines”), table top machines (“top counter machines”) or free-standing ware washers with front loading (“free standing front loaders”). 
     A ware washer designed as a programmable machine usually has a treatment chamber for the cleaning of washing stock. As a rule, beneath the treatment chamber, a washing tank is arranged, in which liquid can flow out of the treatment chamber as a result of gravity. Located in the washing tank is washing liquid which is usually water, to which, if appropriate, detergent can be supplied. 
     Furthermore, a ware washer designed as a programmable machine has a washing system with a washing pump and with a line system connected to the washing pump and having washing nozzles. The washing liquid located in the washing tank can be conveyed from the washing pump to the washing nozzles via the line system and sprayed through the washing nozzles in the treatment chamber onto the washing stock to be cleaned. The sprayed washing liquid subsequently flows back into the washing tank. 
     Conveyor ware washers are, in particular, belt-type conveyor ware washers (“flight-type ware washers”) or basket-type conveyor ware washers (“rack conveyor ware washer”). Conveyor ware washers are usually employed in the commercial sector. 
     In contrast to programmable machines in which the washing stock to be cleaned remains at a fixed location in the machine during cleaning, in conveyor ware washers a transport of the washing stock through various treatment zones of the conveyor ware washer takes place. 
     A conveyor ware washer usually has at least one prewashing zone and at least one main washing zone which is arranged downstream of the prewashing zone or prewashing zones, as seen in the direction of transport of the washing stock. As a rule, at least one rewashing zone and at least one rinsing-clear zone following the rewashing zone or rewashing zones are arranged downstream of the main washing zone or main washing zones, as seen in the direction of transport. As seen in the direction of transport, either the washing stock received directly on the conveyor belt or the washing stock held by baskets usually runs in the direction of transport through an entry tunnel, the following prewashing zone or prewashing zones, main washing zone or main washing zones, rewashing zone or rewashing zones, rinsing-clear zone or rinsing-clear zones and a drying zone into an exit section. 
     Said washing zones of the conveyor ware washer are assigned in each case a washing system which has a washing pump and a line system (washing line system) which is connected to the washing pump and via which liquid is supplied to the spray nozzles of the washing zone. The washing liquid supplied to the spray nozzles is sprayed in the respective washing zone onto the washing stock which is transported by a transport device of the conveyor ware washer through the respective washing zones. Each washing zone is assigned a tank in which sprayed liquid is received and/or in which liquid for the spray nozzles of the respective zones is provided. 
     In the conveyor ware washers conventionally known from the prior art, rinsing-clear liquid in the form of fresh water, which may be pure or mixed with further additives, such as, for example, rinsing agent, is sprayed onto the washing stock via the spray nozzles of the rinsing-clear zone. At least part of the sprayed rinsing-clear liquid is transported from zone to zone, opposite to the direction of transport of the washing stock, via a cascade system. 
     The sprayed rinsing-clear liquid is captured in a tank (rewashing tank) of the rewashing zone, from which tank it is conveyed, via the washing pump of the washing system belonging to the rewashing zone, to the spray nozzles (rewashing nozzles) of the rewashing zone. Washing liquid is rinsed off from the washing stock in the rewashing zone. The liquid which in this case occurs flows into the washing tank of the at least one main washing zone which precedes the rewashing zone, as seen in the direction of transport of the washing stock. Here, the liquid is usually provided with a detergent and sprayed onto the washing stock via the nozzles (washing nozzles) of the main washing zone by means of a pump system (washing pump) belonging to the washing system of the main washing zone. In so far as no further main washing zone is provided, the liquid subsequently flows from the washing tank of the main washing zone into the prewashing tank of the prewashing zone. The liquid in the prewashing tank is sprayed onto the washing stock via the prewashing nozzles of the prewashing zone by means of a pump system belonging to the washing system of the prewashing zone, in order to remove coarse impurities from the washing stock. 
     Conventionally, ware washers are equipped with rinsing pumps which supply the line system of the rinsing-clear zone with the rinsing-clear liquid to be sprayed. This ensures, in particular, a virtually constant volume flow of the rinsing-clear liquid in the rinsing-clear zone. It is also conceivable, however, to utilize the on-site line pressure, for example the pressure of the fresh water supply, in order to deliver the rinsing-clear liquid to the line system of the rinsing-clear zone. In this last-mentioned instance, an activatable valve may be provided between the line system and the spray nozzles of the rinsing-clear zone, so that a temporary or complete interruption in the supply of rinsing-clear liquid to the spray nozzles can be achieved. 
     Irrespective of whether the ware washer is designed as a programmable machine or as a conveyor ware washer, commercial ware washers therefore usually comprise at least one pump and/or a valve which ensure/ensures a virtually constant volume flow of the washing liquid or rinsing-clear liquid for the duration of a washing or rinsing-clear process in the treatment chamber (in the case of programmable machines) or in the respective treatment zone (in the case of conveyor ware washers). The respective pumps and/or valves on the line system are switched on and off by means of a control device (machine control) belonging to the ware washer. 
     However, various operating states of the ware washer, operating errors, insufficient cleaning of the systems or an incorrect installation of washing or rinsing-clear arms (for example, after the cleaning of these) may lead to a deviation in the defined water circulation capacity or to a deviation in the desired washing pressure or desired rinsing pressure or desired nozzle pressure and, consequently, to a change in the washing performance. 
     The desired washing pressure of commercial ware washers lies in a range of approximately 0.1 to 0.8 bar, depending on the type of machine and its size. The desired rinsing-clear pressure of commercial ware washers is likewise dependent on the type and size of the machine, but usually lies in a range of 0.2 to 0.8 bar. The washing liquid volume flow in commercial built-under machines is approximately 100 to 200 l/min, and in belt-type conveyor ware washers is approximately 400 to 800 l/min. The circulated washing liquid volume flows of hood-type and basket-type conveyor ware washers are between these. In what are known as commercial “Batch Type Dishwasher” machines or programmable machines, a rinsing-clear water quantity of approximately 1.5 to 3.5 l per cycle is consumed. In continuous rinsing-clear processes, as, for example, in conveyor ware washers, the volume flow of the rinsing-clear liquid is approximately 2 to 8 l/min. 
     The publication EP 1 278 449 B1 relates to a domestic ware washer which has a washing system with an intermittently activated circulation pump and with two rotating spray arms. Furthermore, to detect a fluid pressure prevailing at the pump inlet, a sensor device is provided which is connected to a control device of the ware washer and optionally to an indicator. By the fluid pressure prevailing at the pump inlet being detected, it can be ascertained whether the spray arms of the ware washer are functioning properly. In particular, it can be ascertained whether the free rotatability of the spray arms is blocked, on account of pieces of crockery in the treatment chamber. If such an instance occurs, the intermittent operation of the circulation pump is changed correspondingly so that a predetermined washing result can be achieved. 
