Closing element for a fluid line and connector thereof, and medical system utilizing the closing element and the connector

Abstract

The present invention relates to a sealing element for a fluid line, preferably for a fluid line of a concentrate container, comprising: a sealing portion configured to be disposed on an end portion of the fluid line to fluidly seal the fluid line, wherein the sealing portion includes a predetermined break point; and a pressure receiving portion configured to receive pressure applied by a connector element, the connector element being fluidly connected to the fluid line by causing the predetermined break point to break, wherein the pressure receiving portion includes at least one protrusion extending outward from at least a portion of the sealing element, the at least one protrusion being configured to contact the connector element.

Description

Closing element for fluid pipeline and connector thereof, and medical system using the same The present invention relates to a closure element for a fluid line, for example a concentrate container, for medical purposes, a connector comprising a fluid line closed by the closure element, and a system comprising a concentrate container with the connector closed by the closure element and a connector of a blood treatment device or its administration unit. During blood treatment, such as dialysis, the required dialysis solution is typically produced from a dry concentrate that is mixed with pure water. For this purpose, a container containing a concentrate, such as a bicarbonate or acid concentrate, is fluidically connected to a blood treatment device or its dosing unit to allow mixing of a solution having the desired concentrate concentration. Before the container is connected to a blood treatment device or dosing unit, the concentrate container is sealed for storage. Before fluidly connecting the container to the blood treatment device or dosing unit, seals are conventionally removed from the fluid lines of the concentrate container to open the fluid lines for connection to corresponding connector elements of the blood treatment device. Consequently, the extensive manual handling of the concentrate container conventionally presents a significant risk of contamination. Furthermore, the membrane conventionally used to seal the container can easily become dislodged during storage, resulting in the container potentially becoming contaminated and, therefore, unusable. Another common method for closing medical containers that must be fluidically connected to another fluid line for delivering the contents to a treatment machine or patient is a closure with an intended breaking edge. These closures do not need to be removed before use, but the connection is established by a portion (e.g., a spike) inserted into the closure element with the intended breaking point. This has the disadvantage that the portion establishing the connection first contacts the potentially contaminated outer surface of the closure. An object of the present invention is to alleviate or overcome the problems of the prior art. In detail, one of the objectives of the present invention is to introduce a system that can be opened from the outside while ensuring that there is no contact between the outside and the product contents. Furthermore, a safe, reliable, and hygienic means is provided for fluidically sealing a concentrate container prior to connecting it, particularly in situations where the concentrate container is not opened directly manually but rather by a blood treatment device or its dosing unit, for example by manually moving a connector element of the blood treatment device or its dosing unit. Especially when manually connecting a concentrate container to a blood treatment device or its dosing unit, it is important to ensure that only a minimum amount of force is required for the connection. This reduces the burden on personnel who must frequently perform these connections daily in everyday practice. This object is achieved by the invention as described in the independent claims. Advantageous embodiments of the invention are the subject matter of the dependent claims. A first aspect of the present invention relates to a closure element for a fluid line, preferably a fluid line of a concentrate container, comprising: a body configured to at least partially receive the fluid line, a closure portion configured to be disposed on an open portion of the fluid line to fluidically close the fluid line, wherein the closure portion comprises an intended breaking point, and a pressure receiving portion configured to receive pressure applied by a pressure applying element, preferably a connector element, which is fluidically connected to the fluid line by breaking the intended breaking point, wherein the pressure receiving portion comprises at least one protrusion, preferably extending outwardly from the closure portion or the body, the at least one protrusion being configured to contact the connector element. Preferably, the intended breaking point is an area of ​​weakened material, such as a localized thinning of the material. The intended breaking point may have the shape of a pipeline or pipelines. The closed portion may include one, two, or more than two sections, such as plate-shaped sections, separated from each other by one or more intended breaking points. Alternatively or additionally, the intended breaking point may be made of a material that is more susceptible to breaking than the material of the remainder of the closure element or a portion of the remainder. In this case, the closure element may be made of at least two components. In the most general form, the closure element may be made of two different components that differ in their mechanical properties, in particular, one component being more susceptible to breaking than the other. Preferably, both components are polymers. The targeted use of a polymer that is susceptible to breaking for selectively forming the intended breaking region of the closure element, such as the intended breaking point, offers the advantage that a substantial force is required to break the intended breaking point and thereby open the closure element. For example, the closure element may be made partly of a thermoplastic elastomer (eg, a breaking point) and another polymer (eg, linear low density polyethylene (LLDP)) forming the remainder of the closure element. During manufacturing, for example, in a first step, a portion of the closure element made of another polymer, such as linear low-density polyethylene (LLDP), is first manufactured to have a gap at the location of a portion made of a material that is more susceptible to breaking (e.g., the expected breaking point of a thermoplastic elastomer). This first step results in a portion of the closure element made of one component (e.g., linear low-density polyethylene (LLDP)) having a gap at the location of the portion to be formed from the second component (e.g., thermoplastic elastomer). In the second step, a second component, such as a thermoplastic elastomer, is added to the gaps present in the portion of the closure element made from the first component in the first step. For example, injection molding can be used to add a thermoplastic polymer (or another second component) that forms the desired breaking point to the portion of the closure element made from the first component in the first step. Additionally or alternatively, a film made from a thermoplastic polymer (or another second component) can be placed on the surface area of ​​the closure portion to seal any gaps that exist, for example, between the separate plates that form the closure portion and thereby form the desired breaking point. It is possible to place this film on a side of the closure portion that is configured to be placed on the open portion of the fluid line to fluidically close the fluid line, and / or on the side of the closure portion that faces away from the fluid line when the closure element is placed on the fluid line. The fluid line can be any pipe or hose suitable for conducting fluid. At least one protrusion of the pressure-receiving portion extends outward from the closure portion, pressure-receiving portion, or body of the closure element. In other words, the protrusion extends from at least a portion of the outer surface of the closure portion, pressure-receiving portion, or body of the closure element. For example, the protrusion can be considered a subsection of the pressure-receiving portion that protrudes outward relative to another subsection of the pressure-receiving portion. This applies even if the protrusion extends outward from the closure portion or body of the closure element. For example, because the protrusion extends outward from the closure portion, pressure can be applied to the protrusion by the pressure-applying element without the pressure-applying element having to contact the outer surface of the closure portion. This ensures that the closure portion never enters the flow path established after opening the closure element and / or remains outside the flow path. According to one embodiment of the invention, the pressure receiving portion comprises an annular projection extending along at least a portion of the outer circumference of the closure element, preferably the body thereof, or along the entire length. According to another embodiment of the invention, the closing portion comprises at least two panels separated from each other by an intended