In recent years, PPR tubes in China have developed rapidly, but the product quality in the market is uneven, and there is a phenomenon of fish dragon mixing beads. Whether the cold water pipe or the hot water pipe, the material of the pipe should be the same, but the wall thickness of the cold and hot water pipe is different. However, at present, it is common in the market that better raw materials are used for pipe fittings and hot water pipes, while ppb (ppb is block co polypropylene) is used for cold water pipes to impersonate PPR. In this case, due to different materials, the welding joint is very prone to fracture, desoldering, leakage and so on.
When purchasing, consumers should pay attention to the identification on the pipe. The product name should be "random copolymerized polypropylene pipe for cold and hot water" or "PP-R pipe for cold and hot water", and there is an explicit national standard "GB / t18742-2002". Attention shall be paid when products are identified with other names or other standards.
Generally speaking, the hot water pipe should use the pipe with pipe series s less than 2.5, that is, the wall thickness of the pipe with outer diameter of 20 should be more than 3.4mm, and the wall thickness of the pipe with outer diameter of 25 should be more than 4.2mm. In addition, the linear expansion coefficient of PPR pipe brand price is about 10 times that of copper pipe, so it should be noted that there is room for expansion and contraction during construction and installation.
Copper tube: the chemical properties of copper are quite stable and not easy to be corroded. The strength of copper pipe is much higher than that of plastic pipe, which can withstand considerable pressure; Compared with steel pipes, copper pipes have good toughness and do not crack or break under strong frost heave and impact. Copper has a high melting point and can work safely for a long time even if the transmission medium temperature is as high as 200 ℃. Copper pipe has good impermeability. In the process of use, its surface can form a protective film with dense structure and not dissolved by the medium. No matter oil, carbohydrate, bacteria and viruses, harmful liquid, oxygen or ultraviolet light can pass through it and erode the pipe wall.
The connection methods of copper pipes are mainly divided into two categories: mechanical connection and brazing connection. Mechanical connection is divided into ferrule type, plug-in type and crimping type.
Ferrule connection is a relatively simple construction method. It is easy to operate and master. It is a common connection method in construction. During connection, as long as the end face of the pipe notch can be perpendicular to the pipe axis, the burr at the notch shall be cleaned, the position of the snap ring shall be placed correctly during pipe fitting assembly, and the nut shall be tightened, the tight connection of the copper pipe can be realized.