What are the commonly used non-metallic pumps?
Compared with steel, the physical properties of non-metals are usually much worse, even inferior to aluminum and brass. However, by increasing the section modulus of the component (that is, increasing the wall thickness) and adding ribs, non-metals can withstand a certain amount of work Non-metallic pumps commonly used for pressure include plastic pumps, ultra-high molecular weight polyethylene pumps, glass fiber reinforced plastic pumps, rubber-lined pumps, ceramic pumps, graphite pumps, etc.
1. Plastic pump
With the rapid development of the plastics industry, the variety of plastic pumps is increasing, and more and more non-metallic pumps are being replaced. See the following for the varieties of plastic pumps.
(1) Fluorine plastic pump
①F46 pump polyperfluoroethylene propylene (FEP) is a modified type of polytetrafluoroethylene. It is made by the suspension method of tetrafluoroethylene and hexafluoropropylene at 55~60℃. It is commonly known as F46. F46 has excellent mechanical properties. , Chemical stability, weather resistance, electrical insulation and flame retardancy, low surface tension, good adhesion to metal in the molten state, this material can be used for a long time at a temperature of -85~205℃. The use temperature of the pump made of this material can reach 150℃.
②Fluorine alloy pump The fluoroplastic alloy developed by the Shanghai Institute of Organic Chemistry is made by using the existing domestic ultra-high molecular weight polyperfluoroethylene propylene as the main raw material, directly blending with tetrafluoroethylene and filler, and using physical methods. Fluoroplastic alloy is a new type of material developed in recent years. It has the excellent properties of fluoroplastic, high temperature resistance, corrosion resistance, good electrical insulation and non-stick surface. This product has obtained a national invention patent, the patent number is 851009
The characteristics of fluorine plastic alloy are: fluorine plastic alloy F50-1, high temperature resistance is better than fluorine plastic F46, and the cost is cheaper than F46. In many applications, it can replace F46. Fluorine plastic alloy F502 has the excellent performance of PTFE F4 (Long-term use at 250℃, resistance to various acids, alkalis, strong oxidants and organic solvents, good electrical insulation, etc.), and overcomes the shortcomings of F4's easy cold flow and poor workability. It can be hot-pressed or cold-pressed and sintered, cost-effective Between polytetrafluoroethylene suspension powder and dispersion powder, it can replace polytetrafluoroethylene in many applications. The use temperature of the pump made of this material can reach 150℃
③The temperature range, mechanical properties, and corrosion resistance of the soluble polytetrafluoroethylene (PFA) pump are roughly equivalent to F46
④Pure PTFE pumps and chlorotrifluoroethylene pumps. Pure PTFE plastics have poor manufacturing technology, high cost and cold flow properties, so they are generally not suitable for pumps made of this material. Polychlorotrifluoroethylene (PCTFE), commonly known as F3. Its processing technology and corrosion resistance are good, but the temperature resistance is low.
⑤Polyvinylidene fluoride (PVDF) pump Polyvinylidene fluoride (PVDF) is the rising star of the fluororesin family. Polyvinylidene fluoride is made by free radical polymerization of vinylidene fluoride, and its molecular weight can be as high as 10. PVDF has excellent machinery. It has high mechanical strength among fluoroplastics at present. It has excellent chemical stability and weather resistance. Its biggest feature is corrosion resistance, impact resistance, aging resistance, and creep resistance. It can be used for general thermoplastics. The plastic processing method is shaped and easy to process, which is far less than the performance of other fluoroplastics. Except for concentrated sulfuric acid, concentrated nitric acid and a few organic solvents, it can withstand more corrosive media. The abrasion resistance is second only to ultra-high molecular weight jujube ethylene, better than other plastics. The temperature resistance is also good, the use temperature of the pump made of this material can reach 120℃. PVDF plastic has good overall performance and is a promising engineering plastic for pumps.
(2) Ultra-high molecular weight polyethylene pump
Ultra-high molecular weight polyethylene is the latest international engineering plastic for pumps. The American Society for Testing and Materials (ASTM) stipulates that its linear polyethylene with a molecular weight of 3-6 million is called ultra-high molecular weight polyethylene. Because of its extremely long molecular chain, It has many unique physical and mechanical properties, corrosion resistance exceeds other existing thermoplastics, low surface friction coefficient, good low temperature impact resistance, excellent environmental stress crack resistance, good cold resistance, and non-toxicity (see Table 2-49, Table 2-50). However, its processing requirements are high, and it can only be processed by pressing and sintering. Extrusion and injection technology are already being developed abroad. At present, the raw materials are mainly imported, with stable quality and high cost. The quality of the domestic trial-produced raw materials is not stable enough, and the molding process performance data needs further exploration.
UHMWPE new high-performance engineering plastic pump is particularly suitable for transporting corrosive media containing fine particles, but the temperature resistance is not high, the pump made of this material allows the use of 80C