     The publication WO 2004/096006 A2 relates to a ware washer with a washing liquid circuit which is provided with a pressure sensor. It is possible via the pressure sensor to detect whether the hydrostatic pressure of the washing liquid circulating in the washing liquid circuit undershoots a prefixed threshold value. This occurs, for example, when a filter provided in the washing liquid circuit becomes clogged. In such an instance, there is the risk that the washing stock to be cleaned is not treated sufficiently. In order to counteract this, it is proposed to equip the ware washer with an additional washing liquid circuit which is cut in, as required, so that the washing liquid can ultimately be sprayed onto the washing stock with a predetermined desired nozzle pressure. 
     A method for operating a circulation pump in a program-controlled ware washer is known from the publication DE 197 50 266 A1. The circulation pump is activated intermittently so that pressure fluctuations can be introduced into the washing liquid in a directed manner. This is intended to promote the water flow at a screen, provided in a washing liquid circuit, with the effect of screen cleaning and dirt discharge. In order to prevent the situation where the deliberately introduced instability in the pressure profile is reduced on account of a loading of the washing liquid with foam or on account of the degree of contamination of the washing liquid, there is provision for, with the aid of a pressure sensor, detecting the pressure profile in the circulated washing liquid and, in particular, the absence of pressure fluctuations or of specific measurable pressure peaks. If such an instance occurs, an instability is caused in the pressure profile due to an abrupt reduction in the pump rotational speed. 
     The publication EP 1 008 324 A1 relates to a method for the cleaning of washing stock in a ware washer, in which washing liquid in a washing liquid circuit is sprayed onto a washing stock to be cleaned. In the washing liquid circuit, a pressure sensor is provided, via which the pressure profile of the pump pressure is detected. By means of the detected pressure profile, it is determined whether air is unintentionally sucked in by means of the circulation pump and is therefore in an unstable hydraulic state. In such an instance, the circulation pump of the ware washer is temporarily switched off or throttled. 
     The set problem on which the present invention is based is to ascertain potential deviations in the water circulation capacity or potential deviations in the nozzle pressure and automatically react correspondingly, in order to counteract the deviation in the water circulation capacity. 
     In particular, the invention is to achieve the object of providing a ware washer designed as a programmable machine or a conveyor ware washer which has a washing system with a washing pump, with a line system connected to the washing pump and with washing nozzles, potential malfunctions of the ware washer which have or may have an adverse influence on the treatment result being ascertained as early as possible. After potential malfunctions have been ascertained, countermeasures are to be automatically initiated, by means of which a deviation in the defined water circulation capacity or a change in the washing performance can be compensated as early as possible. 
     Furthermore, the object of specifying a corresponding method for operating such a ware washer is to be achieved. 
     This object is achieved, in terms of the method, by means of the subject matter of patent claim  1  and, in terms of the apparatus, by means of the subject matter of patent claim  16 . Advantageous developments of the method according to the invention are specified in the dependent patent claims  2  to  15  and of the ware washer according to the invention in the dependent patent claims  17  to  22 . 
     The solution according to the invention is distinguished in that potential deviations in the water circulation capacity or in the line pressure are detected, using suitable pressure sensors, and deviations are communicated via fault warnings to the customer or to the ware washer operator or via a remote control interface to the manufacturing company or to the competent remote maintenance system or are counteracted by means of a change of process parameters. 
     In this case, the invention is based on the recognition that, in a situation where the desired pressure in the line system is undershot immediately after a pump is switched on, this points to a leak in the line system. By contrast, a high undershooting of the desired pressure is an indication of a faulty installation of the washing or rinsing-clear arms. If the line pressure lies above the desired pressure, this is an indicator of blockages in the lines or nozzles. When a washing operation is carried out, for example in a washing zone of a conveyor ware washer, or during a washing operation in a programmable machine, furthermore, the formation of foam may occur, which can be detected by the measurement of a washing pressure which falls slowly over the duration of the washing process. 
     In particular, according to the invention, there is provision, with the aid of a pressure sensor, for detecting the profile of the hydrostatic pressure of the liquid in the line system and comparing it with a predetermined pressure profile (the ideal desired pressure profile in the fault-free operation of the machine). If there is a deviation in the detected pressure profile from the predetermined ideal pressure profile, at least one of the following steps is selected and executed automatically as a function of the type of deviation:
         i) a regulating action is carried out on the operation of the ware washer; and/or   ii) a fault warning is issued via an optical and/or acoustic interface of the ware washer; and/or   iii) a warning is issued to a remote maintenance station via a remote control interface of the ware washer.       

     The type of deviation of the detected pressure profile from the predetermined (ideal) pressure profile is determined, in particular, by the answers to the following questions:
         i) does the detected pressure profile lie below or above the ideal pressure profile?   ii) does the deviation in the detected pressure profile from the predetermined (ideal) pressure profile increase over time or does it remain constant?   iii) does the deviation occur only during continuous operation or is a deviation present even at the commencement of the operation of the ware washer?       

     In the solution according to the invention, therefore, first the type of deviation of the detected pressure profile from the predetermined (ideal) pressure profile is determined. Thus, a conclusion as to the cause of the deviation of the detected pressure profile from the predetermined (ideal) pressure profile and therefore a conclusion as to the cause of the deviation of the defined water circulation capacity in the line system or a conclusion as to the deviation of the desired pressures can be drawn. It is subsequently established whether the deviation, detected via the pressure profile, of the defined water circulation capacity may lead to a change in the washing or rinsing-clear performance of the ware washer. Should this be the case, a check is made as to whether there is a possibility of carrying out a regulating action on the operation of the ware washer, so that the potential change in the washing or rinsing-clear performance can be compensated. 
     Simultaneously with or alternatively to this, as a function of the determined cause of the deviation of the defined water circulation capacity or in the defined desired pressure, an optical and/or acoustic fault warning is issued to the machine operator, so that the latter can undertake corresponding measures. This is the case particularly when an operating error is the cause of the deviation in the defined water circulation capacity. 
     If, by contrast, it is determined that the assistance of external servicing personnel is required in order to eliminate the fault source, a corresponding fault warning is issued to a remote maintenance station automatically by the system via a remote control interface of the ware washer. This may be the case, for example, when an insufficient cleaning or rinsing-clear performance of the washing or rinsing-clear system or an incorrect installation of the washing or rinsing-clear arms or a leak in the line system is the cause of the deviation in the defined water circulation capacity or in the defined desired pressure. 
     The remote maintenance of ware washers is gaining increasing importance in the support of the hardware and software of ware washers. Due to the ever greater interlinking of the control devices of ware washers via the Internet, to the set-up of in-house intranets and to conventional telecommunication pathways (ISDN, telephone), the possibilities of direct support assistance are extended. Not least because of the possibilities for making savings in travel costs and better resource utilization (personnel and technology), remote maintenance products are used in order to lower costs in businesses. Remote maintenance programs enable the servicing engineer sitting at a distance to have direct access to the control device of the ware washer to be maintained and to carry out corresponding actions. 
