Polyethylene (PE) is a plastic material derived from ethylene, which is manufactured as a blend of polymerized ethylene, antioxidants and carbon black, which infers its characteristic black color to protect it from degradation by solar radiation.
Polyethylene pipes are manufactured by extruding the material. They are more flexible and less fragile than PVC, although in general they are more expensive.
Also PE pipes have less tensile strength than PVC pipes, so for the same nominal diameter and pressure, they must have a greater wall thickness than their PVC counterpart.
There are commercially available three types of PE pipe:
• Low density PE (PE32, LDPE or LPDE), defined by an unpigmented density ≤ 0,930 kg / m3. They are the most flexible of all so they are mainly used for portagoteros branches.
• Medium density PE pipes (PE50B, PEMD, MDPE), with unpigmented density between 0.931 and 0.940 kg / m3.
• High-density PE (PE50A, HDPE, HDPE) with an unpigmented density> 0.940 kg / m3.
The UNE standard that governs this type of pipe is UNE 53367 and UNE 53131. In it it is necessary to distinguish the following concepts:
• Nominal Diameter (DN): is the diameter that theoretically coincides with the outside diameter of the tube
• Nominal Pressure (PN): which is the maximum working pressure at 20 ° C. In this sense, the UNE standard establishes nominal working pressures of 0.4 MPa (4 bars), 0.6 MPa (6 bars) and 1.0 MPa (10 bars)
• Nominal Thickness (e): which is the thickness of the pipe wall.
>> Low Density Polyethylene Tube Catalog for Agricultural Use
Polyethylene low density polyethylene flexible pipes which, as has been seen, contain in their composition parts of antioxidants and carbon black (which infers their characteristic black color), in order to protect the pipe The solar radiation and the rigors of the intemperie, since these branches will run aerial on the surface of the land.
They are supplied rolled in coils, as shown in the attached figure, and are usually marked on the surface of the pipe with a reference that is used to identify it in the following format:
MANUFACTURER - PE32 - 16 - 1.2 - 0.6 - 14 - UNE 53131
Where, the MANUFACTURER indicates the name that identifies the pipe manufacturer
PE32 identifies the kind of material from which the pipe is made
16 is the nominal diameter of the tube which theoretically coincides with the outside diameter, in this case 16 mm.
1.2 is the wall thickness of the tube, in this case 1.2 mm.
0.6 is the nominal pressure, or maximum working pressure for which the pipe is designed. In this case 0.6 MPa (6 bar) of pressure. If the tube is referenced following UNE 53.367 will not include this data.
14 this number will indicate the year of manufacture of the tube (2.014)
UNE 53131 is the reference standard used for the nomenclature that identifies the tube. The UNE standards that govern this type of pipes are UNE 53.367 and UNE 53.131.
The following table lists the most common dimensions for the low density polyethylene hoses used for the portagoteros branches of drip irrigation facilities: