Method for producing a medical preparation using a peristaltic pump

Abstract

The invention relates to a method and a system for synthesizing a medical preparation, a peristaltic pump being used for pumping liquid from a plurality of source containers. According to the invention, micro-amounts are extracted only in the linear region of the peristaltic pump.

Claims

1. A method for producing a medical preparation, in particular for parenteral nutrition, the method comprising: transferring liquids by a peristaltic pump from a plurality of source containers into a target container, wherein the peristaltic pump has at least one region with a linear characteristic curve and one region with a non-linear characteristic curve of the pump output, and metering from at least one source container by bringing the peristaltic pump to a position such that the metering from the at least one source container takes place entirely in the region with the linear characteristic curve of the pump output.

2. The method for producing a medical preparation as claimed in claim 1, wherein the peristaltic pump is brought to a position in which the suction-side characteristic curve of the peristaltic pump is linear.

3. The method for producing a medical preparation as claimed in claim 1, wherein, in order to bring the peristaltic pump to the desired position with a linear characteristic curve, liquid is removed from another source container than the one from which metering is intended to take place, the other source container being from a source container with universal liquid or water.

4. The method for producing a medical preparation as claimed in claim 1, wherein a very small quantity with a volume of under 10 ml is delivered in the region of the linear characteristic curve.

5. The method for producing a medical preparation as claimed in claim 4, wherein the volume is under 5 ml.

6. The method for producing a medical preparation as claimed in claim 1, wherein precisely one single peristaltic pump is used for transferring the liquids from all of the source containers into the target container.

7. The method for producing a medical preparation as claimed in claim 1, wherein, in at least one further metering step, a quantity with a volume of over 15 ml is delivered, wherein the peristaltic pump is operated both in the region with the linear characteristic curve and also in the region with a non-linear characteristic curve.

8. The method for producing a medical preparation as claimed in claim 1, further comprising using an impeller to take a quantity of liquid that is to be removed from the respective source container, wherein a rotation of an impeller required to remove the quantity of liquid is calculated on the basis of the suction-side characteristic curve of the peristaltic pump.

9. The method for producing a medical preparation as claimed in claim 1, wherein at each metering step, the target container is weighed and the quantity of the respectively transferred liquid is thus checked.

10. The method for producing a medical preparation as claimed in claim 1, wherein a quantity of the liquid delivered by the peristaltic pump is calculated and the target container is weighed in order to check the quantity of the liquid delivered, wherein the sequence of different liquids in an inflow of the target container is taken into consideration in order to allow for the specific mass of the liquid in the check during weighing.

11. The method for producing a medical preparation as claimed in claim 1, wherein the target container is weighed at each individual metering step, and a quantity of the liquid transferred into the target container is thus checked at the each individual metering step.

12. The method for producing a medical preparation as claimed in claim 1, wherein a quantity of the liquid transferred into the target container in one metering step is calculated taking into account the pressure-side characteristic curve of the peristaltic pump.

13. The method for producing a medical preparation as claimed in claim 1, wherein a delivery rate of the peristaltic pump is checked with a flow sensor.

14. The method for producing a medical preparation as claimed in claim 1, wherein a metering factor of the peristaltic pump is determined in a preceding calibration step by means of weighing a target container.

15. The method for producing a medical preparation as claimed in claim 1, wherein in order to transfer the liquids from the source containers into the target container, a transfer set is used which comprises a valve unit, a hose, which is insertable into the peristaltic pump, and a plurality of hoses for attachment of the source containers.

16. An installation for producing a medical preparation, in particular an installation for producing parenteral nutrition, comprising a peristaltic pump and a system for carrying out a method as claimed in claim 1.

17. The method for producing a medical preparation as claimed in claim 1, wherein a bubble sensor is used to check that there are no bubbles in an inflow to the target container.

18. The method for producing a medical preparation as claimed in claim 1, wherein the metering factor of the pump is calibrated in a metering step from a source container in which an impeller of the peristaltic pump rotates through at least one full revolution.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The subject matter of the invention is explained below on the basis of an illustrative embodiment and with reference to FIG. 1 to FIG. 11 in the drawings.

(2) FIG. 1 shows a perspective view of an installation for producing a medical preparation, as is used for the method according to the invention.

(3) FIG. 2 is a detailed view of the peristaltic pump.

(4) Referring to FIG. 3, the characteristic curve of a peristaltic pump will be explained on the basis of an illustrative embodiment.

(5) FIGS. 4a to 4c are detailed views of the valve unit of the installation for producing a medical preparation, along with the hoses of said valve unit.

(6) FIG. 5a and FIG. 5b each show, in a flow chart, the method steps in an illustrative embodiment of the method according to the invention.

(7) FIG. 6 is a detailed view of the installation for producing a medical preparation, in which flow sensor and bubble sensor can be seen.

(8) FIG. 7 is a schematic illustration of the inflow of the target container, which illustration will be used to explain the calculation of the quantity transferred into the target container.

(9) FIG. 8 is a flow chart that will be used to explain how each metering step is checked by weighing the target container.

(10) FIG. 9 is a flow chart that will be used to explain how the weight of the liquid transferred into the target container is calculated.

(11) FIG. 10 is a flow chart that will be used to explain the monitoring via the bubble sensor.

(12) FIG. 11 is a flow chart that will be used to explain the monitoring via the flow sensor.

DETAILED DESCRIPTION OF THE DRAWINGS

(13) FIG. 1 shows an installation 1 for producing a medical preparation.

(14) The installation 1 for producing a medical preparation comprises a multiplicity of source containers 2, of which only some are shown in this view. In particular, this illustration does not show those source containers comprising the main constituents of the medical preparation, nor the container filled with universal liquid. These containers can in particular be suspended at a location remote from the installation, e.g. on a hook secured to a rail.

(15) A target container 3 can be seen which is configured as an infusion bag and is arranged on a balance 4. During the operation of the installation 1, the quantity of the liquid transferred into the target container 3 can be checked via the balance 4.

(16) To put the installation 1 into operation, a transfer set is used which comprises a valve unit 5 and hoses by means of which the valve unit 5 is connected on the one hand to the target container 3 and on the other hand to the source containers 2.

(17) During the production of a medical preparation, one valve of the valve unit 5 is opened in each metering step via the installation 1, such that liquid can be pumped from precisely one source container 2 into the target container 3.

(18) In order to deliver the liquids, the installation 1 here has a single peristaltic pump 6 by means of which liquids can be pumped from all of the source containers 2 into the target container 3.

(19) The installation 1 moreover has a display 7 which is configured as a touch screen, for example, by means of which the user can program the installation 1 and can in particular select a program by means of which a target container 3 is filled with a predefined composition of constituents.

(20) The installation comprises an electronic control (not shown) via which the peristaltic pump 6 is activated and which is connected to the balance 4.

(21) FIG. 2 is a detailed view of the peristaltic pump 6. The latter is preferably provided here as a roller pump.

(22) It will be seen that the peristaltic pump 6 has an impeller 8 with two rollers 9. The hose to be inserted is not shown in this view.

(23) It will be appreciated that the method according to the invention can also be carried out with a peristaltic pump having a different number of rollers, in particular with a peristaltic pump that comprises three rollers (not shown).

(24) When a hose (not shown) is inserted into the peristaltic pump 6, the peristaltic pump has an inlet 10 and an outlet 11. In the position of the impeller 8 shown here, both rollers 9 are in engagement with the hose.

(25) However, it will be appreciated that, when the rollers 9 move from the outlet 11 to the inlet 10, they are in part not in engagement with the hose. This results in a non-linear characteristic curve of the pump output both on the suction side, i.e. on the side of the inlet 10, and also on the pressure side, i.e. on the side of the outlet 11, and the peristaltic pump pulsates.

(26) The quantity of the liquid delivered in one full revolution is preferably between 5 and 50 ml.

(27) In order also to be able to precisely meter micro-quantities, i.e. quantities in the lower milliliter range, the peristaltic pump 6 according to one aspect of the invention is brought to a position, by rotation of the impeller 8, in which the respective micro-quantity can be metered completely in the at least suction-side linear region of the peristaltic pump 6.

(28) For this purpose, the peristaltic pump comprises a rotation angle encoder (not shown).

(29) In the position of the impeller 8 shown here, a roller 9 has just passed the inlet 10 and is now in engagement with the inserted hose.

(30) For the metering of a micro-quantity, it is recommended that the peristaltic pump 6 is brought to the position shown here in order then to be able to meter the micro-quantity completely in the region of the suction-side linear characteristic curve of the peristaltic pump 6.