    
    
     
       The invention is described in more detail below with reference to the drawings in which: 
         FIG. 1  shows diagrammatically a ware washer, designed in the form of a programmable machine, according to a preferred embodiment of the invention; 
         FIG. 2  shows diagrammatically a conveyor ware washer according to a further preferred embodiment of the invention; 
         FIG. 3  shows diagrammatically the set-up of a washing system for a conveyor ware washer according to the invention or a ware washer according to the invention designed as a programmable machine; 
         FIG. 4   a  to  f  show diagrammatic pressure profiles to explain the principle of the detection of disturbing influences with the aid of the pressure prevailing in the washing system; and 
         FIG. 5   a  to  e  show diagrammatic pressure profiles to explain the principle of the detection of disturbing influences with the aid of the pressure prevailing in the rinsing-clear system. 
     
    
    
       FIG. 1  shows a diagrammatic longitudinal sectional view of an example of a conveyor ware washer  50 . The conveyor ware washer  50  according to the illustration in  FIG. 1  has a prewashing zone  51  and a main washing zone  52  which is arranged downstream of the prewashing zone  51 , as seen in the direction of transport T of the washing stock (not illustrated in  FIG. 1 ). In the conveyor ware washer  50  illustrated in  FIG. 1 , a rewashing zone  53  and a rinsing-clear zone  54  following the rewashing zone  53  are arranged downstream of the main washing zone  52 , as seen in the direction of transport T. As seen in the direction of transport T, either washing stock received directly on the conveyor belt  58  or washing stock held by baskets runs in the direction of transport T through an entry tunnel  55 , through the following prewashing zone  51 , the main washing zone  52 , the rewashing zone  53 , the rinsing-clear zone  54  and through a drying zone  56  into an exit section  57 . 
     Said treatment zones  51 ,  52 ,  53 ,  54  of the conveyor ware washer  50  are assigned in each case spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3 ,  13 - 4 , via which liquid is sprayed onto the washing stock which is transported by the conveyor belt  58  through the respective treatment zones  51 ,  52 ,  53 ,  54 . At least each washing zone (prewashing zone  51 , main washing zone  52 , rewashing zone  53 ) is assigned a tank (washing tank  14 - 1 ,  14 - 2 ,  14 - 3 ), in which sprayed liquid is received and/or in which liquid for the spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3  of the respective zones  51 ,  52 ,  53  is provided. 
     The prewashing zone  51 , the main washing zone  52  and the rewashing zone  53  of the conveyor ware washer  50  according to the embodiment illustrated in  FIG. 1  have in each case a washing system  10 - 1 ,  10 - 2 ,  10 - 3 . Each washing system  10 - 1 ,  10 - 2 ,  10 - 3  is composed of a washing pump  11 - 1 ,  11 - 2 ,  11 - 3 , and a line system  12 - 1 ,  12 - 2 ,  12 - 3  connected to the washing pump  11 - 1 ,  11 - 2 ,  11 - 3  and of the spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3  connected to the line system  12 - 1 ,  12 - 2 ,  12 - 3 . 
     Further, a control device  20  is provided which serves (inter alia) for suitably activating the respective washing pumps  11 - 1 ,  11 - 2 ,  11 - 3  of the washing systems  10 - 1 ,  10 - 2 ,  10 - 3  during a washing process, in order at least intermittently to supply liquid via the associated line system  12 - 1 ,  12 - 2 ,  12 - 3  to the spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3  of the nozzle system belonging to the respective washing system  10 - 1 ,  10 - 2 ,  10 - 3 . 
     In particular, in the conveyor ware washer  50  illustrated in  FIG. 1 , rinsing-clear liquid in the form of fresh water, which may be mixed with further additives, such as, for example, rinsing agent, is sprayed onto the washing stock, not illustrated in  FIG. 1 , via the spray nozzles  13 - 4  of the rinsing-clear zone  54  which are arranged above and below the conveyor belt  58 . As illustrated in  FIG. 1 , laterally arranged spray nozzles  13 - 5  may also be provided in the rinsing-clear zone  54 . 
     Part of the sprayed rinsing-clear liquid is transported from zone to zone, opposite the direction of transport T of the washing stock, via a cascade system. The remaining part is conducted directly into the prewashing tank  14 - 1  via a valve  59  and a bypass line  100 . 
     The sprayed rinsing-clear liquid is captured in the tank (rewashing tank  14 - 3 ) of the rewashing zone  53 , from which tank it is conveyed to the spray nozzles  13 - 3  (rewashing nozzles) of the rewashing zone  53  via the washing pump  11 - 3  belonging to the washing system  10 - 3  of the rewashing zone  53 . Washing liquid is rinsed off from the washing stock in the rewashing zone  53 . The liquid which in this case occurs flows into the washing tank  14 - 2  of the main washing zone  52 , is usually provided with a detergent and is sprayed onto the washing stock, with the aid of a washing pump  11 - 2  belonging to the washing system  10 - 2  of the main washing zone  52 , via the spray nozzles  13 - 2  (washing nozzles) of the washing system  10 - 2  belonging to the main washing zone  52 . 
     The liquid subsequently flows from the washing tank  14 - 2  of the main washing zone  52  into the prewashing tank  14 - 1  of the prewashing zone  51 . The liquid in the prewashing tank  14 - 1  is sprayed onto the washing stock, by means of a washing pump  11 - 1  belonging to the washing system  10 - 1  of the prewashing zone  51 , via the spray nozzles  13 - 1  (prewashing nozzles) of the washing system  10 - 1  belonging to the prewashing zone  51 , in order to move coarse impurities from the washing stock. 
     Each washing system  10 - 1 ,  10 - 2 ,  10 - 3  of the conveyor ware washer  50  according to  FIG. 1  has a sensor device  30  connected to the control device  20 . The sensor devices  30  serve for detecting a profile of the hydrostatic pressure of the liquid (washing liquid) which is conveyed to the corresponding spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3  in the respective line system  12 - 1 ,  12 - 2 ,  12 - 3  of the associated washing system  10 - 1 ,  10 - 2 ,  10 - 3  with the aid of the associated washing pump  11 - 1 ,  11 - 2 ,  11 - 3 . The detected pressure profile is subsequently compared with a predetermined desired pressure profile which is filed in a storage device  21  belonging to the control device  20 . 
     In the conveyor ware washer  50  illustrated in  FIG. 1 , the control device  20  is designed, in the event of a deviation of the detected pressure profile from the predetermined pressure profile either automatically to carry out, as a function of the size and time gradient of a difference between the predetermined pressure profile and the detected pressure profile, a regulating action on the washing process proceeding in the respective treatment zone  51 ,  52 ,  53 , or to issue a fault warning via an optical and/or acoustic interface  22  or to issue a fault warning to a remote maintenance station via a remote control interface  23 . How this takes place in particular is stated later with reference to the graphs according to  FIGS. 4   a  to  4   f.    
       FIG. 2  illustrates a diagrammatic longitudinal sectional view of a ware washer  40  designed in the form of a programmable machine. The ware washer  40  designed as a programmable machine has a treatment chamber  41  for the cleaning and rinsing clear of washing stock, not illustrated in  FIG. 2 . Beneath the treatment chamber  41 , a tank  14 - 4  is arranged, in which liquid can flow back out of the treatment chamber  41  as a result of gravity. The tank  14 - 4  may be covered at the transition to the treatment chamber  41  with the aid of a screen, not illustrated in  FIG. 2 . 