breaking point. Preferably, the closing portion comprises at least two panels which are connected to each other and / or separated from each other via an intended breaking point and are arranged at an angle to each other. In an advantageous embodiment, the two panels of the closing part, which are connected to each other by the intended breaking point and separated from each other and are arranged at an angle to each other, form a roof-like structure with a pointed front edge. According to another embodiment of the present invention, the pressure receiving portion includes a plurality of protrusions arranged along the outer circumference of the closing element, preferably at the pressure receiving portion and / or the closing portion thereof, wherein the protrusions are preferably separated from each other along the outer circumference and / or arranged at equal intervals. In principle, it is also possible to arrange a plurality of protrusions along the outer circumference of the main body. In an advantageous embodiment, the enclosed portion is formed by a plurality of plates each having the shape of a circular segment, which plates are arranged around a centre point of the enclosed portion similar to the petals of a flower. Each of the plurality of panels is preferably separated from the adjacent panels by a desired breaking point (e.g., a linear structure of localized thinning of the material). In a particularly advantageous embodiment, the closed portion comprises six panels ("petals") and more preferably, the body has a hexagonal base shape. Preferably, each of the plurality of protrusions is arranged on a plate forming the closed portion so that the pressure applied to each protrusion is selectively transmitted to the plate on which the protrusion is arranged. The pressure-applying element presses onto the plates, in particular onto the radially outward section of each plate, thereby tilting each plate like a lever, so that the radially outward section of each plate and the radially inward section of each plate move in opposite directions. The tilting movement of the plates tensions the breaking point until it breaks. The breaking of the intended breaking point can be further supported by the upper edge of the fluid line closed by the closing element, which upper edge abuts against the plate of the closed portion from the inside of the body of the closing element. In combination with the arrangement of the plates forming the closed portion and the arrangement of the intended breaking point between each two adjacent plates of the closed portion, the force required to open the closing element can be reduced. According to a further advantageous embodiment, the pressure receiving portion and / or the at least one projection thereof is present over at least half of the longitudinal length of the closure element in an insertion direction of the fluid line into the closure element. For example, if the protrusions extend outward from the body of the closure element, for example in the shape of an annular protrusion, the annular protrusion can be configured so that its length in the longitudinal direction of the closure element (for example, the direction of insertion of the fluid line into the closure element) is at least half the length of the closure element in this direction. In other words, the contact surface of the pressure receiving portion with the pressure applying element may be arranged in the distal half of the closure element in the insertion direction of the fluid line into the closure element. According to another embodiment of the invention, a groove is arranged between the closing portion and the pressure receiving portion and / or at least one protrusion thereof to allow the closing portion to move after breaking at the intended breaking point. A provision such as a groove is particularly helpful if the pressure-receiving portion and / or its at least one projection extend over at least half of the longitudinal length of the closure element in the direction of insertion of the fluid line into the closure element, and if the closure element is formed from two plates arranged at an angle to one another, thus forming a roof-like shape. After breaking at the intended breaking point, the two plates of the closure element can be moved towards a straight or vertical position without being hindered by the pressure-receiving portion and / or its at least one projection. According to another embodiment of the invention, the pressure receiving portion comprises a plurality of protrusions arranged at different positions along the longitudinal length of the closure element in the insertion direction of the fluid line into the body. For example, the closure portion may comprise at least two plates of different thicknesses, which are arranged on the body of the closure element. Due to the different thicknesses of the plates of the closure portion, the protrusions arranged on the plates are positioned at different positions along the longitudinal length of the closure element in the direction of insertion of the fluid line into the body. According to another embodiment of the present invention, at least one protrusion of the pressure receiving portion is configured in a hook shape. Additionally or alternatively, a groove is formed adjacent to at least one protrusion of the pressure receiving portion. According to an embodiment of the invention, the pressure receiving portion and / or the at least one projection thereof at least partially delimits a distal end face of the closure element in the insertion direction of the fluid line into the closure element. This has the advantage that the distance which the pressure-exerting element, which is to come into contact with the pressure-receiving portion and / or at least one projection thereof, has to travel by relative movement of pressure-exerting element and closure element before such contact is established is minimized. Alternatively, the closure element or the connector of the fluid line comprising the closure element disposed thereon can be moved relative to the pressure applying element. In this case, the distance that the closure element and / or the connector must travel to establish contact with the pressure applying element is minimized. According to an embodiment of the invention, the body has a cylindrical or polygonal, in particular a hexagonal, form. It has proven particularly advantageous if the body has a polygonal shape and the number of plates forming the closed portion corresponds to the number of edges of the polygonal body, in particular if the body has a hexagonal form and the closed portion comprises six plates. This ensures that each plate forming the closed portion can be arranged on a straight edge of the body, thereby facilitating tilting of the plates because the leverage effect is optimized. According to another embodiment of the present invention, at a connection point between the closure portion including the expected breaking point and the main body of the closure element, the material is preferably selectively weakened by providing at least one groove to promote breaking of the expected breaking point due to pressure applied to the pressure receiving portion. For example, the enclosed portion may comprise a plurality (e.g., six) plates in the shape of circular segments, arranged around a central point similar to the petals of a flower. These plates are preferably connected to a hexagonal body. At the connection points between the body and the plates, the material is preferably weakened, for example by providing an annular groove extending along the outer circumference of the body. According to another embodiment, the closure element further comprises a sealing structure at the inner circumference of the body, preferably in the form of an annular protrusion extending along the entire circumference of the body. Alternatively, the sealing function can be provided by a flush fit between the inner circumference of the body of the closure element and the outer circumference of the fluid line inserted into the body. The sealing structure may be configured to be received in a corresponding annular groove running along an outer circumference of the fluid line to removably retain the closure element to the fluid line. Furthermore, the closure element may include a groove adjacent to the sealing structure, the sealing structure being arranged radially outward from the sealing structure to allow radial movement of the sealing structure. This ensures that the closure element is easily mounted on the fluid line. According to an embodiment of the invention, the closing element is at least partially or completely made of a polymer material, in particular of linear low-density polyethylene and / or high-density polyethylene. The closure element is preferably produced by injection molding. In one embodiment of the present invention, the enclosed portion comprises six plates arranged around a central point like petals of a flower, wherein each plate has a thickness between 1 mm and 3 mm. The maximum diameter of the enclosed portion is about 16 mm and the main body has a diameter of about 10 mm. Another aspect of the present invention relates to a connector, preferably a connector for a concentrate container or other disposable article, comprising at least one fluid line providing a flow path through the connector, via which fluid can be delivered to the container to dissolve the concentrate and / or fluid can be withdrawn from the container, wherein a closure element according to the present invention is arranged on at least one fluid line of the connector to preferably fluidically close the fluid line. The at least one fluid line of the connector may comprise only one lumen (only one tube) or may comprise an inner lumen and an outer lumen (a tube within a tube). The outer lumen does not provide a flow path for conducting fluid through the connector, but is preferably configured as an annular blind hole. If the fluid line of the connector comprises only one lumen, the closure element according to the invention is preferably arranged on this lumen / tube. If the fluid line of the connector includes an inner lumen and an outer lumen, the closure element is preferably disposed on the end face of the outer lumen, and the end face of the inner lumen is configured to retract into the outer lumen so that a gap exists between the end face of the inner lumen and the closure element. This ensures that the inner lumen does not contact the closure element. The outer lumen preferably actually extends through the connector to provide a flow path therethrough. Only the inner lumen is used to conduct the fluid through the connector, and the other lumen is used to prevent the closure element from contacting the inner lumen. According to another embodiment of the present invention, the connector includes at least two fluid lines, each fluidly closed by a closure element according to the present invention, wherein the two fluid lines have different lengths, so that a pressure-applying element moving toward the connector reaches the at least two fluid lines sequentially. As a result, the at least two fluid lines are opened sequentially by the pressure-applying element. In practice, it has proven advantageous if at least one of the fluid lines of the connector comprises a sharp or pointed front edge pointing away from the connector. In particular, if the closure element comprises a closure portion which is formed by two plates arranged obliquely to one another to form a roof-shaped closure portion with an intended breaking point which connects the two plates to one another, then if the fluid line is inserted into the closure element, the sharp or pointed front edge of the fluid line of the connector corresponds to the adjacent contour of the roof-shaped closure portion. Preferably, the front edge of at least one of the fluid lines of the connector comprises two inclined sections arranged at an angle to each other. Preferably, the inclination angles of the two inclined sections are equal. According to an embodiment of the present invention, at least one of the fluid lines of the connector comprises an annular groove at its outer circumference to receive a sealing structure of a closure element, thereby securing the closure element to the fluid line. Another aspect of the present invention relates to a system comprising a closure element according to the present invention, a connector according to the present invention and a pressure-applying element, preferably a connector element of a blood treatment device or a dosing unit thereof, wherein the pressure-applying element is configured to fluidically connect the fluid line to the connector by breaking the intended breaking point of the closure element, preferably by relative movement of the pressure-applying element and the connector. The pressure applying element may be moved towards the connector comprising the closure element and / or the connector comprising the closure element may be moved towards the pressure applying element manually or automatically. According to an embodiment of the present invention, the connector, preferably a connector of a concentrate container, and / or the pressure-exerting element, preferably a connector element of a blood treatment device or a dosing unit thereof, comprises at least one fluid line comprising an inner lumen and an outer lumen, which are preferably arranged concentrically with respect to one another. Preferably, the inner lumen is configured to retract into the outer lumen. The inner lumen is used to conduct fluid, and the closure element is disposed on the outer lumen, which does not constitute a flow path through the connector but is used to ensure that the closure element does not contact the inner lumen. Alternatively, there may be only one tube and lumen, which conducts fluid and is sealed by the closure element. In other words, the present invention can be described as follows: A first aspect of the present invention relates to a closure element for a fluid line, preferably a fluid line of a concentrate container, comprising: a closure portion configured to be disposed on an end portion of the fluid line to fluidically close the fluid line, wherein the closure portion includes an intended breaking point, and a pressure receiving portion configured to receive pressure applied by a connector element that is fluidically connected to the fluid line by breaking the intended breaking point, wherein the pressure receiving portion includes at least one protrusion extending outward from the closure element, the at least one protrusion being configured to contact the connector element. The shape and number of the at least one protrusion of the pressure receiving portion may be adapted to any particular desired application. When a container containing this closure element is connected to a blood treatment device, the connector element of the blood treatment device moves in such a way that it comes into contact with the pressure-receiving portion of the closure element and applies pressure to the pressure-receiving portion. In this situation, the connector element of the blood treatment device acts as a pressure-applying element. For example, if the connector element of the blood treatment device is arranged on a movable flap of the blood treatment device, the connector element can be moved toward the connector of the container, thereby closing the fluid line by the closure element through linear or tilting movement. For example, the connector element may have an outer lumen that receives the closure element and abuts / contacts its pressure receiving portion. Alternatively, the connector carrying the closure element may be moved towards the connector element of the blood treatment device. The closure element, which preferably has the shape of a cap, is pressed down onto the fluid line until the intended breaking point of the closure portion breaks and the fluid line is fluidically opened. According to one aspect of the present invention, the pressure receiving portion comprises an annular protrusion extending along at least a portion of the outer circumference or along the entire length of the closure element, in particular its body or closure portion or pressure receiving portion. Alternatively or additionally, the pressure receiving portion may comprise a plurality of protrusions arranged along the outer circumference of the closure element, wherein the protrusions are preferably separated from each other along the outer circumference and / or arranged at equal or different intervals. The provision of a separate protrusion ensures efficient force transmission from the pressure receiving part to the intended breaking point, particularly when the closed part comprises several plates arranged around a central point like petals of a flower and the intended breaking point, for example, a line of thinner material is present between each two plates or petals. In order to reduce the amount of space required to open a fluid line covered by a closure element via a connector element of a blood treatment device, it has proven advantageous in practice for the pressure-receiving portion and / or at least one protrusion thereof to extend over at least half of the longitudinal length of the closure element in the direction of insertion of the fluid line into the closure element. In other words, the surface for establishing contact between the closure element and the pressure-applying element (or connector element) extends over the proximal half of the closure element in the direction of movement of the pressure-applying element toward the closure element. In other words, if the closure element is positioned like a cap on the side of the end of the fluid line, the protrusion of the pressure-receiving portion is not merely located at the lower end of the closure element (away from the end face of the fluid line). Instead, the protrusion extends upward at least halfway along the body of the closure element in the longitudinal direction of the closure element (the direction of insertion of the fluid line) toward the upper end of the closure element (covering the end face of the fluid line). This is particularly advantageous when the closure portion comprises two panels, which are positioned at an angle to form a roof and are connected via a central, intended breaking point. This has the advantage that if the connector element of the blood treatment device is moved downward onto the closure element to contact the pressure-receiving portion and to press the closure element downward onto the fluid line until the desired breaking point opens, the connector element of the blood treatment device must move a shorter distance before it abuts the pressure-receiving portion. Consequently, the components for fluidically coupling the concentrate container to the blood treatment device or dosing unit require less space, thereby allowing a more compact design of