(31) FIG. 3 shows the pressure-side and suction-side characteristic curve.

(32) The phase angle p is divided into 1600 units, which are plotted on the x axis. These 1600 steps represent a full revolution of the pump.

(33) The differential flow, i.e. the volume delivered per rotation angle unit, for the peristaltic pump is plotted on the y axis.

(34) The dashed characteristic curve represents the pressure-side differential flow, and the dotted characteristic curve represents the suction-side differential flow.

(35) It will be seen that the characteristic curves are constant over wide regions, i.e. regions with a linear characteristic curve are present.

(36) However, each characteristic curve has two falls. On the suction side, these are the phase angles at which one of the two rollers comes newly into engagement (p=700 and p=1500). In these regions, the volume of the hose of the peristaltic pump decreases in proximity to the suction-side attachment. The suction rate of the pump is reduced.

(37) On the pressure side, the falls are located in those regions where a roller comes out of engagement. The hose of the peristaltic pump then returns to its original shape. The hose increases its volume and the delivery rate of the pump is reduced on the pressure side.

(38) For exact metering, in particular of a micro-quantity, the delivered volume of the suction side is relevant. All the liquid removed from the source container in the respective metering step ultimately arrives at the target container. It is therefore crucial that the correct volume is removed at the suction side in each metering step.

(39) According to the invention, when metering a so-called micro-quantity, liquid is now delivered only in one of the two linear regions of the suction side of the pump in a metering step.

(40) For this purpose, before the start of the metering step, the peristaltic pump is set preferably to the start of the next linear region of the suction side by pumping of universal liquid. In this example, these positions are approximately at p=50 and p=850.

(41) Thus, micro-quantities can also be metered exactly with a single peristaltic pump.

(42) The suction-side characteristic curve of the peristaltic pump is preferably used to permit more exact calculation of the quantity of liquid removed from the source container.

(43) It is thus also possible, in metering steps that take place in the non-linear region of the peristaltic pump, to use the suction-side characteristic curve of the peristaltic pump in order to calculate the quantities of the liquid removed.

(44) It is thus taken into account, in the calculation, that the suction-side delivery rate of the peristaltic pump is not linear.

(45) Taking the characteristic curve Ds, the phase angle p2 is determined such that Vs=∫.sub.p1.sup.p2Ds(p)dp gives the volume to be metered. Here, p1 is the position of the impeller at the start of the metering step, and p2 is the position after the metering step. The variable Vs is the volume to be removed from the source container.

(46) The pressure-side characteristic curve of the pump can in turn be used to check, in an improved manner by weighing the target container, whether the quantity actually removed corresponds to the calculated quantity.

(47) For this purpose, the volume of the liquid arriving in the target container is calculated. Moreover, based on the known density of the delivered liquid, the mass of the incoming liquid is calculated. The characteristic curve Dd of the pressure side is used to determine the volume of the liquid arriving in the target container.

(48) The characteristic curves, preferably determined by empirical measurements, can be stored, for example, as approximate formulae or also as at simple value table in order to calculate the suction-side and pressure-side pump output as a function of the phase angle. In particular, the characteristic curves can be determined by measurement and then approximated by an empirical formula. The calculations in the installation then take place by means of the empirical formula or via a value table.

(49) FIG. 4a is a perspective view of the valve unit 5 used for the installation for producing a medical preparation.

(50) The valve unit 5 comprises a multiplicity of inflows 12, which are connected by hoses 15 to the source containers (2 in FIG. 1). By way of valves (not shown) integrated in the valve unit 5, a hose 15, by means of which liquid is removed from a source container, can be connected selectively to a hose 14, which is arranged at the outflow 13 of the valve unit 5.

(51) The hose 14 moreover has a portion which is placed into the peristaltic pump.

(52) FIG. 4b shows the ends of the hoses 15 for attachment of the source containers. The attachments 22 for the source containers can be seen, which attachments are configured in this illustrative embodiment as Luer lock attachments with an attached spike.

(53) FIG. 4c shows the hose 14 which forms the outflow of the valve unit 5 and at the same time the inflow of the target container. The attachment 23 for the target container can be seen.

(54) The valve unit 5 shown here forms, together with the hoses 14, 15 and the attachments 22, 23 thereof, the transfer set that is used for operating the installation.

