A hydrophobic self-cleaning PPR pipe

Abstract

This utility model discloses a hydrophobic self-cleaning PPR pipe, relating to the field of pipe technology. It includes a hydrophobic guiding layer and a flow guiding layer connected sequentially from the inside out. A porous water-absorbing buffer layer is provided between the hydrophobic guiding layer and the flow guiding layer. Several flow guiding grooves are provided along the pipe axis on the surface of the flow guiding layer. The surface of the hydrophobic guiding layer is coated with a nano-layer, and several lotus leaf-shaped nipple structures are formed on the surface of the nano-layer. Spherical water droplets form point contact with the lotus leaf-shaped nipple structures, which can conveniently and quickly handle condensate generated inside the pipe, ensuring normal pipe operation, extending service life, and ensuring the safety and stability of media transportation.

Description

Technical Field

[0001] This utility model relates to the field of pipe technology, and more specifically, to a hydrophobic self-cleaning PPR pipe. Background Technology

[0002] In actual operating conditions, PPR pipes often encounter condensation problems due to factors such as temperature changes and humidity differences. For example, in hot water supply systems, when hot water stops flowing through the pipes, although there is no water inside, the residual heat inside the pipes causes water vapor in the surrounding air to condense upon contact with the cold air, forming condensate. Similarly, in environments with frequent temperature fluctuations, the surface temperature of PPR pipes constantly changes, easily leading to condensation buildup. Long-term water accumulation not only corrodes the inner walls of the pipes, reducing their strength and increasing the risk of leaks, but it can also breed bacteria, algae, and other microorganisms, contaminating the medium flowing through the pipes and threatening water quality safety.

[0003] Chinese Patent Publication No. CN219221512U, Publication Date: June 20, 2023, discloses a Chinese patent entitled "A PPR Water Supply Pipe," which includes a pipe body. The pipe body comprises, from the inside out, a hydrophobic layer, a PPR inner pipe layer, a toughening and insulation layer, a PPR outer pipe layer, a reinforcing layer, and an outer anti-corrosion layer. The toughening and insulation layer includes several high-elasticity toughening rubbers arranged longitudinally along the pipe body, with insulation filler filling the gaps between the high-elasticity toughening rubbers. Although this pipe has an internal hydrophobic layer, it cannot promptly drain condensate from the pipe, posing a threat to water quality safety. Utility Model Content

[0004] This invention provides a hydrophobic self-cleaning PPR pipe. By setting a hydrophobic guiding layer, a porous water-absorbing buffer layer, and a flow guiding layer, it can conveniently and quickly handle the condensate generated in the pipe, ensure the normal operation of the pipe, extend its service life, and ensure the safety and stability of media transportation.

[0005] A further objective of this invention is to reduce the humidity inside the pipe, thereby achieving a drying effect.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a hydrophobic self-cleaning PPR pipe, comprising a hydrophobic guiding layer and a flow guiding layer connected sequentially from the inside to the outside, a porous water-absorbing buffer layer provided between the hydrophobic guiding layer and the flow guiding layer, and a plurality of flow guiding grooves penetrating along the pipe axis on the surface of the flow guiding layer; the surface of the hydrophobic guiding layer is coated with a nano layer, and a plurality of lotus leaf papillae structures are formed on the surface of the nano layer, and point contact is formed between the spherical water droplets and the lotus leaf papillae structures.

[0007] Preferably, condensate forms spherical droplets in the nanolayer, with the angle between these droplets and the tips of the lotus leaf-like papillae structures exceeding 150 degrees. This creates a strong rolling tendency, achieving the hydrophobicity of the PPR pipe's inner wall and ensuring efficient self-cleaning capabilities. Even with a small pipe inclination angle, the droplets quickly roll to lower areas, preventing stagnation and water film formation, thus reducing condensate buildup at its source. The dense inner nanostructure, with numerous tiny lotus leaf-like papillae structures on its surface, traps air in the gaps when water contacts the inner wall. The internal water flow makes point contact with the tips of the protruding structures, resulting in weak surface adhesion. Under surface tension, the water agglomerates into spheres and rolls freely on the inner surface. Simultaneously, bacteria within the pipe exhibit minimal adhesion to the inner wall and are easily carried away by the water, achieving both hydrophobicity and self-cleaning properties. This reduces condensate retention time, lowering the probability of chemical corrosion of PPR pipes by chloride ions and oxygen in the water. This is particularly suitable for pipeline systems in humid and hot environments or those transporting high-temperature media, extending the pipe's service life.