     In the tank  14 - 4 , liquid is located, which is usually water, to which, if appropriate, detergent or rinsing agent can be supplied automatically in a controlled way by a detergent or rinsing agent metering device, not illustrated in  FIG. 2 . The liquid can be conveyed via a line system  12 - 5  to washing nozzles  13 - 7  by a washing pump  11 - 5  belonging to a washing system  10 - 4  of the ware washer  40  and can be sprayed through these washing nozzles  13 - 7  in the treatment chamber  41  onto the washing stock to be cleaned. The sprayed liquid subsequently flows back into the tank  14 - 4 . A discharge line  42  with a drain pump  43  may be connected to the lower end of the tank  14 - 4 , in order to empty the tank  14 - 4 , as required. 
     Like the conveyor ware washer  50  illustrated in  FIG. 1 , the ware washer  40  according to  FIG. 2 , designed as a programmable machine, has, furthermore, a control device  20 . This control device  20  serves (inter alia) for suitably activating the washing pump  11 - 5  of the washing system  10 - 4  while the ware washer is in operation, in order at least temporarily to supply liquid to the washing nozzles  13 - 7  via the line system  12 - 5 . 
     Furthermore, the washing system  10 - 4  of the ware washer  40  according to  FIG. 2 , designed as a programmable machine, has a sensor device  30  connected to the control device  20 . As in the conveyor ware washer  50  according to the illustration in  FIG. 1 , the sensor device  30  serves for detecting a profile of the hydrostatic pressure of the liquid (washing liquid) which is conveyed to the washing nozzles  13 - 7  in the line system  12 - 5  of the washing system  10 - 4  with the aid of the washing pump  11 - 5 . Likewise, in the embodiment according to  FIG. 2 , the detected pressure profile is subsequently compared with a predetermined desired pressure profile which is filed in the storage device  21  belonging to the control device  20 . 
     In functional terms, the control device  20  provided in the ware washer  40  according to  FIG. 2 , designed as a programmable machine, is identical to the control device which is used in the conveyor ware washer  50  according to  FIG. 1 . For this reason, there is no need at this juncture for a detailed description of the functioning of the control device  20 . Instead, reference is made in this regard to the following statements relating to  FIGS. 3 and 4 . 
     It remains to be stated that both the ware washer  40  according to  FIG. 2 , designed as a programmable machine, and the conveyor ware washer  50  according to  FIG. 1  in each case have at least one washing system, also designated below simply as the “washing system  10 ”, which comprises an associated washing pump (also designated below simply as the “washing pump  11 ”), an associated line system (also designated below simply as the “line system  12 ”) connected to the washing pump  11 , and also associated washing nozzles (also designated below simply as the “washing nozzles  13 ”) connected to the line system  12  and integrated in washing arms  15 - 1  and  15 - 2 . In the ware washer  40  according to  FIG. 2 , designed as a programmable machine, the washing system  10 - 4  is based on the washing pump  11 - 5 , the washing line system  12 - 5  and the washing nozzles  13 - 7 . In the conveyor ware washer  50  according to  FIG. 1 , at least the prewashing zone  51 , the main washing zone  52  and the rewashing zone  53  are provided in each case with a corresponding washing system  10 - 1 ,  10 - 2 ,  10 - 3 . These washing systems  10 - 1 ,  10 - 2 ,  10 - 3  have in each case a washing pump  11 - 1 ,  11 - 2 ,  11 - 3 , a line system  12 - 1 ,  12 - 2 ,  12 - 3  connected to the washing pump  11 - 1 ,  11 - 2 ,  11 - 3 , and spray nozzles  13 - 1 ,  13 - 2 ,  13 - 3  connected to the line system  12 - 1 ,  12 - 2 ,  12 - 3  and designated below as “washing nozzles  13 ”. 
       FIG. 3  illustrates a detailed and diagrammatic view of a preferred embodiment of a washing system  10  which may be used, for example, in the conveyor ware washer  50  illustrated in  FIG. 1  or in the ware washer  40  illustrated in  FIG. 2  and designed as a programmable machine. 
     In the washing system  10  according to  FIG. 3 , liquid (washing liquid) is routed in a circuit by a washing pump  11  from a tank  14  via a line system  12  to washing nozzles  13  which are installed in upper and lower washing arms  15 - 1 ,  15 - 2 . In a ware washer (for example, according to  FIG. 2 ) designed as a programmable machine, the washing arms  15 - 1 ,  15 - 2  having the washing nozzles  13  are arranged in the treatment chamber  41  shown in  FIG. 2 , so that the washing liquid can be conveyed out of the tank  14  via the line system  12  to the washing nozzles  13  by the washing pump  11  and sprayed through the washing nozzles  13  in the treatment chamber onto the washing stock to be cleaned (cf.  FIG. 2 ). 
     In a conveyor ware washer  50  (for example, according to  FIG. 1 ), the washing system  10  illustrated in  FIG. 3  may be provided in at least one of the respective washing zones (prewashing zone  51 , main washing zone  52 , rewashing zone  53 ). It is, of course, also conceivable not (only) to use the washing system  10  according to  FIG. 3  in one of the washing zones  51 ,  52 ,  53 , but also in the rinsing-clear zone  54  of the conveyor ware washer  50 . 
     Regardless of the question of in which of the respective treatment zones of a conveyor ware washer the washing system  10  according to the illustration in  FIG. 3  is used, in the conveyor ware washer, and also in the ware washer designed as a programmable machine, the washing liquid is sprayed through the washing tank  14  onto the washing stock via the washing nozzles  13  with the aid of the washing pump  11 . 
     In contrast to a ware washer  40  (cf.  FIG. 2 ) designed as a programmable machine, by contrast, in a conveyor ware washer the sprayed washing liquid, after being sprayed, does not, or at least does not completely, flow back into the washing tank  14  of the associated washing system  10 . Instead, as already indicated, conveyor ware washers are usually equipped with a cascade system, via which at least part of the sprayed washing liquid is transported from treatment zone to treatment zone opposite to the direction of transport T of the washing stock. The remaining part of the sprayed washing liquid may be conducted directly into the prewashing tank  14 - 1 , for example, via a valve  59  and a bypass line  100  (cf.  FIG. 1 ). 
     The washing system  10  illustrated in  FIG. 3  has at least one pressure sensor  31  which belongs to the sensor device  30  already mentioned and which is arranged either at the outlet of the washing pump  11  (cf. ref.  1 ), upstream of the washing arms  15 - 1 ,  15 - 2  in a line system  12  (cf. ref.  2 ), between two washing arms  15 - 1 ,  15 - 2  in a line system  12  (cf. ref.  3 ) or in the washing arms  15 - 1 ,  15 - 2  themselves in the immediate vicinity of the washing nozzles  13  (cf. ref.  4  and ref.  5 ). The at least one pressure sensor  31  is designed to detect the profile of the hydrostatic pressure P I  in the washing liquid. The pressure P I  to be detected by the pressure sensor  31  is built up in the line system  12  when the washing pump  11  is activated during the washing process, in order preferably to ensure a virtually constant water circulation capacity. 