(55) This transfer set is preferably designed as a disposable item and is regularly replaced. By virtue of this design, the liquids to be transferred come into contact only with components of the transfer set on their way from the source container to the target container.

(56) An illustrative embodiment of a method according to the invention for producing a medical preparation will be explained with reference to the flow chart in FIG. 5a and FIG. 5b.

(57) First, the above-described transfer set is used to attach the source containers. Moreover, a container known as a waste bag is inserted as target container, i.e. a container which is not intended to be used for applying a medical preparation but is instead discarded after the installation has been prepared.

(58) The whole transfer set including the hoses is filled with universal liquid (UI), for example isotonic water, and each valve is opened until the hoses (15 in FIGS. 4a and 4b) leading to the source containers are filled and free of bubbles.

(59) The metering factor of the peristaltic pump can then be determined by weighing the waste bag during the pumping of universal liquid. The pump output of the peristaltic pump, which changes particularly on account of tolerances of the used hose, is now calibrated by determination of this metering factor.

(60) The waste bag is then discarded, and the first target container that is to be filled with a medical preparation can be attached.

(61) In this illustrative embodiment, a micro-quantity is first of all intended to be metered in a first metering step.

(62) Therefore, in step 5, the impeller is brought to a region with a suction-side linear characteristic curve, with universal liquid initially being delivered during the movement of the impeller to this position.

(63) A micro-quantity can now be removed from the source container completely in the suction-side linear region of the characteristic curve of the pump.

(64) Each individual metering step, i.e. also the step for metering a micro-quantity, is checked by weighing the target container.

(65) The density of the liquid transferred into the target container is taken into consideration here by calculating which liquid or which liquids are located in the inflow of the target container and are transferred into same during the removal of the micro-quantity in step 5.

(66) Moreover, during the check made by weighing, a calculation is also made, taking into consideration the pressure-side characteristic curve of the peristaltic pump, to establish as exactly as possible which volume was transferred into the target container in the respective metering step. On account of the phase-displaced characteristic curves of suction side and pressure side, this volume does not always tally.

(67) A main constituent of the medical preparation is then metered, taking into consideration the suction-side characteristic curve of the peristaltic pump. In contrast to the metering of micro-quantities, the peristaltic pump is also operated in the non-linear region in the metering of the main constituents.

(68) However, in the calculation of the quantity of the respective main constituent removed from the source container, the suction-side characteristic curve of the peristaltic pump is taken into account in order to be able to accurately predict the volume removed on the suction side.

(69) The checking of the quantity removed from the source container for a main constituent is also carried out taking into consideration the density of the liquid transferred into the target container and taking into consideration the pressure-side characteristic curve of the peristaltic pump.

(70) In the metering of micro-quantities and also in the metering of main constituents, a further factor included in the calculation of the volume of the delivered liquid is preferably also a flow factor, which is dependent on the nature, in particular the viscosity, of the delivered liquid. Water is assigned a flow factor of 1.0; the flow factor changes considerably in the case of viscous components such as glucose solutions.

(71) It has been found sufficient to take into account a generalized flow factor as a function of the liquid removed in each metering step, since a viscosity-induced effect on the pump output is present in the first place on account of the constriction (e.g. spike) present at the attachment of the source container.

(72) The weight added to the target container in a metering step can be calculated in detail as follows:
F*Vs=∫.sub.p1.sup.p2Ds(p)dp

(73) Vs is the volume to be metered in a metering step. This volume corresponds to the volume of the suction side at which a source container is attached.

(74) p1 is the position of the impeller before the metering step, in particular the end position of a previous metering step or the start of the linear region into which the impeller was previously rotated.

(75) p2 is the calculated position of the impeller after the metering step, i.e. the result of the calculation for the rotation angle of the pump in the metering step.

(76) F is the flow factor, i.e. the correction factor for the respective viscosity of the medium.

(77) Ds(p) is the characteristic curve of the suction side (constant) and p is the phase of the impeller.

(78) The phases p1 and p2 can here differ by several revolutions.

(79) The flow factor F is therefore a correction for an additional slip of the pump by a viscosity greater than that of water. The volume to be metered is in particular higher than that of water by the factor F.

(80) Almost all media used for a medical preparation have the same viscosity as water or a higher viscosity than water. Media with a lower viscosity are very rare. Generally, therefore, F≥1.

