DE102010043845A1 - Dispensing armature for table water dispenser, has anode and cathode arranged in tap section, and power source applying direct current pulse such that irreversible membrane breakdown takes place in contamination of liquid - Google Patents

Abstract

The armature has a drain tap (11) configured such that a residue of a liquid (9) remains in a tap section of the armature during assembly of the armature after dispensing the liquid. An anode (14) and a cathode (16) are arranged in the tap section such that the anode and the cathode stay in contact with the residue of the liquid after dispensing of the liquid. A power source (18) applies a direct current pulse such that an irreversible membrane breakdown takes place in contamination of the liquid. A dispensing line (10) is provided with a dispensing channel. An independent claim is also included for a method for preventing or reducing microbial contamination of a liquid.

Description

The invention relates to a dispensing device for the dispensing of liquid with a donor channel having dispensing line, which ends in an outlet tap with end-side outlet opening, wherein the outlet tap is provided with a sterilizing device having an anode and a cathode extending into the dispensing channel and on a power source are connected.

In liquid dispensing devices with a dispensing device for removing a drinking liquid from the water supply network or a reservoir, there is the problem of nucleation in the liquid-carrying lines and, if present, the reservoir. This problem occurs especially during long periods of non-use, for example, at night or on weekends. The cause of the nucleation can be the growth of germs that have entered via the dispenser, the so-called recontamination.

From the EP 1 082 267 B1 a method for operating beverage dispensers is known in which an outlet or an outlet is temporarily dried by means of a heater. In addition, a gas can be passed through the parts to be dried, with which drinking liquid is expelled or blown out.

The DE 10 2007 055 449 A1 discloses a tap with a spout for liquid comprising a source of UV-C radiation disposed on or at or in the immediate vicinity of the outside of the spout such that the spout in the immediate area of the spout is externally exposed to re-contamination to avoid at the outlet.

The US 5,002,204 discloses a tap water operated beverage dispensing system having an outlet tap in which a pair of concentrically disposed electrodes are provided to prevent the ingress of bacteria. The area in which the electrodes are located is filled with liquid at each removal process, which remains temporarily there. A permanent DC voltage across the electrodes causes chlorine to form on the anode chlorine ions contained in the liquid, which dissolves in water to form hypochlorous acid to sterilize the liquid. At the same time, hydrogen and oxygen are produced. The resulting gas pushes the liquid out of the tap and sterilizes it. Due to the consequent outflow of the liquid, the current flow is interrupted when the electrodes are no longer in contact with the liquid (column 5, lines 24 to 32 of US 5,002,204 A ). No galvanic sterilization will take place until the next time the outlet tap is touched. Galvanic sterilization is limited to the period of time taken up by the removal of the liquid and the subsequent draining of the drain tap. Reliable protection against recontamination is thus not guaranteed. Another disadvantage is the formation of an explosive gas mixture.

The DE 601 23 645 T2 discloses a method for sterilizing a liquid in which the liquid is heated and exposed to an electric field of 10 ² V / cm to 10 ⁴ V / cm, the liquid being subjected to acoustic vibrations during application of the electric field. Due to the requirement of heating, the process is relatively energy consuming.

The object of the present invention is to specify an alternative dispensing fitting for the dispensing of liquid, in particular a drinking liquid, in which re-entrainment via an outlet opening of a dispensing tap is reliably prevented. Furthermore, a method for preventing or reducing a microbial contamination of a liquid dispenser is to be specified. In addition, a liquid donation device with a reliable anti-contamination protection is to be specified.

According to the invention the object is achieved by the subject matter of claims 1, 7 and 9. Advantageous embodiments of the invention will become apparent from the features of claims 2 to 6, 8 and 10 to 15.

According to the invention, a dispensing device is provided for dispensing liquid with a dispensing line having a dispensing channel. The dispensing line ends in an outlet tap with end outlet opening. The outlet tap has a sterilization device for preventing recontamination, wherein the sterilization device has an anode and a cathode, which extend into the dispensing channel or are arranged in the dispensing channel. The anode and the cathode are connected to a power source that can generate DC pulses. The outlet tap is designed in such a way that, when the dispensing fitting is installed according to the instructions, a remainder of the liquid remains after the dispensing of the liquid, at least in a tap section of the outlet tap. In this case, the anode and the cathode are arranged in this cock portion so that both are after the discharge of the liquid with the remaining remainder of the liquid in contact and can be acted upon by the power source with at least one DC pulse so that thereby present in the liquid germs an irreversible membrane breakthrough and thus a killing of the germs takes place.

The method used to kill the germs is commonly known by the term electroporation. The germs may be present in the liquid or may enter the liquid from the outside via the outlet opening. The peculiarity of the invention is that the outlet tap is designed so that after a dispensing a residual amount of liquid stops in a tap portion of the drain cock and does not drain through the outlet opening and this liquid forms a permanent barrier to the ingress of germs. This is achieved by keeping the electrodes in contact with the remaining liquid between two liquid discharges and sterilizing the liquid by electroporation.

The retention of the remainder of the liquid in the faucet section can be ensured, for example, by designing the faucet section such that the liquid is retained therein by capillary forces, or by arranging the faucet section in a portion of the dispensing line which rises in relation to a discharge direction of the liquid. This can easily and reliably ensure for a relatively long time that sufficient residual liquid is available to serve as a barrier to the entry of germs. At the rising line section, a sloping and idle at the end of the liquid removal line section can follow.

Uc

= Durchbruchspannung (V)

f

= Formfaktor (bei einer sphärischen Zelle: 1,5)

e

= Feldstärke V/mm

a

= Zellradius (bei einem Keim: 0,0025 mm)

cosα

ist bei senkrechter Ausrichtung 1

The field strength which must be generated by means of the DC pulse in order to reliably kill the germs by electroporation can be estimated by means of the so-called Laplace equation as follows: Uc = f × e × a × cosα

Uc

= Breakdown voltage (V)

f

= Form factor (for a spherical cell: 1.5)

e

= Field strength V / mm

a

= Cell radius (with a germ: 0.0025 mm)

cos

is in vertical orientation 1

The breakdown voltage here is the respective voltage applied to the cell membrane of the germs, which leads to an irreversible membrane breakthrough in the germs during electroporation. At 20 ° C a voltage of at least 1 V and at 4 ° C a voltage of at least 2 V has been determined. Assuming that the cell radius in a seed is about 0.0025 mm and the seed is spherical, so that the form factor can be assumed to be 1.5 and perpendicular to the electrodes, and thus cosα is equal to 1, this results in a At 4 ° C, the required breakdown voltage of 2 V is the following calculation: 2V = 1.5 × e × 0.0025 × 1 e = 2 V / (1.5 × 0.0025 mm × 1) = 533 V / mm

This means that at a field strength of 533 V / mm on a cell consisting of one cell, a voltage sufficient at 4 ° C is applied to the cell membrane in order to irreversibly break it. In a dispensing fitting according to the invention, in which an electrode spacing of 1 mm is selected, a voltage of at least 533 V should therefore be applied in order to achieve reliable destruction of the germs. The pulse should be maintained for at least 200 μs. The water of a bottled water dispenser is usually cooled to 8 ° C, so that the breakdown voltage is slightly less than 2V. Since the provision of a pulsed voltage is effected by means of a capacitor discharge and when discharging after 0.69 tau still 50% of the output voltage at the capacitor is present, must be used to achieve the breakdown voltage with a voltage about twice as large. It follows that a field strength of about 1000 V / mm should be used in order to achieve safe sterilization here. In addition, a pulse duration of 1 ms can be selected to achieve safe sterilization. In order to prevent only the recontamination, it is sufficient to apply a DC pulse to the water remaining in the tap section 1 time per minute. If the liquid flowing through is to be sterilized, 35.821 DC pulses / h or about 10 DC pulses / s would have to be applied via the electrodes at a flow rate of 120 l / h and a volume between the electrodes of 3.35 ml. However, this is associated with a high demand for electricity in comparison to a mere re-entrapment protection.

The basic advantages of electroporation are that it enables a safe killing of microorganisms in a short time (200 μs) and that it can lead to no resistance in the microorganisms. In addition, no harmful residues remain in the electroporation-treated fluid.

Conveniently, the anode and the cathode are arranged concentrically. As a result, a large electrode area can be realized at a small distance from one another, without any great resistance being placed on the outflowing liquid. The smaller the distance between the anode and the cathode, the lower the voltage with which a field strength required for germ killing can be achieved.