     The washing pump  11  of the washing system  10  illustrated in  FIG. 3  is switched on and off via a control device  20 , illustrated in  FIG. 1  or  FIG. 2 , of the ware washer  40 ,  50  (cf.  FIGS. 1 and 2 ). Furthermore, with the aid of the control device  20 , the rotational speed of the washing pump  11  of the washing system  10  and therefore the water circulation capacity can advantageously be set. 
     As already indicated, the at least one pressure sensor  31  of the washing system  10  belongs to a sensor device  30  which is connected to the control device  20 . With the aid of the control device  20 , the profile, detected by the pressure sensor  31 , of the hydrostatic pressure P I  in the washing liquid is supplied to the control device  20 . 
       FIG. 4   a  illustrates in a diagrammatic and idealized way an “ideal” (desired) pressure profile P S  which is detected by means of the sensor device  30  and which is established in the washing system  10  during fault-free operation of the ware washer  40 ,  50 . 
     The switch-on of the washing pump  11 , for example on commencement of the washing process, takes place at a time point t 0  in the illustration according to  FIG. 4   a . This is followed by a brief “switch-on peak”, at which the actual pressure P I  detected with the aid of the at least one pressure sensor  31  of the sensor device  30  is higher than the (ideal) desired pressure P S . The desired pressure P S  is a hydrostatic pressure which is fixed for a selected operating state of the ware washer  40 ,  50  and at which the washing performance required for the operating state of the ware washer  40 ,  50  is achieved. 
     As illustrated in  FIG. 4   a , in fault-free operation of the ware washer  40 ,  50  the hydrostatic pressure P I  in the washing liquid in the washing system  10  has leveled out after the time t 1  at the desired pressure P S  fixed for the set treatment program. If the pressure detected by means of the at least one pressure sensor  31  of the sensor device  30  does not deviate from the desired pressure P S  over a time interval Δt 1 , then there are no machine-side problems. 
     The (first) time interval Δt 1  serves, in the embodiment illustrated in  FIG. 4 , as a time window for determining whether a fault-free operation of the ware washer  40 ,  50  is present or not. Within the first time interval Δt 1 , the hydrostatic pressure P I  in the washing system  10  is measured continuously with the aid of the at least one pressure sensor  31 . It is also conceivable, however, that, within the time interval Δt 1 , the hydrostatic pressure P I  is measured by predetermined time points or events, and the measured pressure values are subsequently interpolated, in order to obtain a profile of the hydrostatic pressure in the time interval Δt 1 . 
     Preferably, the time interval Δt 1  has a set length, which may be a predetermined or predeterminable (e.g., operator or service person programmable or settable) length, the start of the time interval Δt 1  being fixed by a time point t 1  at which the washing pump  11  is switched on or activated during the washing process in such a way that the washing liquid is supplied to the at least one washing nozzle  13  via the line system  12 . As illustrated in  FIG. 4   a , the start of the time interval Δt 1  lies at a time point t 1  directly behind a switch-on peak or directly after the expiry of a settling time of the pressure P I  built up in the line system  12  after the switch-on of the washing pump  11 . However, it is, of course, also conceivable to select the start of the time interval Δt 1  at another time point. 
     The ideal pressure profile P S  to be expected in fault-free operation of the ware washer  40 ,  50  is filed in the control device  20  of the ware washer  40 ,  50 , specifically preferably for each treatment program of the ware washer  40 ,  50 , if different treatment programs are provided for this and if different water circulation capacities or desired washing pressures are required for the washing processes of the respective treatment programs. It is, of course, also conceivable, however, that the ideal pressure profiles P S  to be expected in fault-free operation of the ware washer are not filed in the control device  20  itself, but in a storage device  21  connected to the control device  20 , in which case the control device  20  can have access to the storage device  21 , as required, in order to read out the pressure profile P S  ideal for the washing process to be carried out. 
     The ideal pressure profile P S  in the washing system  10  which is to be expected in fault-free operation of the ware washer  40 ,  50  is preferably filed previously in the control device  20  or storage device  21 . It is, of course, also conceivable, however, that the ideal pressure profile P S  is a pressure profile which has been detected by the sensor device  30  during an earlier washing process and filed in the control device  20  or in the storage device  21 . The advantage of this alternative is that, with the aid of the solution according to the invention, it is possible to detect whether or not a particularly slowly occurring deviation of the detected pressure profile arises in the course of time, as seen over a plurality of washing processes, and this may serve as an indicator of, for example, the degree of contamination of the washing nozzles  13  or as an indicator of the degree of contamination of a filter device provided, if appropriate, in the washing system. 
     After the pressure profile P I  detected over the time interval Δt 1  by the sensor device  30  has been supplied to the control device  20 , a comparison takes place between the detected pressure profile P I  and the ideal pressure profile P S  which is filed, for example, in the control device  20  and which is to be expected in fault-free operation of the ware washer  40 ,  50 . If a deviation of the detected pressure profile P I  from the expected pressure profile P S  arises, an analysis of the deviation takes place automatically in order to determine the cause of this and to bring about appropriate countermeasures. 
     It must be remembered, in this case, that, in determining whether a deviation from the ideal pressure profile P S  is present or not, a certain deviation range has to be taken into account. Preferably, in this case, the control device  20  should be designed in such a way that it finds a deviation from the ideal pressure profile P S  and therefore an operation of the ware washer  40 ,  50  which is not fault-free, only when the deviation of the detected pressure profile P I  from the predetermined pressure profile P S  overshoots or undershoots a predetermined or predeterminable threshold value S 0 . 
     It is, of course, also conceivable that the pressure profile P I  detected by the sensor device  30  is averaged, filtered, smoothed or otherwise processed before comparison with the predetermined (ideal) pressure profile P S . 
     In the evaluation of the detected pressure profile P I , and particularly in the comparison of the detected (and, if appropriate, processed) pressure profile P I  with the predetermined ideal pressure profile P S , it is determined whether a deviation from the ideal pressure profile P S  is present or not. However, the present invention is not restricted only to ascertaining the deviation from the ideal pressure profile P S ; on the contrary, according to the invention, there is provision, in the presence of a deviation of the detected pressure profile P I  from the predetermined pressure profile P S , for evaluating the type of deviation so that a conclusion as to the disturbing influence responsible for this deviation can be drawn. In the embodiment illustrated, the type of deviation of the detected pressure profile P I  from the ideal pressure profile P S  is to be understood as being, in particular, the size and time gradient of a difference between the predetermined pressure profile P S  (as minuend) and the detected pressure profile P I  (as subtrahend). In particular, not only is the amount of the deviation relevant, but also the question as to whether the detected pressure P I  is higher than or lower than the predetermined pressure P S , and how the time behavior of the pressure profile P I  appears. 