[0008] Preferably, the thickness of the nanolayer is between 0.05 and 0.2 mm. The nanolayer is coated with a specially surface-treated nanomaterial, preferably a nano-titanium dioxide coating. This layer has extremely low surface energy, causing condensate to form spherical water droplets on its surface. This thickness range ensures that the nanolayer has sufficient papillary structure density (tens of thousands to hundreds of thousands of papillae per square millimeter) to form a stable superhydrophobic surface, while avoiding excessive coating thickness that would reduce adhesion to the PPR substrate, ensuring that it does not peel or fail during long-term use. The coating thickness of 0.05-0.2 mm can be precisely controlled using existing coating equipment (such as electrostatic spraying and dip coating), without requiring modification of the PPR pipe production line, reducing technology upgrade costs, and making it suitable for large-scale industrial applications.

[0009] Preferably, the porous absorbent buffer layer is made of polymer fiber material with a thickness between 0.5-2 mm. The polymer fiber material is hydrophilic, such as polyvinyl alcohol fiber nonwoven fabric. The hydrophilic fiber material can quickly absorb and store excess water droplets, preventing a large amount of condensate from rushing into the drainage layer in a short time and causing poor drainage. It is especially suitable for scenarios where condensate is not generated continuously, such as air conditioner condensate pipes and steam pipes.

[0010] Preferably, the fibers within the porous absorbent buffer layer form interconnected pores. On one hand, this allows for the rapid absorption of water droplets rolling from the superhydrophobic guiding layer, buffering the rate of condensation buildup. On the other hand, its hydrophilic properties ensure that even with a high condensation rate, water can be temporarily retained, preventing excessive accumulation at the bottom of the pipe. The interconnected pores form a three-dimensional water-conducting channel, allowing water droplets rolling into the porous absorbent buffer layer to quickly diffuse and permeate, preventing saturation and failure of the buffer layer due to localized water accumulation. The interwoven structure between the fibers improves the tensile strength of the buffer layer, ensuring it is less prone to breakage or deformation even during thermal expansion and contraction of the pipe, guaranteeing long-term functional reliability.

[0011] Preferably, the pore diameter is between 1 and 10 μm. This pore size range generates significant capillary suction, acting like a "miniature straw" to actively attract spherical water droplets from the hydrophobic guiding layer, accelerating the transfer of water droplets from the nanolayer to the buffer layer. Even when the pipe is installed horizontally, it ensures that condensate can be removed from the hydrophobic surface in a timely manner. The pore size ensures efficient water conduction while preventing excessively large pores from causing water to directly pass through the porous absorbent buffer layer and impact the guiding layer, thus balancing the water absorption rate and resistance control.

[0012] Preferably, the flow guide layer is composed of a high-molecular polymer composite. The high-molecular polymer can be simultaneously formed with the PPR pipe through processes such as extrusion and injection molding, eliminating the need for secondary processing, reducing production costs, and ensuring the bonding strength between the flow guide layer and the pipe body to prevent delamination.

[0013] Preferably, the thickness of the flow guide layer is between 0.1 and 0.5 mm. The low thermal conductivity of the polymer can reduce heat transfer from the flow guide layer to the outer wall of the pipe, thereby reducing the surface temperature of the pipe and minimizing heat loss and the risk of scalding when transporting hot water or steam.

[0014] Preferably, the flow-guiding groove has a Y-shaped cross-section, and the drain plug is installed on the starting end face of the pipe. The design of the flow-guiding groove allows water seeping from the porous absorbent buffer layer to flow quickly to the water collection area at the bottom of the pipe, accelerating the drainage process. Simultaneously, its nanomaterial components enhance the wear resistance and corrosion resistance of this layer, ensuring the stable performance of the hydrophobic layer structure during long-term use. The drain plug allows for periodic removal and drainage, ensuring the service life of the PPR pipe and solving the problems of condensate accumulation and poor drainage encountered by PPR pipes during use.