It has proved to be advantageous if the anode and the cathode at least in the region of the dispensing channel in each case at least superficially made of carbon, for example in the form of graphite, platinum, an electrically conductive ceramic material or other electrically conductive material, which for contact with food is suitable exist. Electrodes made of such electrically conductive material release no heavy metal ions or other toxic substances, as is often the case with certain metal electrodes. Carbon and the other materials mentioned are harmless when in contact with food. This is particularly important if the liquid is a drinking liquid, in particular drinking water or table water.

Preferably, the outlet tap has no valve. This eliminates a moving part that can wear, the dispenser more expensive and can fix in the particular difficult to remove germs. Valve-free design of the outlet tap allows greater safety with regard to preventing microbial contamination.

Outside the outlet tap, however, the dispensing line may have at least one valve. The fact that the penetration of germs is prevented by the drain cock, the risk of contamination of the valve in the dispensing channel outside the drain cock is low. However, the valve is suitable for metering the amount of outflowing liquid. It is also suitable, if necessary between two liquid withdrawals, for. Example, by evaporation, liquid loss taking place and concomitant loss of contact of one of the electrodes with the liquid at least as much liquid in the area to conduct, that both the anode and the cathode are in contact again with the liquid.

The invention further relates to a liquid dispensing device with a dispensing device according to the invention. In the liquid dispensing device, it may, for. B. to a beverage dispenser, especially a table water dispenser act. In particular, the invention also relates to a liquid dispensing device having a dispensing device according to the invention, wherein the dispensing line has at least one valve outside the outlet tap. In this case, a control device may be present, which is coupled to the sterilization device, wherein the at least one valve is electrically actuated and the control device is designed such that the at least one valve when the anode or the cathode with the rest of the liquid no longer contact is opened at such a time that enough liquid enters the tap section that both the anode and the cathode are in contact again with the liquid. As a result, for example, if the liquid dispensing device for a long time no liquid is removed and the rest of the liquid, for. B. by evaporation, as far as it decreases that the electrodes no longer have contact with the liquid, to ensure that to avoid the recontamination always a sterile liquid is present as a barrier to the ingress of germs in the liquid donation device.

The invention further relates to a method for preventing or reducing microbial contamination of a liquid dispensing device, wherein an aqueous liquid in a tap portion of a drainage tap of the liquid dispensing device is allowed to stand between two liquid withdrawals, the drainage tap having an end outlet opening. In the remaining liquid, an anode and a cathode are present, wherein the anode and the cathode are subjected to such a DC pulse that thereby occurs in existing liquid in the liquid an irreversible membrane breakthrough. The liquid may remain in the tap portion of the drain cock either by capillary forces or by the tap portion of the drain cock having a rising line portion from which the liquid can not flow out upon completion of a liquid withdrawal.

In an advantageous embodiment of the method, the outlet tap has no valve. The DC pulse may have a duration of at least 100 μs, in particular at least 200 μs, in particular at least 600 μs, in particular 1 ms. Depending on the germ, germ count and temperature, a pulse duration of 100 to 200 μs may be sufficient to kill the germs. To safely kill all germs, however, a pulse duration of 200 to 600 μs or even 200 to 1000 μs should be selected.

Preferably, the voltage of the DC pulse and the electrode spacing are selected such that an electric field builds up between the electrodes during the DC pulse whose field strength is at least 350 V / mm, in particular at least 533 V / mm, in particular at least 700 V / mm, in particular at least 1000 V / mm, is. The field strength required to kill the germs is lower the higher the temperature of the liquid. Usually the liquid is cooled at drink dispensers to 8 ° C.

Preferably, the application of the DC pulse, in particular regularly repeated. The time interval between the exposures may be 1 to 10 minutes. This can ensure that the rest of the liquid germ-free and thereby his Blocking function against germs is maintained. The time interval can start anew with each fluid withdrawal.