the dosing unit. In order to minimize the distance that a connector element of a blood treatment device must travel to establish contact with the pressure-receiving portion, the pressure-receiving portion and / or at least one protrusion thereof can be configured to define a distal end face of the closure element in the direction of insertion of the fluid line into the closure element. In other words, when the closure element is positioned on a fluid line to fluidically seal the fluid line, the plane of the upper end face of the closure element or cap can be at least partially defined by the pressure-receiving portion. In practice, it has further proven advantageous for the pressure-receiving portion to include a plurality of protrusions arranged at different positions along the longitudinal length of the closure element in the direction of insertion of the fluid line into the closure element. In this case, as the connector element of the blood treatment device is moved downward onto the closure element, the protrusions arranged at different longitudinal positions open sequentially (starting with the top protrusion) as the connector element moves from the upper end of the closure element to the lower end of the closure element. For example, if the closure portion includes several plates arranged like the petals of a flower, separated from each other by a predetermined breaking point, one or more plates may have different thicknesses, allowing the pressure-applying element to sequentially abut plates of different thicknesses. The thickness of the plates may vary depending on the specific application; for example, only one of the plates of the closure portion may have a thickness different from that of the other plates of uniform thickness. Alternatively, the thickness of two or more plates may differ from that of the remaining plates. Consequently, the flow diameter of the concentrate container opening can be gradually and sequentially increased, and the maximum force required to open the closure element can be reduced. According to an advantageous embodiment of the invention, the closure element comprises a cylindrical or hexagonal body for receiving an end portion of a fluid line. Other body geometries, such as a heptagonal, triangular or square base area, are possible and are preferred, provided that the closure element can still be arranged in the manner of a cap on the fluid line to be closed. If a hexagonal body is used in conjunction with a closure portion comprising six plates, this offers the advantage that each of the six plates of the closure portion can be positioned on a straight edge of the hexagonal body. This facilitates opening the closure element after applying pressure to the pressure-receiving portion, as the straight edges support the tilting movement of the plates of the closure portion. The plates of the closure portion act as levers to break the desired breaking point. The desired breaking point acts as a configuration-optimizing lever for the straight line disposed between the plates. The closure element, preferably in the form of a cap, may comprise a main body configured to receive a fluid line to be closed and a closure portion configured to fluidically close the fluid line. In order to facilitate breaking of the intended breaking point by the connector element and thus ensure easy and reliable opening of the container, the material can be selectively weakened, preferably by providing at least one groove, at at least one connection point between the closure part comprising the intended breaking point and the body of the closure element. In this embodiment, preferably, the closing portion and the pressure receiving portion are integrally formed so that after pressure is applied to the pressure receiving portion, the closing portion or at least a portion thereof moves by a tilting motion to break the intended breaking point. The weakening of the material at at least one connection point between the closure part and / or the pressure-receiving part and the body of the closure element, which contains the intended breaking point, allows the closure part and / or the pressure-receiving part to tilt easily and thus break the intended breaking point. This is particularly relevant if the closure part comprises a plurality of plates arranged around a central point like the petals of a flower, wherein the plates are separated from one another by a line of weakened material forming the intended breaking point. In order to improve the storage capacity of the container closed by the closure element according to the present invention, the closure element may further include a sealing structure at the inner circumference of the body, which is preferably in the form of an annular protrusion extending along the entire circumference of the body to ensure the airtight sealing of the container. Preferably, the closure element is made at least partially or completely of a polymer material, in particular of linear low-density polyethylene and / or high-density polyethylene. These materials offer the best compromise between mechanical stability, rigidity, and therefore reliable breaking, at the expected breaking point, and flexibility, thereby ensuring that the effort required to break the closure element remains reasonable. Elastomers are also possible, either alone or in combination with linear low-density polyethylene and / or high-density polyethylene. Another aspect of the present invention relates to a connector, preferably a connector for a concentrate container or other disposable product, wherein a closure element according to the present invention is fixedly or removably arranged on at least one fluid line of the connector to preferably fluidically close the fluid line. The fluid line preferably provides a flow path through the connector and can be used, for example, to conduct fluid to the concentrate container or to withdraw liquid concentrate from the container.The fluid line can be any tube or hose. The connector of the disposable may comprise at least one holding element, for example in the shape of a hook, which is configured to hold the connector near a connector element of a blood treatment device or its administration unit, to which the connector of the disposable should be connected. The disposable connector may also include structure for opening a valve in the connector element of a blood treatment machine or its dosing unit after the disposable connector is connected to the connector element of the blood treatment machine or its dosing unit. For example, the fluid line of the disposable connector may include a central rod or spike configured to dislodge the valve element from its seat in the valve of the blood treatment machine or its dosing unit, thereby enabling fluid to flow through the valve. The shape of the rod or spike is arbitrary and may be any structure suitable for opening the valve after the connector is connected to the connector element. Preferably, the fluid line of the connector comprises an internal lumen or inner tube and an external lumen or outer tube, wherein the capping element is configured on the end face of the outer lumen and the end face of the inner lumen is configured to retract into the outer lumen such that a gap exists between the end face of the inner lumen and the capping element. In other words, the outer tube is used to protect or shield the internal lumen from contact with the enclosure element. This provides the advantage of minimizing the contamination of the inner tube used to conduct the fluid. According to a favorable specific example, the connector comprises at least two fluid lines, each fluidly enclosed by a sealing element according to the present invention, wherein the two fluid lines extend from the end face of the connector to different lengths. If the concentrate container containing this connector will be connected to the blood therapy device or administration unit, the two fluid lines are sequentially opened and connected to the blood therapy device or administration unit, this is because first, the fluid line extending further from the self-connector towards the blood therapy device or administration unit is opened, and secondly, the shorter fluid line is opened and connected. Yet another state of the invention relates to a system comprising a closure element according to one of the invention, a connector according to one of the inventions (preferably a connector of a concentrate container) and at least one connector element, preferably a connector element of a blood therapy device or a administration unit thereof, wherein the connector element is configured to fluidly connect at least one fluid wired by causing the configuration of the closure element to break at that intended breaking point thereof. In this system, the following situation is confirmed to be advantageous: The connector, preferably a connector element of a blood therapy device or a administration unit thereof, contains an internal and external lumen that are better configured concentrically with each other. In each case, an internal lumen or tube and an external lumen or tube may form a fluid line. The connector element of the blood therapy machine or its administration unit may be moved and / or moved towards and / or to the connector and the fluid line of the disposable item by translational or linear movement or by rotational movement, this is because, for example, the connector element is configured in a trap plate of the blood therapy