     It is described in detail below, with reference to the illustrations according to  FIGS. 4   a  to  4   f , how, in a preferred embodiment of the invention, a conclusion can be drawn as to different disturbing influences on the basis of the type of deviation of the detected pressure profile P I  from the ideal pressure profile P S  illustrated, for example, in  FIG. 4   a . In this case,  FIGS. 4   a  to  4   f  illustrate in a diagrammatic and idealized way pressure profiles which have been detected with the aid of the sensor device  30  in a preferred embodiment of the invention. 
     In this case, it must be remembered that, in the illustrations according to  FIGS. 4   b  to  4   d , the time interval Δt 1  (first time interval Δt 1 ) serves as a time window for detecting the actual pressure profile P I . In the case of the pressure profiles P I  illustrated, the first time interval Δt 1  commences at the time point t 1  immediately after the expiry of a settling time of the pressure built up in the line system  12  by the washing pump  11  being switched on. The end of the first time interval Δt 1  is defined by the time point t 2 . The time point t 2  is preferably selected in such a way that a sufficient number of pressure measurements can be carried out in the first time interval Δt 1  so that reliable evidence of the hydrostatic pressure P I  actually prevailing in the washing system  10  can be obtained. The time point t 2  depends, in particular, on the sensing rate achievable by the sensor device  30  or the at least one pressure sensor  31  and on the accuracy desired for the detected pressure profile P I . 
     As already indicated, the graph according to  FIG. 4   a  illustrates the pressure profile P S , such as can be expected in fault-free operation of the washing system  10 . This pressure profile P S  constitutes the ideal or predetermined pressure profile. A deviation from this arises when a fault occurs during operation, that is to say during the washing phase in the washing system  10 . In the graphs according to  FIGS. 4   b  to  4   f , the ideal desired pressure profile P S  is illustrated once again as a dashed curve profile for clearer understanding. 
     The basic pressure profile P I  illustrated in the graph according to  FIG. 4   b  is a pressure profile which is detected with the aid of the sensor device  30  when a minor leak is present in the washing system  10 . As illustrated, in the time window (first time interval Δt 1 ) taken into account, the detected pressure P I  in the washing system  10  lies slightly below the desired pressure P S . In the instance illustrated in  FIG. 4   b , that is to say when the detected pressure profile P I  lies continuously below the predetermined pressure profile within the time window (first time interval Δt 1 ) to be taken into account, and when the amount of the difference between the predetermined pressure profile P S  and the detected pressure profile P I  lies continuously within a range between a first fixed threshold value S 1  and a second fixed threshold value S 2 , a minor leak in the washing system  10  is concluded automatically with the aid of the control device  20 . In this case, a corresponding fault warning is generated automatically by the control device  20  and is issued via the optical and/or acoustic interface  22  of the ware washer  40 ,  50 , in order to draw the attention of the operator of the ware washer  40 ,  50  to the (minor) leak in the washing system  10 . 
     Alternatively or additionally to this, it is conceivable that the control device  20  also automatically generates a corresponding fault warning and communicates this directly to a remote maintenance station (remote maintenance service) via the remote control interface  23  of the ware washer  40 ,  50 . 
     As a reaction to the fault warning issued via the optical/acoustic interface  22  and/or via the remote control interface  23 , appropriate measures can then be introduced by the ware washer operator or the remote maintenance station in order to compensate the effect of the detected leak on the washing performance of the ware washer  40 ,  50 . 
     The graph according to the illustration in  FIG. 4   c  is a basic pressure profile P I  which occurs in the event of a major leak in the washing system  10  or in the event of incorrect or neglected installation of the washing arms  15 - 1 ,  15 - 2  or in the event of an absence of washing arm cleaning caps. As illustrated in  FIG. 4   c , during the time window (first time interval Δt 1 ) to be taken into account, only a relatively low pressure builds up in the washing system  10 , which lies below the second threshold value S 2  and well below the desired pressure P S  and does not approach the desired pressure P S  over the time interval Δt 1 . 
     In this case, that is to say when the detected pressure value P I  lies continuously below the predetermined pressure profile P S  and the amount of the difference between the predetermined pressure profile P S  and the detected pressure profile P I  is continuously greater than the second fixed threshold value S 2 , a major leak in the washing system  10  is concluded automatically by the control device  20  and a corresponding fault warning is issued preferably via the optical and/or acoustic interface  22  of the ware washer  40 ,  50  in order to draw the attention of the operator of the ware washer  40 ,  50  to a major leak in the washing system  10 . 
     So that a differentiation can be made as to whether the washing pressure deviation detected in the scenario according to  FIG. 4   c  is the result of a leak or the result of an incorrect installation of at least one of the washing arms  15 - 1 ,  15 - 2  or the result of the absence of washing arm cleaning caps, it is basically conceivable to provide suitable washing arm position sensors, via which corresponding warnings are issued if at least one of the washing arms  15 - 1 ,  15 - 2  is installed incorrectly or if washing arm cleaning caps are absent. In this development, a major leak in the washing system  10  is present when the detected pressure profile P I  lies continuously below the predetermined pressure profile P S  within the first time interval Δt 1  and the amount of the difference between the predetermined pressure profile P S  and the detected pressure profile P I  is continuously greater than the second fixed threshold value S 2 , and when the washing arm position sensors issue no fault warning. 
     The graph according to the illustration in  FIG. 4   d  shows in a diagrammatic and idealized way the basic pressure profile P I  which is established in the washing system  10  when one or more clogged washing nozzles  13  are present. As illustrated in  FIG. 4   d , in the event of such a fault the pressure P I  in the washing system  10  lies continuously above the desired pressure P S  during the time window Δt 1  to be taken into account. 
     In this case, that is to say when the detected pressure profile P I  lies continuously above the predetermined pressure profile P S  and the amount of the difference between the predetermined pressure profile P S  and the detected pressure profile P I  is continuously greater than a fixed threshold value S 0  characteristic of the presence of a deviation, the presence of a blockage in the washing system  10  is concluded automatically by the control device  20 . Consequently, a corresponding fault warning is issued automatically, preferably via the optical and/or acoustic interface  22 , in order to indicate to the operator of the ware washer  40 ,  50  that, for example, at least one washing nozzle  13  has to be cleaned. 
     It is conceivable, in this case, that evidence as to the degree of blockage or the number of nozzles to be cleaned can also be obtained by means of the amount of the deviation of the detected pressure profile P I  from the predetermined pressure profile P S . 
     The invention is not restricted only to evaluating the detected (actual) pressure profile P I  in the washing system  10  by means of a predetermined (ideal) pressure profile P S  at the commencement of the washing process, that is to say within the first time interval Δt 1 , so that conclusions as to possible disturbing influences can be drawn. On the contrary, the solution according to the invention also covers the detection and evaluation of the actual pressure profile P I  during a second time interval Δt 2 . The second time interval Δt 2  may lie in any desired range during the washing process. 
     In the illustrations according to  4   a  to  4   f , therefore, the pressure profile P I  is not only evaluated in the first time interval Δt 1 , which preferably lies immediately after the expiry of the settling time of the pressure built up in the line system  12  by the washing pump  11  being switched on, but also in the second time interval Δt 2 , wherein in the graphs illustrated this second time interval Δt 2  commences at the end of the first time interval Δt 1  (at the time point t 2 ) and preferably lasts as long as the washing pump  11  is running. 
