Aluminum-plastic pipes are a common choice for solar water heaters
Aluminum-plastic pipes have the characteristics of corrosion resistance, high strength and high temperature resistance /strong>, and have along lifespan. In addition, aluminum-plastic pipes also have good sealing properties and can effectively prevent water leakage. In comparison, although copper tubes have better thermal conductivity, they are relatively expensive and easily corroded. PVC pipes, on the other hand, do not withstand high temperatures and are prone to aging and deformation. Therefore, from the point of view of cost/performance and practicality, it is a good choice to use aluminum-plastic pipes for solar water heaters. Of course, when purchasing aluminum-plastic pipese, you must also choose products of reliable quality to guarantee effectiveness and safety.
Since the solar water heater is installed outdoors, it is recommended to use aluminum-plastic pipes.
1. The low temperature resistance of aluminum-plastic pipes is higher than that of PPR pipes. PR is fragile when cold (the fragility point is -20°C), special care is therefore required during construction in winter (below 5°C). Aluminum-plastic pipes have no cold brittleness (the brittle point is -70°C) and can be easily installed below -20°C.
2. The expansion coefficient of PPR pipes is high. Since the piping system is rigid and straight, the PPR pipe itself cannot digest the deformation, so it is easy to cause bending, deformation and leakage of the piping system. Aluminum pipes are composed ofaluminum. Taken together, their linear expansion coefficient with aluminum is approximately 0.025 mm/m.
The temperature is ℃, which is 1/6 of the PPR pipe. Affected by temperature changes, the deformation is small, while the aluminum pipe is a flexible coil. The hose itself can absorb a certain amount. deformation and will not cause thermal deformation of the piping system.
3. PPR pipe has poor aging resistance. The PPR molecular chain structure - (-CH2—CH-)n- contains a large number of unstable tertiary carbon atoms, which are more sensitive to CH3 light and oxygen. , and impurities (such as copper, iron ions) and aging. Therefore, the PPR product manual generally stipulates that the open air stacking time should not exceed six months.
PE plastic used in aluminum-plastic composite pipes has a cha structuremolecular chain - (-CH2-CH2-)n-, which is the most stable structure among plastics, and the aluminum layer in the middle of the aluminum-plastic pipe insulates the inner and outer layers, the outer layer in plastic can add sufficient stabilizers to resist aging by light and oxygen without affecting the hygiene of the inner layer that comes into contact with water.
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Advantages of aluminum-plastic pipes
< p >Aluminum The advantages of plastic pipes can be summarized in the following three aspects:1. Excellent hygienic performance: The outer layer of aluminum-plastic pipes is made of special polyethylene material, which is clean and non-toxic. toxic. More importantly, the middle layer of the tube is made of aluminum, which not only insulates light but also blocks oxygen. It is goodIt is known that the environment in which microorganisms grow requires light oxygen. The aluminum core layer of the aluminum pipe will eliminate the growth of microorganisms and algae that plastic pipes cannot colonize.
Not only do plastic pipes contain high amounts of antioxidants, which prevent material degradation, but when the antioxidants are extracted from the water held in the pipes, they can also cause water pollution. the water. In addition, because there is no photoresistant material in the entire plastic pipe, microorganisms are easily generated, causing secondary pollution of water quality.
2. Excellent high and low temperature resistance: the long-term use temperature is 95°C (50 years, IMPa), the maximum use temperature is 110°C, and the aluminum plastic pipe has a low d coefficiente thermal expansion. . It is equivalent to the thermal expansion coefficient of aluminum and only one-sixth of the total number of plastic pipes. When the temperature changes, the deformation is very small and the aluminum plastic pipe is a flexible coil. The pipe itself can absorb a certain amount of deformation and will not cause thermal expansion deformation of the piping system.
The whole plastic pipe has poor high and low temperature resistance. The long-term use temperature of PPR is only 70 degrees (50 years, IMPa), and the maximum use temperature is 95 degrees. At the same time, the expansion coefficient of PPR pipes is high, and when the external water temperature (hot and cold water) changes, a large initial deformation occurs. Since PPR pipes are straight and rigid pipes, they cannot absorb deformation, resulting inut easily cause the system to bend, warp, or even leak.
3. Long service life: PE plastic multi-tube aluminum mold, the molecular chain structure (CH2 - CH2 -) used is relatively stable in the plastic, and. As an insulation layer between the inner and outer aluminum layers of the tube, plastic can be added to the outer layer to repel light stabilizers and oxygen aging without affecting the hygiene of the internal contact with water, thus improving its anti-aging performance.