In a preferred embodiment, when the anode or the cathode has no contact with the liquid by means of a control device and an electrically operable valve at least as much liquid in the tap section passed that both the anode and the cathode again with the liquid in Standing in contact. This can ensure that the liquid is permanently a barrier to the entry of germs. Whether the anode and the cathode still have contact with the liquid can be determined, for example, by checking whether a current flow mediated by the ions in the liquid between the anode and the cathode can be measured. Alternatively, a liquid level can also be determined optically, for example by means of a light barrier, and the control device can be controlled as a function of the liquid level.

For carrying out the method according to the invention, the dispensing fitting according to the invention or the liquid dispensing device according to the invention can be used.

The invention will be explained in more detail with reference to drawings and exemplary embodiments. Show it:

1 a simple schematic structure of the tap section with a respective tubular anode and cathode, which are arranged concentrically to one another,

2a . 2 B schematic sectional views of an electrode assembly with two anodes and two cathodes, which are arranged concentrically to each other, from the side ( 2a ) and in supervision ( 2 B ) and

3 a schematic diagram of the DC power source for the application of a DC pulse.

At the in 1 illustrated section of a drain tap 11 a liquid gets 9 , such as bottled water, through the dispensing line 10 in the area between the anode 14 and the cathode 16 and passes this area during a fluid withdrawal. The anode 14 and the cathode 16 are tubular and arranged concentrically, wherein the distance between the anode 14 and the cathode 16 1 mm throughout. The seals 12 seal the drain tap 11 opposite the anode 14 and the cathode 16 so off that through the dispensing line 10 in the tap 11 entering liquid 9 the drain tap 11 only by passing the space between the anode 14 and the cathode 16 can leave. The insulating pieces 13 prevent direct electrical contact between the anode 14 and the cathode 16 , The insulating pieces 13 are only selectively between the anode 14 and the cathode 16 arranged so that thereby a liquid passage between the anode 14 and the cathode 16 is not prevented. After completion of the liquid withdrawal, the liquid remains 9 due to capillary forces between the anode 14 and the cathode 16 stand. The anode 14 and the cathode 16 are each via a power line 20 with the DC power source 18 connected. To carry out the method according to the invention, the anode 14 and the cathode 16 after completion of a liquid withdrawal for 1 ms via the power lines 20 with one in the DC power source 18 generated DC pulse applied to a voltage of 1000 volts. In the process, an electric field with a field strength of 1000 V / mm arises between the electrodes. This is what happens in the liquid 9 existing germs to an irreversible electroporation, so that the germs are killed. The application of the DC pulse is repeated regularly with a time interval of 1 to 10 minutes to be set. The time interval depends on the germ load of the outlet tap 11 surrounding air. The higher the germ load, the shorter the interval is chosen.

2a shows a lateral cross section through an electrode assembly with a dispensing device not shown here. The tubular anodes 14 are here together with a tubular cathode 16 concentric around a central cathode 16 arranged. The anodes 14 and the cathodes 16 are each by insulating pieces 13 separated from each other. The distance between the anodes 14 and the cathodes 16 is 1 mm each. The liquid to be taken from the dispensing fitting 9 flows through the space between the anodes 14 and the cathodes 16 , Upon completion of the liquid withdrawal, liquid will remain due to capillary forces 9 between the anodes 14 and the cathodes 16 stand.

2 B shows a cross section through the electrode assembly according to 2a along the line AA in 2a ,

3 shows a schematic diagram of the DC power source for the application of a DC pulse. The reference numerals in 3 as far as they are identified by the reference numbers in 1 and 2a and 2 B are identical, the same meaning as in these figures. The high voltage generation unit 24 generates a 1000 V DC voltage from a 12 V DC voltage, which is buffered by means of a capacitor. from Capacitor, a 1000 V DC pulse is passed to the electrodes as soon as the current pulse switch 26 this allows. The current pulse switch 26 receives the signal for triggering the pulse from the timing relay 28 , About this time relay, the pulse duration and the time interval in which the electrodes are supplied with the DC pulse can be controlled.

About the electricity indicator 30 is always measured whether between the electrodes still a through the liquid in between 9 effected current flow takes place. As soon as this is no longer the case, is via the operational amplifier shown schematically 31 the refill solenoid valve 32 open at such a time that enough liquid flows in that both the anode 14 as well as the cathode 16 again in contact with the liquid and thereby a current flow between the electrodes can be measured.