(81) The volume which is expected on the pressure side, and on the basis of which the weight of the liquid quantity delivered to the target container in a metering step is calculated, measures:
Vd=∫.sub.p1.sup.p2Dd(p)dp

(82) This calculated weight serves for checking the respective metering step via the balance.

(83) Vd is the volume expected on the pressure side, i.e. the volume of liquid which is delivered, in the metering step, into the target container located on the balance.

(84) Dd(p) is the characteristic curve of the pressure side. The flow factor F is not included in the calculation of the volume delivered on the pressure side, since the “slip” of the pump is of course not delivered

(85) The expected mass increase G on the balance is then:
G=Vd*ρ,
with the density ρ of the delivered medium.

(86) ρ is therefore the specific weight of the liquid transferred into the target container in a metering step, i.e. initially of the liquid that is already present in the inflow of the target container. If several different liquids are transferred into the target container during a metering step, the specific weight of the liquids is correlated with their quantity.

(87) In a next step, further micro-quantities or further main constituents are delivered in further metering steps. Steps 5 to 9 can therefore be repeated until all of the desired constituents are in the target container.

(88) It will be appreciated that steps 5 to 7, i.e. the metering of a micro-quantity, and steps 8 and 9, i.e. the metering of a main constituent, are also interchangeable, i.e. can be carried out in a different sequence.

(89) At the end of each filling procedure, the transfer set is flushed with universal liquid and, if appropriate, the desired residual quantity of universal liquid is fed to the target container.

(90) It is proposed that this flushing phase for example, in which the impeller of the peristaltic pump rotates by more than one complete revolution, is utilized in order to newly determine the metering factor of the peristaltic pump during ongoing operation, by means of the target container being weighed. The metering factor can thus be recalibrated during ongoing operation. This factor may change, for example on account of the elasticity and shape of the hose inserted into the peristaltic pump changing.

(91) After all of the metering steps have been concluded and the transfer set has been flushed, the target container can be removed and a new target container attached.

(92) It will be appreciated that all of the steps shown here preferably proceed in an automated manner, except for the attachment of the source containers and target container and the start-up of the installation.

(93) FIG. 6 is a further detailed view of FIG. 1. It again shows the target container 3. A valve unit 5 can also be seen.

(94) The hose (not shown here) which connects the valve unit 5 to the target container 3, and which in particular is inserted into the peristaltic pump, is initially inserted into a flow sensor 16.

(95) The suction-side throughflow in the hose is measured via the flow sensor 16, and the delivery rate of the peristaltic pump can thus be checked for plausibility.

(96) If a blockage occurs for example in the region of the valve unit or at the attachment of a source container, the suction-side throughflow will decrease in such a way that an error can be detected by means of the flow sensor 16. Particularly when metering a micro-quantity, the hose will also contract initially in the region of the flow sensor 16, the result of which is that the detected throughflow can be reduced and a blockage can be inferred. An error message can then be generated via the electronic control and indicated to the user.

(97) The flow sensor 16 is preferably designed as an ultrasonic sensor. Particularly at low flow velocities, such a sensor is generally not accurate enough to allow the quantity of the liquid delivered on the suction side to be determined sufficiently precisely via the flow sensor alone.

(98) Therefore, the flow sensor is preferably used alone for monitoring in such a way that an error is assumed when a threshold value is exceeded as regards the difference between the calculated delivery rate of the peristaltic pump, and the resulting calculated throughflow rate, compared to the throughflow rate determined by the flow sensor.

(99) On the pressure side, the hose is inserted into a bubble sensor 17. The latter is an ultrasonic sensor which detects bubbles and, starting from a certain threshold value, switches the installation off and indicates an error to the user.

(100) FIG. 7 is a schematic view of the hose 14 which connects the valve unit 5 to the target container 3. In this illustrative embodiment, three valve units are shown arranged in succession, although this has no effect on the basic principle. The three valve units 5 shown here can equally well be combined to form a single valve unit.

(101) By means of the valve unit 5, the inflow to a source container is opened in each metering step, such that liquid from the source container can pass through the respective valve of the valve unit, initially into the valve unit and then into the hose 14.

(102) The hose 14 and the collecting channels 24 of the valve units 5 form a volume into which the liquid removed from the respective source containers is initially transferred.

(103) Therefore, the weight of the liquid arriving in the target container 3 in a metering step is not calculated on the basis of the density of the liquid removed in the respective metering step. Instead, the hose 14 and the collecting channels 24 of the valve unit(s) 5 are considered in such a way that different liquids, namely a first liquid 19, a second liquid 20 and a third liquid 21, are located in different sections of the hose 14 and/or of the attached collecting channel 24.

(104) If, for example, a micro-quantity is metered, the specific weight of the first liquid 19 is initially taken as a basis.

(105) The accuracy of the check can be improved by virtue of this theoretical “material stack”. In particular, it is possible for each individual metering step to be checked and assessed.

(106) FIG. 8 is a flow chart that will be used to explain how each metering step is checked by weighing the target container.

(107) In each metering step, the weight transferred into the target container is calculated as a desired weight. This is done, as described above, on the basis of the pressure-side characteristic curve of the peristaltic pump and the specific weight of the liquid transferred into the target container.

(108) If, during the weighing of the target container, the weight determined by the weighing deviates from the calculated weight in such a way as to breach a first limit range that would impair the quality of the medical preparation or that points to an error, the filling procedure is discontinued and an error message is output. If appropriate, the user can then rectify the error, insert a waste bag and recalibrate the installation.

(109) Otherwise, the filling procedure is continued.

(110) If the weight determined by means of the weighing does not lie within a second narrower limit range, which for example points to an insufficient calibration of the installation but points to such a slight deviation of the metered quantity that it does not impair the quality of the medical preparation, then the filling procedure is continued.

(111) However, after completion of the filling procedure, the user of the installation receives a message that the installation has to be calibrated.

(112) Otherwise, the next target container can be inserted after completion of the filling procedure.

(113) FIG. 9 is a flow chart that will be used to explain how the desired weight is calculated in a metering step.

(114) The volume of the liquid introduced is calculated on the basis of the pressure-side characteristic curve of the peristaltic pump.

(115) It is then determined which liquid or which liquids has or have arrived in the target container in the metering step. This is done in the manner described with reference to FIG. 7.

(116) The desired weight can then be calculated via the specific weight of the transferred liquid or of the liquids.

(117) This desired weight serves for the determination of the limit values mentioned in FIG. 8. Thus, for example, a first limit range could be defined as a deviation of over 10% and a second limit range could be defined as a deviation of over 5%.

(118) It will be appreciated that the limit ranges may also be varied depending on the liquid removed in a metering step, since there are constituents in which deviations in the quantity are more or less critical for the quality of the medical preparation.

(119) FIG. 10 is a flow chart that will be used to explain the monitoring via the bubble sensor.

(120) The quantity of bubbles in the transferred liquid is continuously monitored by the bubble sensor arranged downstream from the peristaltic pump.

(121) In this illustrative embodiment, two limit ranges are also provided.

(122) If the quantity of bubbles is in a limit range that is unacceptable for the quality of the product that is produced, the filling procedure is interrupted and an error message is output.

(123) If a second, narrower limit range is not complied with, the filling procedure can be continued and the target container used as intended, but an error message to the effect that the installation has to be vented is output upon completion of the filling procedure.

(124) Otherwise, the next target container can be inserted after completion of the filling procedure.

(125) FIG. 11 is a flow chart intended to explain the monitoring via the flow sensor.

(126) The flow velocity is calculated continuously, preferably on the basis of the suction-side characteristic curve of the peristaltic pump.

(127) In parallel with this, the flow velocity is measured by a flow sensor arranged at the flow side upstream from the peristaltic pump.

(128) Measured flow velocity and calculated flow velocity are compared.

(129) If a deviation is present above a threshold value, in this example 20%, an error (e.g. occlusion) is inferred and the filling procedure is discontinued.

(130) The user is informed via an error message.

(131) To be able to better locate the error, the source container from which liquid was being removed when the error occurred is preferably indicated to the user (e.g. via a number on a screen) for each error message.

(132) By virtue of the invention, the precision in the production of a medical preparation can be improved using a peristaltic pump.

LIST OF REFERENCE SIGNS

(133) 1 installation 2 source container 3 target container 4 balance 5 valve unit 6 peristaltic pump 7 display 8 impeller 9 roller 10 inlet 11 outlet 12 inflow 13 outflow 14 hose 15 hose 16 flow sensor 17 bubble sensor 18 attachment 19 first liquid 20 second liquid 21 third liquid 22 attachment 23 attachment 24 collecting channel