device which is tilted to make contact with the connector of the disposable item. The following situation is confirmed to be advantageous: The connector element of the blood therapy machine is configured to move with respect to the main body of the blood therapy device such that it can optionally be moved to establish a connection with the disposable item. For example, a connector element of a blood therapy device or administration unit may comprise: a portion that can be moved with respect to the body of the device, which is used to establish a fluid connection between the disposable item and the blood therapy device; Preferably, the movable portion contains the fluid line of the blood treatment device and / or is further arranged upward on the body of the blood treatment device when the blood treatment device is placed on a horizontal plane in its normal operating position. The movable portion containing the fluid line can be moved toward the connector by translation or rotation. As shown in FIG1 , a closure element 1 according to a first embodiment of the present invention is arranged in the manner of a cap at the end of a fluid line 1, preferably part of a connector for a container for concentrate. Closure element 1 comprises a closure portion 3 for fluidically sealing the fluid line, particularly its outer tube 2, a cylindrical body 4, and a pressure-receiving portion 5, which in this embodiment is configured as an annular protrusion at the lower end of closure element 1 and extends along the outer circumference of body 4. On the inner circumference of the main body 4, the closure element 1 includes an annular sealing protrusion 6 that seals the gap between the inner circumference of the main body 4 and the outer tube of the fluid line outer tube 2. The fluid line also includes an inner tube 7 that is arranged concentrically with the outer tube and terminates at an end face defined by the outer tube 2, so that the inner tube 7 is arranged to be retracted into the lumen of the outer tube 2, ensuring a gap or distance D between the end face of the inner tube 7 and the closure element 1. The fluid line has an outer lumen L1 and an inner lumen L2. The inner lumen L2 is used to conduct fluid. The inner circumference of the inner lumen L2 includes an annular sealing protrusion 8. The outer lumen L1 is not used to conduct fluid, but is used to ensure a sterile distance between the inner lumen L2 and the closure element 1. The outer lumen can be considered an annular blind hole that does not pass through the connector 12. FIG2 shows a cross section of a fluid line closed by a closure element 1 as shown in FIG1 , wherein the intended breaking point of the closure element 1 is broken by moving the connector element 9 downward onto the fluid line of the concentrate bag. In principle, it is also possible to move the connector of the concentrate bag upward toward the connector element 9, thereby breaking the closure element 1. The connector element 9 is part of a blood treatment device or a dosing unit thereof and includes an outer tube 10 configured to be pressed onto the pressure-receiving portion 5 of the closure element 1 to open the closure element 1 at a desired breaking point, as indicated by the arrow in FIG2 . The connector element 9 further includes an inner tube 11 configured to be inserted into the inner tube 7 of the connector to establish a fluid connection between the concentrate container and the blood treatment device. Through this fluid connection, fluid can be pumped into or withdrawn from the concentrate container. FIG3a shows a connector 12 for a concentrate bag according to the present invention. Connector 12 is integrally formed from a polymer material. Connector 12 includes two attachment elements 21 for attaching connector 12 to a blood treatment device. In this embodiment, attachment elements 21 have a hook shape configured to be inserted into corresponding recesses (e.g., flushing recesses) of a connector element of a blood treatment device. Typically, the connector element of a blood treatment device comprises two parts: a first part comprises at least one fluid line and is used to establish a fluid connection with, for example, a concentrate container. The second part comprises at least one recess, typically two recesses, configured to receive the at least one fluid line of the first part to short-circuit the fluid lines during flushing of the machine. In the present case, the attachment element 21 or hook of the connector 12 is configured to be inserted into these flushing recesses to secure the connector, and thus the concentrate container, to the blood treatment device. The connector 12 includes a handle 23 for moving a concentrate bag into attachment to the connector. After the connector 12 has been thus secured to the blood treatment device, the connector element of the blood treatment device, in particular the first portion thereof carrying the fluid line, is moved relative to the connector 12 to press against the closure element 1 disposed on the open end of the tube 7 of the connector 12, thereby providing a flow path through the connector and into the concentrate container. The connector element of the blood treatment device applies pressure to the closure element 1 until it breaks at its intended breaking point and opens the closure element 1. The outer tube 2 does not serve to conduct fluid, but ensures that the attachment element 21 fits securely in the flushing recess of the blood treatment device. FIG3 b shows a different embodiment of a connector 12 according to the present invention. In this embodiment, the attachment elements 21 have different shapes and are configured as curved arms extending from the body of the connector 12. These arms define a U-shaped groove 22 that is configured to receive a corresponding attachment element of a blood treatment device, which may have a strip or rod shape, for example. In FIG. 3 b , it can be seen that the connector 12 comprises two fluid lines, which are each closed by a closing element 1 . 4 shows a connector 12 of a concentrate bag according to another embodiment of the present invention, which connector comprises two fluid lines, each having only one tube 7 for conducting fluid, each fluid line being closed by a closure element 1 according to a second embodiment of the present invention. Tube 7 comprises a lumen for conducting fluid. The connector 12 shown in FIG4 includes two attachment elements 21, each of which is arranged on one of the tubes 7. Each of the attachment elements 21 includes two parallel protrusions extending outward from the outer circumference of each tube 7 in a radial direction and is arranged at different positions along the longitudinal axis of each tube 7. The attachment element 21 is configured to receive a corresponding attachment element of a blood treatment device, which may have a strip or rod shape, for example. As shown in Figure 5, the end faces of the tubes 7 of each fluid line of the connector 12 are inclined in two directions. This ensures that a greater pressure can be applied locally at the tip of the tube 7 than would be the case with a horizontal end face. It is also possible to have the end face inclined in only one direction or to have a horizontal end face. However, providing end faces that are inclined in two directions and arranged at an angle to each other has the following advantageous effect: the distance that the pressure-applying element (for example, a connector element of a blood treatment device) or the connector needs to travel can be reduced, thereby allowing a more compact design of the pressure-applying element, in particular a connector element of a blood treatment device. The geometry of the end face is variable and can be adapted to any desired application. Figure 6 shows a side view of the connector 12 of Figures 4 and 5. As shown in FIG. 7 , one or two or more or all of the fluid lines of the connector 12 may be equipped with a center rod configured to open the valve in the connector element of the blood treatment device or dosing unit by removing the valve element from the corresponding valve seat after the connector 12 is connected thereto and allowing fluid to flow through the valve. FIG8 shows a perspective view of a closure element 1 according to a second embodiment. In this embodiment, the pressure-receiving portion 5 is not only present at the lower end of the closure element 1, as shown in FIG1 , but also extends upward from the lower end face 14 of the closure element to the upper end face 15. In this embodiment, the pressure-receiving portion 5 defines the plane of the upper end face 15. This embodiment offers the advantage that the connector element 9 only needs to move a short distance before its outer tube 10 abuts the pressure-receiving portion 5 and pressure can be applied to open the closure element 1. FIG9 shows a top view of the closure element 1 of FIG8 . In this view, the intended breaking point 3a of the closure portion 3 is clearly visible. The closure portion is formed by two inclined surfaces resting against each other like a roof. The cylindrical body 4 of the closure element is visible between the closure portion 3 and the pressure-receiving portion 5 . Fig. 10 shows a cross-sectional view of the closure element of Fig. 8. The cylindrical body 4 of the closure element is visible between the closure portion 3 and the pressure receiving portion 5 and the intended breaking point 3a can easily be seen. The profile of the closing portion 3 has a roof shape and follows the profile of the front edge of the tube 7 of the connector 12 . Figure 11 shows a cross-sectional view of the closure element 1 of Figure 8 deployed on a tube 7 of a fluid line of a connector 12. The sealing structure 6 present on the inner circumference of the body 4 of the closure element 1 is received in a corresponding annular groove in the outer circumference of the tube 7 to removably lock the closure element 1 to the tube 7 via a form-fit mechanism. A groove 24 exists between the closing portion 3 and the pressure receiving portion 5. This groove 24 allows the two angled plates of the closing portion 3 to move towards a straight position after breaking at the intended breaking point 3a. Another groove 25 is present in a position radially outward from the sealing structure 6 to allow the sealing structure 6 to be flexibly moved after a fluid line, such as a tube 7 , has been inserted into the closure element 1 . Figure 12 shows the first step in the connection process of the connector 12 and closure element 1 of Figure 11 to the connector element 9 of the blood treatment device. In this step, the connector element 9 and the tube 7 are aligned and brought into proximity with each other. The connector 12 is attached to the connector element of the blood treatment device via the attachment element 21 including the protrusion 21a. Figure 13 shows the second step in the connection process of the connector 12 and closure element 1 of Figure 11 to the connector element 9 of the blood treatment device. At this stage, the connector element 9 has been moved downward toward the connector 12 until the outer tube 10 of the connector element 9 presses onto the pressure receiving portion 5 of the closure element 1, and the closure element 1 is moved downward in the longitudinal direction of the tube 7 until the closure element is opened as shown in Figure 13. As shown in FIG14 , in a third step, the connector element 9 is moved further downward until the center stem 13 of the tube 7 enters the interior lumen of the inner tube 11 of the connector and thereby removes the valve element 16 from its valve seat to enable fluid to flow through the lumen of the inner tube 11 into the concentrate container. FIG15 shows a perspective view of a closure element 1 according to a third embodiment. The closure element comprises a body 4 and, in this embodiment, six elements or plates movably attached to the body 4, which together form the closure element's closure portion 3 and pressure-receiving portion 5. These elements are arranged in the manner of petals. Each plate has a circular cross-section. The outer edges of each plate in the radial direction are rectangular. At its outer edge, each of these petals is equipped with a protrusion 5a, which is part of the pressure-receiving portion 5 and can be configured as a hook to hold, for example, an external tube 10 of a connector element 9 of a blood treatment device. Each plate or petal, and in particular its pressure-receiving portion, projects outwardly above the body 4 of the closure element 1, making it easy to tilt each plate after pressure is applied to it or on the petals. The plates thus act as levers. The elements forming the petals of the flower shape are separated from each other by the intended breaking points 3a. Providing separate protrusions in combination with the design of the intended breaking points and the shape of the plate has the advantageous effect that the forces and strains acting on the intended breaking points after pressure is applied to the plate are optimized. FIG. 16 shows a cross-sectional view of the closure element of FIG. 15 . Figure 17 shows a first step in the connection process of the tube 7 closed by the closure element 1 of Figure 15 to the connector element 9 of the blood treatment device. In the stage shown in Figure 17, the connector element 9 and the tube 7 including the closure element 1 are aligned with each other. In the stage shown in FIG. 18 , the connector element 9 has been moved towards the closure element 1 , so that the leading edge of the outer tube 10 abuts the pressure receiving portion 5 of the closure element 1 . 19 , the connector element 9 has been moved further onto the tube 7 and is pressed onto the pressure-receiving portion 5 of the closure element 1, so that the closure portion 3 of the closure element and therefore its intended breaking point 3a are tensioned due to the tilting or rotational movement of the elements (“petals”) forming the closure portion 3. The edge of the tube 7 is pressed against the elements forming the closure portion from the inside of the closure element 1 to facilitate opening the closure element. At the stage shown in Figure 20, the connector element 9 has moved so far onto the tube 7 that the pressure exerted on the pressure-receiving portion 5 of the closure element 1 exceeds the force required to break the intended breaking point 3a, which breaks in Figure 20. As shown in Figure 20, the elements ("petals") forming the closure portion 3 tilt or rotate, thereby opening the closure element 1. Thus, in this embodiment, the closure element 1 is opened by a tilting or rotational movement of an element of the closure part which acts as a lever. 21 shows a cross-sectional view of a closure element 1 according to another embodiment. In this embodiment, the material at the connection points 17 between the elements ("petals") forming the closure portion 3 and the pressure-receiving portion 5 and the body 4 of the closure element 1 has been selectively weakened to ensure that the elements ("petals") forming the closure portion 3 and the pressure-receiving portion 5 can easily tilt / rotate after pressure is applied. The weakening of the material preferably involves the removal of up to 50% of the material, preferably up to 30% or up to 20% of the material. Depending on the material, the removal of up to 80% of the material is possible. FIG22 illustrates the sequential opening of two fluid lines (in this case, their inner tubes 7), each of which is closed by a closure element 1 according to the present invention. The inner tube 7, positioned on the left side in FIG22 , extends further from the connector 12 and is therefore closer to the connector element 9 of the blood treatment device. As the connector element 9 of the blood treatment device moves toward the connector 12, it reaches the tube 2 on the left first, and this tube is therefore opened first. Figure 23 shows a cross-sectional view of a closure element 1 according to yet another embodiment. In this embodiment, the body 4 of the closure element 1 has a hexagonal shape. The closure portion 3 and the pressure receiving portion 5 are formed by six elements arranged like the petals of a flower. In this embodiment, each protrusion 5a of the pressure receiving portion 5 of each petal is formed by a groove or recess 5b. The protrusion 5a projects relative to the surface defined by the groove 5b. As illustrated in FIG. 23 , the protrusion 5 a of the pressure receiving portion 5 and / or the elements forming the closing portion 3 and / or the pressure receiving portion 5 may be arranged at different positions along the longitudinal direction of the closing element 1 . For example, in FIG23 , the element positioned at the top in the longitudinal direction is designated by reference numeral 18. The element positioned at the second top in the longitudinal direction of the four elements is designated by reference numeral 19. The element designated by reference numeral 20 is positioned lowest in the longitudinal direction of the closure element 1. Thus, the topmost element 18 has a greater thickness than the middle elements 19, and the lowest element 20 has the smallest thickness. The topmost element 18, the middle elements 19, and the lowest element 20 forming the closure portion 3 are attached to the hexagonal body 4 at the same longitudinal position—for example, at a common continuous edge of the hexagonal body. In this embodiment, these elements are plates. Therefore, if the connector element 9 of the blood treatment device is moved from the top in FIG23 onto the closure element 1, the leading edge of the outer tube 10 of the connector element 9 first strikes the topmost element 18, then the middle element 19, and finally the lowest element 20. As a result, the flow cross section of the closure element is sequentially and gradually enlarged. Furthermore, the force required to open the closure element is reduced. 