LIST OF REFERENCE NUMBERS

9

liquid

10

dispensing line

11

drain cock

12

poetry

13

Insulating

14

anode

16

cathode

18

DC power source

20

power line

22

ground potential

24

High voltage generating unit

26

Current pulse switch

28

time Relays

30

power indicator

31

operational amplifiers

32

Nachfüllmagnetventil

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1082267 B1 [0003]
• DE 102007055449 A1 [0004]
• US 5002204 [0005]
• US 5002204 A [0005]
• DE 60123645 T2 [0006]

Claims (15)

Dispensing fitting for dispensing liquid 9 with a dispensing duct having a dispensing duct 10 that in an outlet tap 11 ends with end-side outlet opening, wherein the outlet tap 11 a sterilization device for preventing recontamination, which is an anode 14 and a cathode 16 which extend into the dispensing channel or are arranged in the dispensing channel and to a power source 18 , which can generate DC pulses, are connected, with the tap 11 is designed such that when properly assembled the dispensing device after the delivery of the liquid 9 a residue of the liquid 9 at least in a tap section of the tap 11 remains behind, with the anode 14 and the cathode 16 in this tap section are arranged so that both after the discharge of the liquid 9 with the remainder of the liquid remaining 9 be in contact and through the power source 18 With at least one DC pulse can be applied so that thereby in the liquid 9 existing germs an irreversible membrane breakthrough takes place. Dispensing fitting according to claim 1, wherein the anode 14 and the cathode 16 are arranged concentrically. Dispensing fitting according to one of the preceding claims, wherein the anode 14 and the cathode 16 at least in the region of the dispensing channel in each case at least superficially made of carbon, platinum, an electrically conductive ceramic material or any other electrically conductive material which is suitable for contact with food. Dispensing fitting according to one of the preceding claims, wherein the tap portion is designed so that the liquid 9 is retained therein by capillary forces or wherein the tap portion in a with respect to a discharge direction of the liquid 9 rising section of the donation line 10 is arranged. Dispensing fitting according to one of the preceding claims, wherein the outlet tap 11 has no valve. Dispensing fitting according to one of the preceding claims, wherein the dispensing line 10 outside the drain tap 11 has at least one valve. Liquid dispensing device with a dispensing device according to one of the preceding claims. A liquid dispensing device with a dispensing device according to claim 6, wherein a control device is present, which is coupled to the sterilization device, wherein the at least one valve is electrically actuated, wherein the control device is designed such that the at least one valve when the anode 14 or the cathode 16 with the rest of the liquid 9 no longer having contact, open at such a time that enough liquid 9 gets into the tap section that both the anode 14 as well as the cathode 16 again with the liquid 9 stay in contact. A method of preventing or reducing microbial contamination of a liquid dispenser, wherein an aqueous liquid 9 in a tap section of a drain tap 11 the liquid dispensing device stops between two liquid withdrawals, wherein the outlet tap 11 having an end outlet opening, wherein in the standing liquid 9 an anode 14 and a cathode 16 are present, the anode 14 and the cathode 16 be subjected to such a DC pulse that thereby in in the liquid 9 existing germs an irreversible membrane breakthrough takes place. The method of claim 9, wherein the drain cock 11 has no valve. Method according to claim 9 or 10, wherein the DC pulse has a duration of at least 100 μs, in particular at least 200 μs, in particular at least 600 μs, in particular 1 ms. Method according to one of claims 9 to 11, wherein the voltage of the DC pulse and the electrode spacing are selected so that an electric field builds up during the DC pulse between the electrodes, the field strength of at least 350 V / mm, in particular at least 533 V / mm, in particular at least 700 V / mm, in particular at least 1000 V / mm. Method according to one of claims 9 to 12, wherein the application of the DC pulse, in particular regularly, in particular with an intermediate time interval of 1 to 10 minutes, is repeated. Method according to one of claims 9 to 13, wherein when the anode 14 or the cathode 16 no more contact with the liquid 9 has at least as much liquid by means of a control device and an electrically operable valve 9 passed into the tap section that both the anode 14 as well as the cathode 16 again with the liquid 9 stay in contact. Method according to one of claims 9 to 14, wherein for performing the method, a dispensing device according to one of claims 1 to 6 or a liquid dispensing device according to claim 7 or 8 is used.

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