Raw material combined with color masterbatch is first mixed, then fed into the system under vacuum. After raw material drying, it goes through a single-screw extruder and a color line extruder. The molten material is then shaped in a spiral mold, followed by sizing through a sleeve. A spray vacuum setting box helps solidify the shape, and the pipe is cooled in a water tank. An inkjet printer marks the product, which is then transported by a crawler tractor and inspected before packaging. This process results in PPR pipes of various specifications. PPR pipes are specified using a series denoted as "S," along with the nominal outer diameter (dn) and the nominal wall thickness (en). For example, a PPR pipe with S5, dn25mm, and en2.5mm would be represented as S5, dn25×en2.5mm. The series S is a dimensionless number used to define the pipe's size, calculated using the formula: S = (dn - en) / (2 × en), where dn is the nominal outer diameter in mm, and en is the nominal wall thickness in mm. Commonly used PPR pipe series include S5, S4, S3.2, S2.5, and S2. These series are also related to the Standard Dimension Ratio (SDR), which is the ratio of the outer diameter to the wall thickness: SDR = 2S + 1. PPR pipe fittings are typically designed based on the nominal outer diameter (dn) of the connected pipe. The wall thickness of the fitting should not be less than that of the pipe of the same series. Most fittings produced by companies are made for the S2 series, suitable for both hot and cold water systems. PPR pipe pressure ratings vary by series:
- S5 series: 1.25 MPa (12.5 kg/cm²)
- S4 series: 1.6 MPa (16 kg/cm²)
- S3.2 series: 2.0 MPa (20 kg/cm²)
- S2 series: 2.5 MPa (25 kg/cm²) Industrial production of PPR pipes has evolved over time. Traditionally, three methods were used: slurry or suspension processes, bulk polymerization, and gas-phase technology. However, the older slurry method is no longer in use due to its limited range of producible grades. The bulk process uses liquid propylene as a diluent, allowing the polymer to remain insoluble while being suspended in the liquid. Unreacted monomers are removed after the polymer is extracted. The gas-phase method involves gaseous propylene reacting with a solid catalyst in a fluidized bed reactor, offering greater efficiency and control in the production of polypropylene pipes. Grow lights Shenzhen Huangtai Photoelectric Co.,Ltd. , https://www.huangtailed.com