24a shows a machine connector 30 of a blood treatment device 26, comprising a first part 27, which is rotatably movable about a hinge 28, and a second part 29. In the state shown in FIG24a , the connector element 26 is closed so that the first part 27 abuts the second part 29, which is immovably fixed to the blood treatment device 26. The first portion 27 includes two connector elements 9 in the form of fluid lines, which are used to fluidically connect the blood treatment device 26 to, for example, a concentrate container. The connector elements 9 can have the configurations shown in Figures 1, 2, and 17 to 20. The first portion 27 can have the form of a lid or flap that can be moved via a hinge 28. Movement of the first portion 27 can be achieved manually or automatically via a motor. Movement of the first portion 27 opens the closure element 1 on the connector 12 and establishes a fluid connection between the blood treatment device 26 and the connector 12. FIG24 b shows the machine connector 30 of FIG24 a in the open position. The connector 12 has been secured to the second part 29. The second part 29 includes two recesses (not visible in FIG24 b ) into which the two attachment elements 21 of the connector 12 have been inserted. The first part 27 includes two connector elements 9 , or fluid lines, which can each be inserted into a recess in the second part 29 for flushing or can be used to establish a fluid connection with a concentrate container via the connector 12. The connector element 9 / fluid line of the first portion of the machine connector 30 of the blood treatment device 26 preferably each comprises an inner tube 11 and an outer tube 10, thus containing two lumens. The inner tube 11 is used to conduct fluid and is configured to retract within the outer tube 10. The outer tube 10 is used, for example, to apply pressure to the closure element 1. After the closure element 1 has been opened by the outer tube 10, the inner tube 11 is inserted into the fluid line of the connector 12 (e.g., tube 7) to fluidically connect the blood treatment device 26 and the connector 12 to the concentrate container attached thereto. Therefore, the sterile inner tube 11 never comes into contact with the non-sterile closure element 1. A valve including a valve element 16 can be disposed in the lumen of inner tube 11. The fluid line of connector 12, such as tube 7, includes a member 13, such as a central rod, for opening the valve by displacing valve element 16. Thus, the valve is opened only after connector 12 is connected to the machine connector 30 of the blood treatment device. This prevents fluid from escaping from connector element 9 or the fluid line. To connect the blood treatment device to the concentrate container, the first part 27 of the machine connector 30 is moved downwards towards the connector 12 until the fluid line / connector element 9 is inserted into the connector and opens the closure element present on the fluid line / tube of the connector 12 . The connector 12 is secured to the second portion 29. The second portion 29 includes attachment means to which the connector 12 can be secured via its attachment element 21. The attachment means of the second portion 29 can be, for example, grooves (such as groove 31) or protrusions (such as protrusion 32). These attachment means are preferably fixedly and immovably connected to the blood treatment device 26. Between treatment sessions, the connector element 9 of the blood treatment device 26 needs to be flushed or sterilized. For this purpose, the connector element 9 of the first part 27 is inserted into the recess 31 of the second part 29 until the lumen of the outer tube 10 is fluidically sealed. The inner tube 11 is configured to retract into the lumen of the outer tube 10 and can therefore be flushed in this position because the connector element 9 is fluidically short-circuited. In this case, the irrigation fluid is supplied through the lumen of the inner tube 11 and removed to a drain through the lumen of the outer tube 10. Each irrigation recess 31 can be equipped with a structure for actuating a valve to allow the flow of irrigation fluid. These valve actuators can have the shape of a central rod 34 (see Figure 26). In addition, the irrigation recess 31 can also be equipped with a drain to remove excess irrigation fluid. FIG25 shows a different machine connector 30 of a blood treatment device 26, whose first part 27 is movable in translation. FIG25 shows a flushing groove 31 in the second part 29 of the machine connector 30. The connector 12 can be fixed to the second part 29 by inserting the attachment element 21 into the flushing groove 31, and the first part 27 including the connector element 9 is then moved downward to establish a fluid connection between the blood treatment device and the concentrate container via the connector 12. FIG26 shows the connector 12 of the concentrate container, which is attached to a blood treatment device 26 via its attachment element 21. The second part 29 of the machine connector of the blood treatment device 26 comprises a movable drawer 33, which includes a flushing recess 31. It is also possible to arrange the flushing recess 31 in a fixed position relative to the blood treatment device 26. The movable drawer 33 further comprises a rod-shaped attachment element 32. The connector 12 comprises an attachment element 21 in the shape of a bent arm, which is configured to receive a corresponding attachment element 32 of the blood treatment device in the shape of a rod. In the embodiment shown in FIG26 , the connector is therefore not fixed to the blood treatment device via the flushing groove 31 but via separate attachment elements 32 and 21 that interact with each other. After connecting the connector 12 to the movable drawer 33 of the second part 29 , the movable drawer 33 is then moved toward the blood treatment device 26 . 1: Closure element 2: Outer tube 3: Closure portion 3a: Expected breaking point 4: Main body 5: Pressure receiving portion 5a: Protrusion 5b: Groove or recess 6: Annular sealing protrusion / sealing structure 7: Inner tube 8: Annular sealing protrusion 9: Connector element 10: Outer tube 11: Inner tube 12: Connector 13: Member / Center rod 14: Lower end surface 15: Upper end surface 16: Valve element 17: Connection point 18: Topmost element 19: Intermediate element 20: Lowermost element 21: Attachment element 21a: Protrusion 22: U-shaped groove 23: Handle 24: Groove 25: Groove 26: Blood treatment device 27: First part 28: Hinge 29: Second part 30: Machine connector 31: Groove 32: Protrusion / Attachment element 33: Removable drawer 34: Center rod D: Gap or distance L 1: External lumen L 2: Internal lumen Other features, effects and advantages of the present invention will become apparent from the detailed description of the embodiments of the present invention with reference to the accompanying drawings. The same or similar components are indicated by the same reference symbols.In the drawings: [FIG. 1] shows a cross section of a fluid line closed by a closure element according to a first embodiment of the present invention; [FIG. 2] shows a cross section of a fluid line closed by a closure element according to the first embodiment of the present invention as shown in FIG. 1 , wherein the intended breaking point of the closure element is broken; [FIG. 3a] shows a connector of a concentrate bag according to the present invention; [FIG. 3b] shows another connector of a concentrate bag according to the present invention; [FIG. 4] shows a connector of a concentrate bag according to the present invention, comprising two fluid lines each closed by a closure element according to a second embodiment of the present invention; [FIG. 5] shows a perspective view of the connector of FIG. 4; [FIG. 6] shows a side view of the connector of FIG. 4; [FIG. 7] shows a cross-sectional view of the connector of FIG. 4; [FIG. 8] shows a perspective view of a closure element according to the second embodiment; [FIG. 9] shows a top view of the closure element of FIG. 8; [FIG. 10] shows a cross-sectional view of the closure element of FIG. 8; [FIG. 11] shows a cross-sectional view of the closure element of FIG. 8 arranged on a fluid line of the connector of FIG. 4; [Figure 12] shows a first step in a process of connecting the connector and closure element of Figure 11 to the connector element of a blood treatment device; [Figure 13] shows a second step in a process of connecting the connector and closure element of Figure 11 to the connector element of a blood treatment device; [Figure 14] shows a third step in a process of connecting the connector and closure element of Figure 11 to the connector element of a blood treatment device; [Figure 15] shows a perspective view of a closure element according to a third embodiment; [Figure 16] shows a cross-sectional view of the closure element of Figure 15; [Figure 17] shows a first step in a process of connecting the connector and closure element of Figure 15 to the connector element of a blood treatment device; [Figure 18] shows a second step in a process of connecting the connector and closure element of Figure 15 to the connector element of a blood treatment device; [Figure 19] shows a third step in a process of connecting the connector and closure element of Figure 15 to the connector element of a blood treatment device; [Figure 20] shows a fourth step in a process of connecting the connector and closure element of Figure 15 to the connector element of a blood treatment device; [Figure 21] shows a cross-sectional view of a closure element according to another embodiment; [Figure 22] illustrates the sequential opening of two fluid lines, each of which is closed by a closing element according to the present invention; [Figure 23] shows a cross-sectional view of a closing element according to another embodiment; [Figure 24a] shows a machine connector of a blood treatment machine that can be moved by rotation in a closed state; [Figure 24b] shows the machine connector of Figure 24a in an open state; [Figure 25] shows different machine connectors of a blood treatment machine that can be moved translationally; [Figure 26] shows a connector of a concentrate container attached to a blood treatment device. 1: Closing element 2: External tube 4: Subject 5: Pressure receiving part 6: Annular sealing protrusion / sealing structure 7: Inner tube 8: Annular sealing protrusion D: Gap or distance L1: external lumen L2: internal lumen

