PPR water pipes are generally bonded by hot melt, and the following points need to be paid attention to when connecting.
1. Heating temperature and time
The welding temperature should be controlled at 260-270℃. When the temperature is too low, the PPR pipe cannot be melted in place, and the pipe and fittings cannot be welded well. When the temperature is too high, the PPR pipe will melt too much, so that it is easy to cause blockage at the joint of the pipe or the pipe hole is too small to affect the flow. In addition, PPR will become thin and soft and remain on the die, carbonization will occur under long-term high temperature, which will affect the service life of the die.
Due to the importance of temperature, welding equipment needs to have a good temperature control system. If the temperature control system is not good, the temperature of some welding equipment will be heated to more than 300 degrees. If the temperature is too high, it is easy to cause welding quality problems. .
The heating time is related to the diameter of the PPR tube. For a tube with an outer diameter of 20mm, a heating time of 5s is better, and for a tube with an outer diameter of 25mm, the heating time is 7s. Too short or too long time will affect the welding quality of PPR pipe.
2. Welding depth
The welding depth is related to the outer diameter of the PPR tube. For a tube with an outer diameter of 20mm, the minimum welding depth is 14mm, and for a tube with an outer diameter of 25mm, the minimum welding depth is 15mm.
When the welding depth is too shallow, the welding area is not enough and the water pipe is not firmly bonded. When the welding depth is too deep, the excess part is squeezed inside the pipe, reducing the inner diameter of the water pipe at the squeezed part, resulting in a decrease in the water flow of the water pipe, and even welding blockage. In addition, be careful not to try to rotate pipes and fittings when inserting them.
3. Is the die head worn?
There is a layer of coating containing Teflon on the die of the welding machine. Teflon is a difficult-to-stick material. Most glues on the market have no bonding effect on it. It can effectively prevent PPR from remaining during welding. On the die. The quality of the die is good or bad, but the die must be kept clean. It is worth noting that Teflon will wear out after being used for a long time. After wear, the anti-sticking characteristics of the die will be affected to a certain extent. At this time, the die needs to be replaced, otherwise it will cause the PPR pipe to fall off. Danger of welding. Nowadays, many plumbers are reluctant to change the die head. In fact, it is only a few dollars or even a few dollars. For this reason, it is really not worth it because of small losses.
4. PPR raw materials are good or bad
The quality of the raw materials of the water pipe will affect the weldability of the water pipe. I believe that experienced plumbers know it well. 260-270℃ is the welding temperature of PPR, which means that PPR material melts sufficiently at this temperature and is easy to weld. Here are two concepts of popular science, melting range and melting index. For polymer materials, the melting temperature is a range, that is, the melting range (initial melting-final melting), and the fluidity after melting can be expressed by melting index. How do these two parameters affect welding? It can be simply understood that if the initial melting point is lower, the material will melt faster, and the higher the melting point, the thinner the material will melt. These two characteristics directly affect the operation time of PPR pipe welding.
The key technology of PPR raw material is here. The two parameters of good pure PPR raw material are better controlled, and the pipeline is easier to weld. The melting range and melting index of the PPR raw material doped with impurities will become larger, which will ultimately affect the weldability of the PPR pipe.
5. Whether the water pipe port is cracked
Due to the low temperature brittleness of PPR, especially in winter, the environment of the construction site is often more complicated. If you do not pay attention to protection, the PPR pipe will inevitably be damaged. It is necessary for plumbers to check whether the pipes have been damaged before welding the pipes, and avoid using pipes with cracked ports to weld with pipe fittings, which may cause water leakage. In addition, pay attention to the cleanliness of the welded part of the pipe to avoid weak welding.