[0015] Preferably, when the internal water flow comes into contact with the lotus leaf papillae structure, it can agglomerate into a spherical shape under the action of surface tension.

[0016] The beneficial effects of this utility model are as follows: 1) A hydrophobic guiding layer is set on the inner wall of the pressure-bearing layer, and the hydrophobic protrusions can reduce the water flow resistance of the pipe, reduce the head loss of the entire system, indirectly improve the energy utilization rate, effectively solve the problem of condensate accumulation in PPR pipes, and significantly improve the reliability, durability and safety of the transported medium of PPR pipes.

[0017] 2) The hydrophobic guiding layer can allow water flow to wash away a certain number of bacteria adhering to the inner wall of the pipe, reduce secondary pollution of water, achieve a certain self-cleaning ability, reduce the humidity inside the pipe, and play a drying role.

[0018] 3) This pipeline minimizes water flow resistance within the pipeline, allowing water to be delivered more smoothly to the end user and improving user comfort.

[0019] 4) The mature production process of PPR pipes changes the inner wall molding structure of the pipe at the micro level without affecting production stability, thus maintaining high-efficiency production. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of this utility model.

[0021] Figure 2 for Figure 1 Enlarged view of point A.

[0022] Reference numerals: 1: Hydrophobic guiding layer; 2: Porous water-absorbing buffer layer; 3: Flow guiding layer; 4: Flow guiding groove; 5: Lotus leaf papilla structure; 6: Spherical water droplet. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] PPR pipes are widely used in many fields such as building water supply and drainage, and heating due to their excellent chemical stability and good hot-melt welding performance. However, in actual working conditions, PPR pipes often encounter the problem of condensation formation caused by factors such as temperature changes and humidity differences. For example, in hot water supply systems, when hot water stops flowing through the pipe, the residual heat inside the pipe causes water vapor in the surrounding air to condense upon contact with the cold air, forming condensate. Similarly, in environments with frequent temperature fluctuations, the surface temperature of PPR pipes changes constantly, which also easily leads to condensation accumulation.

[0025] Traditional methods, such as attaching steam traps to the outside of the piping system or periodically manually cleaning accumulated water, have many drawbacks. Steam traps are complex to connect to PPR pipes, have high installation and maintenance costs, and are prone to loosening or damage at the connection points due to the thermal expansion and contraction of PPR pipes. Manual cleaning of accumulated water is inefficient, making it difficult to detect and address problems promptly. Long-term water accumulation not only corrodes the inner wall of the pipe, reducing its strength and increasing the risk of leaks, but can also breed bacteria, algae, and other microorganisms, contaminating the medium flowing through the pipe and threatening water quality. Therefore, there is an urgent need for a highly efficient, self-adaptive hydrophobic layer structure built into PPR pipes to overcome these problems.

[0026] This invention provides a hydrophobic self-cleaning PPR pipe. By setting a hydrophobic guiding layer 1, a porous water-absorbing buffer layer 2, and a flow guiding layer 3, it can accurately, conveniently, and quickly handle the condensate generated in the pipe, ensuring the normal operation of the pipe, extending its service life, and ensuring the safety and stability of media transportation.

[0027] like Figure 1 and Figure 2 As shown, a hydrophobic self-cleaning PPR pipe includes a hydrophobic guiding layer 1 and a flow guiding layer 3 connected sequentially from the inside to the outside. A porous water-absorbing buffer layer 2 is provided between the hydrophobic guiding layer 1 and the flow guiding layer 3. The whole structure is a three-layer structure. Several flow guiding grooves 4 are provided through the surface of the flow guiding layer 3 along the pipe axis. The surface of the hydrophobic guiding layer 1 is coated with a nano layer. Several lotus leaf nipple structures 5 are formed on the surface of the nano layer. The spherical water column and the lotus leaf nipple structures 5 form point contact.