Claims

1. A sealing element for a fluid line, preferably for a fluid line of a concentrate container, comprising: a body configured to at least partially receive the fluid line; a sealing portion configured to be disposed on an open portion of the fluid line to fluidly seal the fluid line, wherein the sealing portion includes a predetermined break point; and a pressure receiving portion configured to receive pressure applied by a pressure applying element, preferably a connector element, to fluidly connect to the fluid line by causing the predetermined break point to rupture; wherein the pressure receiving portion includes at least one protrusion, preferably extending outward from the sealing portion or the body, the at least one protrusion configured to contact the connector element; wherein the pressure receiving portion includes an annular protrusion extending at least along a portion of the outer circumference of the sealing element, preferably its body, or along its entire length; wherein... The at least one protrusion is configured such that when pressure is applied to the protrusion, a force can be applied to the intended fracture point of the closed portion.

2. The closing element as claimed in claim 1, wherein the closing portion comprises at least two plates separated from each other by the intended break point.

3. The closing element as claimed in claim 1 or 2, wherein the closing portion comprises at least two plates separated from each other by the expected break point and arranged at an angle to each other.

4. The closing element as claimed in claim 1 or 2, wherein the pressure receiving portion includes a plurality of protrusions disposed along the outer circumference of the closing element, preferably disposed at the pressure receiving portion, wherein the protrusions are preferably separated from each other and / or disposed at equal intervals along the outer circumference.

5. The closure element of claim 4, wherein each of the plurality of protrusions is disposed on a plate forming the closure portion such that pressure applied to each protrusion is selectively transmitted to the plate on which the protrusion is disposed.

6. The closure element of claim 5, wherein the pressure receiving portion and / or at least one of its protrusions are present on at least half the longitudinal length of the closure element in one of the insertion directions of the fluid line to the closure element.

7. The closure element of claim 6, wherein the pressure receiving portion and / or at least one of its protrusions at least partially defines one distal face of the closure element in the insertion direction from the fluid line to the closure element.

8. The closing element of claim 5, wherein the body has a cylindrical or polygonal form, especially a hexagonal form.

9. The closure element of claim 5, wherein at a connection point between the closure portion containing the expected fracture point and the body of the closure element, the material is selectively weakened, preferably by providing at least one groove, to facilitate fracture of the expected fracture point due to pressure applied to the pressure receiving portion.

10. The closure element of claim 1 or 2, wherein the closure element is made at least partially or entirely of a polymeric material, particularly linear low-density polyethylene and / or high-density polyethylene.

11. The closing element of claim 10, wherein the closing element is formed of at least two polymers, one of which is preferably more brittle than the other, and the more brittle polymer preferably forms the intended fracture point.

12. A connector, preferably a connector for a concentrate container or other disposable product, comprising at least one fluid line providing a flow path through the connector, wherein a closure element as claimed in any one of claims 1 to 11 is disposed on at least one fluid line of the connector to preferably fluidly close the fluid line.

13. The connector of claim 12, wherein the fluid line comprises a single lumen or comprises an inner lumen and an outer lumen, wherein the closure element is disposed on one end face of the single lumen or the outer lumen, and one end face of the inner lumen is configured to retract into the outer lumen such that a gap exists between the end face of the inner lumen and the closure element.

14. A connector as claimed in any of claims 12 to 13, wherein at least one of the fluid lines of the connector includes a sharp or pointed front edge away from the connector.

15. A medical system comprising: a closure element as claimed in any one of claims 1 to 11; a connector as claimed in any one of claims 12 to 14; and a pressure application element, preferably a connector element of a blood therapy device or a drug delivery unit thereof, wherein the pressure application element is configured to be fluidly connected to the fluid line of the connector by causing the closure element to break at the intended break point, preferably by relative movement of the pressure application element and the connector.

16. The medical system of claim 15, wherein the connector, preferably a connector for a concentrate container and / or the pressure application element, preferably a connector element for a blood therapy device or a drug delivery unit thereof, includes at least one fluid line, the at least one fluid line including an inner lumen and an outer lumen preferably concentrically arranged with respect to each other.

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