     Possible pressure profiles, from which disturbances or faults occurring during the washing process become clear, are dealt with below with reference to the graphs according to the illustrations in  FIGS. 4   e  and  4   f.    
     The graph according to the illustration in  FIG. 4   e  is a basic pressure profile P I  in the event of excessive foam forming during the washing process. The graph shows that no faults have occurred during the first time interval Δt 1 . In the second time interval Δt 2 , the start of which is defined by the time point t 2  (end point of the first time interval Δt 1 ), the detected pressure P I  in the washing system  10  falls continuously at the time point t 3 . In this case, that is to say when the measured pressure P I  falls continuously within the second time interval Δt 2  from a time point t 3  lying in the time window Δt 2 , foam formation in the washing system  10  is concluded automatically, preferably after a lower threshold value is undershot. 
     In this case, an increase in the foam build-up or foam quantity during the washing process can be counteracted by a lowering of the water circulation quantity through the washing pump  11  and, along with this, of the washing pressure, so that, as a result of this measure, the ware washer  40 ,  50  continues to remain usable. In a preferred embodiment of the present invention, in the case of a detected foam build-up measured via the at least one pressure sensor  31  of the sensor device  30 , the pump capacity of the washing pump  11  is adjusted downward in proportion to the pressure drop. 
     So that a predetermined washing performance can be achieved in spite of an adjusted-down pump capacity, it is preferable that, in a conveyor ware washer  50  equipped with the special washing system  10  according to the illustration in  FIG. 3 , simultaneously with the downward adjustment of the pump capacity of the washing pump  11  the belt speed at which the washing stock to be treated is transported through the ware washer  50  is preferably reduced in proportion to the detected pressure drop. By contrast, in a ware washer  40  designed as a programmable machine, if foam formation in the washing system  10  is concluded and the pump capacity of the washing pump  11  is consequently adjusted down automatically, the program running time of the washing process should be increased, preferably in proportion to the detected pressure drop. 
     Thus, in spite of a reduction in the pump capacity and water circulation capacity, the treatment result of the ware washer  40 ,  50 , achievable at the end of a washing cycle, can be maintained. 
     Alternatively or additionally to this, it is conceivable, furthermore, that, in an instance when foam formation in the washing system  10  is concluded with the aid of the pressure profile P I  detected in the second time interval Δt 2 , a suitable defoaming agent (defoaming chemical) is added automatically to the washing liquid. Preferably, for this purpose, the ware washer  40 ,  50  has a device, activatable by the control device  20 , for adding the defoaming agent to the washing liquid. 
     The graph according to the illustration in  FIG. 4   f  shows the basic pressure profile P I  which is established when a blockage occurs in the washing system  10  during continuous washing operation (that is to say, within the second time interval Δt 2 ). This is the case, for example, when individual washing nozzles  13  become at least partially blocked during the continuous operation of the ware washer  40 ,  50 . In this case, that is to say when the measured hydrostatic pressure P I  increases continuously from a time point t 3  during the second time interval Δt 2  or during the continuous operation of the ware washer  40 ,  50 , a blockage of the washing system  10  occurring only during the continuous operation of the ware washer  40 ,  50  is concluded automatically. Consequently, a corresponding fault warning is issued automatically, preferably via the optical and/or acoustic interface  22 , in order to draw the attention of the operator of the ware washer  40 ,  50  to this disturbing factor. 
     In the above-described embodiment of the solution according to the invention, a ware washer  40 ,  50  is assumed which has at least one washing pump (washing pumps  11 - 1 ,  11 - 2 ,  11 - 3  in the conveyor ware washer  50  shown in  FIG. 1  and washing pump  11 - 5  in the ware washer  40  shown in  FIG. 2  and designed as a programmable machine) and at least one washing nozzle  13 - 1 ,  13 - 2 ,  13 - 3 ,  13 - 7  which is connected to the washing pump  11 - 1 ,  11 - 2 ,  11 - 3 ,  11 - 5  via a line system  12 - 1 ,  12 - 2 ,  12 - 3 ,  12 - 5  and to which a washing liquid is supplied during a washing process by the washing pump  11 - 1 ,  11 - 2 ,  11 - 3 ,  11 - 5  being activated, during the washing process the profile P I  of the hydrostatic pressure of the washing liquid in the line system  12 - 1 ,  12 - 2 ,  12 - 3 ,  12 - 5  being detected and being compared with a predetermined pressure profile P S . 
     Alternatively or additionally to this, however, it is also conceivable, during a rinsing-clear process, to detect the profile P I  of the hydrostatic pressure of the rinsing-clear liquid supplied to the nozzles  13 - 4 ,  13 - 5 ,  13 - 6  provided for rinsing clear and to compare it with a predetermined pressure profile P S . 
     In this case, it must be remembered that the conveyor ware washer  50  illustrated, for example, in  FIG. 1  has a rinsing-clear pump  11 - 4  and rinsing-clear nozzles  13 - 4 ,  13 - 5  connected to the rinsing-clear pump  11 - 4  via the line system  12 - 4 . During a rinsing-clear process, rinsing-clear liquid is supplied to the rinsing-clear nozzles  13 - 4 ,  13 - 5  by the rinsing-clear pump  11 - 4  being activated. In order to achieve a situation where, during the rinsing-clear process, the profile P I  of the hydrostatic pressure of the rinsing-clear liquid in the line system  12 - 4  can be detected and compared with a predetermined pressure profile P S , in the conveyor ware washer  50  illustrated in  FIG. 1  a sensor device  30 ′ is provided, having at least one pressure sensor  31 ′ which may be arranged, for example, at the outlet of the rinsing-clear pump  11 - 4  or in the line system  12 - 4  in the immediate vicinity of the rinsing-clear nozzles  13 - 4 ,  13 - 5 . The at least one pressure sensor  31 ′ is designed to detect the profile of the hydrostatic pressure P I  in the rinsing-clear liquid. The pressure P I  to be detected by the pressure sensor  31 ′ is built up in the line system  12 - 4  when the rinsing-clear pump  11 - 4  is activated during the rinsing-clear process. 
     The rinsing-clear pump  11 - 4  of the conveyor ware washer  50  illustrated in  FIG. 1  is switched on and off via the control device  20  of the ware washer  50 . Furthermore, with the aid of the control device  20 , the rotational speed of the rinsing-clear pump  11 - 4  and therefore the quantity of rinsing-clear liquid supplied per unit time for the rinsing-clear nozzles  13 - 4 ,  13 - 5  can advantageously be set. 
     On the other hand, it is, of course, also conceivable, in the ware washer  40  illustrated in  FIG. 2  and designed as a programmable machine, during a rinsing-clear process to detect the profile P I  of the hydrostatic pressure of the rinsing-clear liquid supplied to the rinsing-clear nozzles  13 - 6  provided for rinsing clear and to compare it with a predetermined pressure profile P S . In this case, it must be remembered that, in the embodiment, illustrated in  FIG. 2 , of the ware washer  40  designed as a programmable machine, a rinsing-clear pump  11 - 6  is provided which is connected with its suction side to an outlet of a water heater (boiler)  60 . The water heater  60  has an inlet connected to a fresh water supply line  61 . The fresh water supply line  61  is connectable to further fresh water supply lines  63 ,  64  via a valve  62 , so that either fresh water or fresh water with added rinse agent can be supplied to the water heater  60 . The water heater  60  has a heating system, so that the liquid (pure fresh water or fresh water with added rinse agent) supplied via the inlet can be heated in accordance with a process flow. 
     Via the rinsing-clear pump  11 - 6  connected with its suction side to the outlet of the water heater  60 , the rinsing-clear liquid optionally heated in the water heater  60  or unheated can be routed, for example during a rinsing-clear phase, to the rinsing-clear nozzles  13 - 6  via a rinsing-clear line system  12 - 6 . The rinsing-clear nozzles  13 - 6  are arranged in the treatment chamber  41 , in order to spray the rinsing-clear liquid heated in the water heater  60  onto the washing stock in the treatment chamber  41 . It is, of course, also conceivable, however, that the water heater  60  is supplied with pure fresh water, to which a rinse agent is added only after heating in the water heater  60 . 
     The solution according to the invention is not restricted to the presence of a water heater  60 . On the contrary, within the scope of the invention, the provision of a water heater  60  may even be dispensed with, so that, during a rinsing-clear process, unheated rinsing-clear liquid is conveyed to the rinsing-clear nozzles  13 - 6  arranged in the treatment chamber  41  and is sprayed onto the washing stock. 
     In the embodiment, illustrated diagrammatically in  FIG. 2 , of the ware washer  40  designed as a programmable machine, the washing nozzles  13 - 7  and the rinsing-clear nozzles  13 - 6  are in each case preferably arranged above and below the washing stock region and are directed toward the washing stock region of the treatment chamber  41 . In particular, in the embodiment illustrated, a downwardly directed upper washing nozzle system and a likewise downwardly directed upper rinsing-clear nozzle system, formed separately from this, and also an upwardly directed lower washing nozzle system and a likewise upwardly directed lower rinsing-clear nozzle system, formed separately from this, are provided. It is, of course, also conceivable, however, to provide an upper and a lower washing nozzle system which serve jointly for the spraying of washing liquid (during a washing phase) and for the spraying of rinsing-clear liquid (during a rinsing-clear phase). Also, the washing nozzles  13 - 7  and/or the rinsing-clear nozzles  13 - 6  may be arranged only at the top or only at the bottom, instead of at the bottom and top, or, instead or additionally, may also be arranged on one side of the treatment chamber  41  and be directed into the washing stock region transversely with respect to the treatment chamber  41 . 
     During a rinsing-clear process, in the embodiment, illustrated diagrammatically in  FIG. 2 , of the ware washer  40  designed as a programmable machine, rinsing-clear liquid is supplied to the rinsing-clear nozzles  13 - 6  by the rinsing-clear pump  11 - 6  being activated. In order to achieve the situation where, during the rinsing-clear process, the profile P I  of the hydrostatic pressure of the rinsing-clear liquid in the line system  12 - 6  can be detected and compared with a predetermined pressure profile P S , in the ware washer  40  illustrated in  FIG. 2  a sensor device  30 ″ is provided, having at least one pressure sensor  31 ″ which may be arranged, for example, at the outlet of the rinsing-clear pump  11 - 6  or in the line system  12 - 6  between the rinsing-clear pump  11 - 6  and the rinsing-clear nozzles  13 - 6 . The at least one pressure sensor  31 ″ is designed to detect the profile of the hydrostatic pressure P I  in the rinsing-clear liquid. The pressure P I  to be detected by the pressure sensor  31 ″ is built up in the line system  12 - 6  when the rinsing-clear pump  11 - 6  is activated during the rinsing-clear process. 
     The rinsing-clear pump  11 - 6  of the ware washer  40  illustrated in  FIG. 2  is switched on and off via the control device  20  of the ware washer  40 . Furthermore, with the aid of the control device  20 , the rotational speed of the rinsing-clear pump  11 - 6  and therefore the quantity of rinsing-clear liquid supplied per unit time to the rinsing-clear nozzles  13 - 6  can advantageously be set. 
       FIGS. 5   a  to  5   e  illustrate pressure profiles which were recorded, in the conveyor ware washer according to  FIG. 1 , with the aid of the sensor device  30 ′ or, in the ware washer  40  designed as a programmable machine, with the aid of the sensor device  30 ″ and which correspond respectively to the pressure profile of the hydrostatic pressure of the rinsing-clear liquid in the line system  12 - 4  and to the pressure profile of the hydrostatic pressure of the rinsing-clear liquid in the line system  12 - 6  during a rinsing-clear process. The pressure profiles illustrated in  FIGS. 5   a  to  5   e  for the rinsing-clear system largely correspond in profile and indication to the pressure profiles in the washing system which are explained in  FIGS. 4   a  to  4   d  and  4   f . The observations explained there for the washing system may be transferred similarly to the rinsing-clear system, and in this case the pressure profiles of the liquids in the washing system may differ from those in the rinsing-clear system, where appropriate, in their amplitudes (desired pressure P S , detected hydrostatic pressure P I , threshold values S 0 , S 1 , S 2 ). 
     The invention is not restricted to the embodiments shown by way of example in the drawings. On the contrary, the invention may be gathered from an overall consideration by a person skilled in the art of the patent claims and of the description of the exemplary embodiments. 
     Thus, it is, of course, conceivable that the start of the second time interval Δt 2  illustrated in  FIGS. 4   a  to  4   f  does not coincide with the end (time point t 2 ) of the first time interval Δt 1 . In particular, it is conceivable that the second time interval Δt 2 , like the first time interval Δt 1 , commences even immediately after the expiry of the settling time of the pressure building up in the washing system  10  when the washing pump  11  is switched on. 
     On the other hand, it is nevertheless conceivable that the profile of the hydrostatic pressure P I  is detected with the aid of the sensor device  30 ,  30 ′,  30 ″, in that the hydrostatic pressure is measured continuously during the entire washing and/or rinsing-clear process, or in that the hydrostatic pressure is measured at predetermined or predeterminable time points or events during the entire washing and/or rinsing-clear process, and the measured pressure values are interpolated. 
     The solution according to the invention makes it possible automatically to ascertain and evaluate a deviation of the pressure profile P I  prevailing in the washing system and/or rinsing-clear system from an ideal prefixed pressure profile P S , in order to record disturbances or faults which are responsible for the pressure deviation and which either are present even at the commencement of the washing process or first arise during the washing or rinsing-clear process. Suitable measures are taken automatically as a function of the type of disturbance, in order either to maintain the desired washing performance of the ware washer or, if this is not possible, to maintain the operation of the ware washer, without entailing the risk of damage occurring on the ware washer.