[0028] In a preferred embodiment, condensate forms spherical water droplets 6 in the nanolayer. The angle between the spherical water droplets 6 and the tip of the lotus leaf-like papilla structure 5 is greater than 150 degrees, thus possessing a strong rolling tendency. This achieves the hydrophobicity of the PPR pipe's inner wall, ensuring the pipe's efficient self-cleaning ability. Even with a small pipe inclination angle, the water droplets can quickly roll to the lowest point, avoiding stagnation and the formation of a water film, thereby reducing condensate accumulation at the source. The inner nanostructure is dense, with numerous tiny lotus leaf-like papilla structures 5 on the surface. When water comes into contact with the inner wall, the air in the protruding gaps is locked, and the internal water flow forms point contact with the tips of the protruding structures. The surface adhesion is very weak, and under the action of surface tension, it can agglomerate into a spherical shape and roll freely on the inner surface. At the same time, the internal bacteria have very little adhesion to the inner wall surface and are easily carried away by the water, thus achieving hydrophobicity and self-cleaning effects inside the pipe. Reducing the residence time of condensate can lower the probability of chemical corrosion of PPR pipes by chloride ions and oxygen in water, making it especially suitable for pipeline systems in humid and hot environments or transporting high-temperature media, thus extending the service life of the pipes.

[0029] In a preferred embodiment, the thickness of the nanolayer is between 0.05 and 0.2 mm. The nanolayer is coated with a specially surface-treated nanomaterial, preferably a nano-titanium dioxide coating. This layer has extremely low surface energy, causing condensate to form spherical water droplets on its surface. This thickness range ensures that the nanolayer has sufficient papillary structure density (tens of thousands to hundreds of thousands of papillae per square millimeter) to form a stable superhydrophobic surface, while avoiding excessive coating thickness that would reduce adhesion to the PPR substrate, ensuring no peeling or failure during long-term use. The coating thickness of 0.05-0.2 mm can be precisely controlled using existing coating equipment (such as electrostatic spraying or dip coating), eliminating the need to modify the PPR pipe production line, reducing technology upgrade costs, and making it suitable for large-scale industrial applications.

[0030] In a preferred embodiment, the porous absorbent buffer layer 2 is made of a polymer fiber material with a thickness between 0.5 and 2 mm. The polymer fiber material is hydrophilic, such as polyvinyl alcohol fiber nonwoven fabric. The hydrophilic fiber material can quickly absorb and store excess water droplets, preventing a large amount of condensate from rushing into the guide layer 3 in a short time, thus avoiding poor drainage. It is especially suitable for scenarios where condensate is generated discontinuously, such as air conditioner condensate pipes and steam pipes.

[0031] In a preferred embodiment, the fibers within the porous absorbent buffer layer 2 form interconnected pores. On one hand, this allows for the rapid absorption of water droplets rolling from the superhydrophobic guiding layer 1, buffering the rate of condensation buildup. On the other hand, its hydrophilic properties ensure that even at high condensation rates, water can be temporarily retained, preventing excessive accumulation at the bottom of the pipe. The interconnected pores form a three-dimensional water-guiding channel, allowing water droplets rolling to the porous absorbent buffer layer 2 to quickly diffuse and permeate, preventing saturation and failure of the porous absorbent buffer layer 2 due to localized water accumulation. The interwoven structure between the fibers improves the tensile strength of the buffer layer, ensuring that the porous absorbent buffer layer 2 is not easily broken or deformed even during thermal expansion and contraction of the pipe, guaranteeing functional reliability during long-term use.

[0032] In a preferred embodiment, the pore diameter is between 1 and 10 μm. This pore size range generates significant capillary suction, acting like a "micro straw" to actively attract spherical water droplets 6 from the hydrophobic guiding layer 1, accelerating the transfer of water droplets from the nanolayer to the buffer layer. Even when the pipe is installed horizontally, it ensures that condensate can be promptly removed from the hydrophobic surface. The pore size ensures efficient water conduction while preventing excessively large pores from causing water to directly pass through the porous absorbent buffer layer 2 and impact the flow guiding layer 3, thus balancing the water absorption rate and resistance control. The smaller pore size helps prevent impurities from entering the pores, reducing the risk of pore blockage and extending the service life of the porous absorbent buffer layer 2.

[0033] In a preferred embodiment, the flow-guiding layer 3 is composed of a high-molecular polymer composite. The high-molecular polymer can be simultaneously molded with the PPR pipe through processes such as extrusion and injection molding, eliminating the need for secondary processing, reducing production costs, and ensuring the bonding strength between the flow-guiding layer 3 and the pipe body, preventing delamination. The material composition of the flow-guiding layer 3 enhances its wear resistance and corrosion resistance, ensuring the stability of the hydrophobic layer structure during long-term use and extending the pipe's service life.

[0034] In a preferred embodiment, the thickness of the flow-guiding layer 3 is between 0.1 and 0.5 mm. The low thermal conductivity of the polymer reduces heat transfer from the flow-guiding layer 3 to the outer wall of the pipe, lowering the pipe surface temperature and reducing heat loss and the risk of scalding when transporting hot water or steam. The flow-guiding layer 3 within this thickness range ensures smooth water flow through the flow-guiding groove 4, accelerating the discharge of condensate and reducing the residence time of condensate in the pipe.

[0035] In a preferred embodiment, the flow-guiding groove 4 has a Y-shaped cross-section, and the drain plug is installed on the starting end face of the pipe. The design of the flow-guiding groove 4 allows water permeating from the porous absorbent buffer layer 2 to flow quickly to the water collection area at the bottom of the pipe, accelerating the drainage process. Simultaneously, its nanomaterial components enhance the wear resistance and corrosion resistance of this layer, ensuring the stable performance of the hydrophobic layer structure during long-term use. The drain plug allows for periodic removal and drainage, ensuring the service life of the PPR pipe and solving the problems of condensate accumulation and poor drainage encountered by PPR pipes during use, ensuring long-term unobstructed flow and extending the pipe's service life. The Y-shaped flow-guiding groove 4 allows water permeating from the porous absorbent buffer layer 2 to flow quickly to the water collection area at the bottom of the pipe, accelerating the drainage process and improving drainage efficiency. Through effective drainage design, the problems of condensate accumulation and poor drainage encountered by PPR pipes during use are solved, reducing condensate corrosion of the pipe and improving pipe reliability.

[0036] In a preferred embodiment, when the internal water flow comes into contact with the lotus leaf-shaped protuberance structure 5, it can agglomerate into a spherical shape under the action of surface tension. The water flow agglomerates into a spherical shape on the surface of the lotus leaf-shaped protuberance structure 5, exhibiting a strong rolling tendency, and can quickly detach from the inner wall of the pipe, reducing the residence time of condensate in the pipe and achieving a highly efficient hydrophobic effect. During the rolling process, the spherical water droplets 6 can carry away bacteria and impurities attached to the inner wall of the pipe, reducing bacterial growth and secondary water pollution, and improving the self-cleaning ability of the pipe. Reducing the contact time between condensate and the inner wall of the pipe lowers the probability of chemical corrosion of PPR pipes by chloride ions and oxygen in the water, making it particularly suitable for pipeline systems in humid and hot environments or transporting high-temperature media, thus extending the service life of the pipe.

[0037] Manufacturing process.

[0038] A multi-layer co-extrusion process is used to integrate a hydrophobic layer structure into the PPR pipe manufacturing process. First, nanomaterials are coated on the innermost layer of the PPR pipe mold to form a hydrophobic guiding layer 1. Next, hydrophilic polymer fiber material is rolled into the middle layer mold to form a porous water-absorbing buffer layer 2. Finally, a polymer is applied to the outermost layer mold to create a flow-guiding layer 3. Space is reserved at the corresponding position at the bottom of the pipe for installing a drainage device.

[0039] A hydrophobic guiding layer 1 is installed on the inner wall of the pressure-bearing layer. The hydrophobic protrusions, i.e., lotus leaf-shaped nipple structures 5, reduce the water flow resistance of the pipe, decrease the head loss of the entire system, and indirectly improve energy efficiency. This effectively solves the problem of condensate accumulation in PPR pipes, significantly improving the reliability, durability, and safety of the transported medium. The reduced water flow resistance allows water to be delivered more smoothly to the end user, improving user comfort, especially suitable for long-distance pipeline systems. It also reduces the impact and wear of water flow on the inner wall of the pipe, improving the pipe's durability and reliability, and extending its service life.

[0040] The hydrophobic guiding layer 1 allows water flow to wash away bacteria adhering to the inner wall of the pipe, reducing the possibility of bacterial growth, minimizing secondary water pollution, and improving water quality safety. Through the flushing action of the water flow, the pipe achieves a self-cleaning function, reducing the frequency and cost of manual cleaning and improving pipe maintenance efficiency. It reduces bacterial growth and biofilm formation, lowers the risk of corrosion on the inner wall of the pipe, and extends the service life of the pipe, making it particularly suitable for pipeline systems transporting drinking water or media with high hygiene requirements.

[0041] This pipeline minimizes water flow resistance within the pipe, allowing for smoother water delivery to the end user. This improved efficiency and reliability of the water supply system, making it particularly suitable for scenarios requiring high-flow-rate water supply. Reduced flow resistance also means less energy is needed throughout the delivery process, lowering energy consumption of pumps and other equipment, and improving energy efficiency, resulting in significant economic and environmental benefits.

[0042] Mature manufacturing processes alter the pipe's inner wall structure at a microscopic level without affecting production stability, ensuring high efficiency and consistency in pipe production. This enables large-scale, stable production of high-quality PPR pipes. No major modifications to existing production processes are required; optimization can be implemented directly on existing production lines, reducing technology upgrade costs, increasing production efficiency, and shortening product delivery cycles. Maintaining production process stability ensures consistent pipe product quality, reduces quality issues caused by production process fluctuations, enhances market competitiveness, and strengthens customer trust.

[0043] Through the innovative structural design and meticulous technical implementation described above, the internal hydrophobic self-cleaning structure of this utility model effectively solves the problem of condensate accumulation inside PPR pipes, significantly improving the reliability, durability, and safety of the transported medium of PPR pipes, and providing solid technical support for the widespread application of PPR pipes under various complex working conditions.

[0044] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this utility model.

Claims

1. A hydrophobic, self-cleaning PPR pipe, characterized in that, It includes a hydrophobic guiding layer and a flow guiding layer connected sequentially from the inside to the outside. A porous water-absorbing buffer layer is provided between the hydrophobic guiding layer and the flow guiding layer. Several flow guiding grooves are provided on the surface of the flow guiding layer along the axial direction of the pipe. The surface of the hydrophobic guiding layer is coated with a nanolayer, and several lotus leaf papillae structures are formed on the surface of the nanolayer. Spherical water droplets form point contact with the lotus leaf papillae structures.

2. A hydrophobic self-cleaning PPR pipe as claimed in claim 1, wherein, The condensed water forms spherical water droplets in the nanolayer, and the angle between the spherical water droplets and the tip of the lotus leaf papilla structure is greater than 150 degrees.

3. A hydrophobic self-cleaning PPR pipe according to claim 1 or 2, characterized in that, The thickness of the nanolayer is between 0.05 and 0.2 millimeters.

4. A hydrophobic self-cleaning PPR pipe as claimed in claim 1, wherein, The porous absorbent buffer layer is made of polymer fiber material with a thickness between 0.5-2mm.

5. A hydrophobic self-cleaning PPR pipe as claimed in claim 1 or 4, wherein, The fibers in the porous absorbent buffer layer form interconnected pores.

6. A hydrophobic self-cleaning PPR pipe as claimed in claim 5, wherein, The diameter of the pores is between 1 and 10 μm.

7. A hydrophobic self-cleaning PPR pipe as claimed in claim 1, wherein, The flow-guiding layer is composed of high molecular polymer composites.

8. A hydrophobic self-cleaning PPR pipe according to claim 1 or 7, characterized in that, The thickness of the flow guide layer is between 0.1 and 0.5 mm.

9. A hydrophobic self-cleaning PPR pipe according to claim 1, characterized in that, The flow guide groove has a Y-shaped cross-section, and the drain plug is installed on the starting end face of the pipe.

10. A hydrophobic self-cleaning PPR pipe according to claim 1, characterized in that, When the internal water flow comes into contact with the lotus leaf papillae structure, it can agglomerate into a spherical shape under the action of surface tension.

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