Most gasoline engines are now equipped with PCV valves (crankcase forced ventilation) to promote engine air exchange, but the pollutants in the gas will be deposited around the PCV valve, which may make the valve clogged. If the PCV valve is clogged, the contaminated gas flows into the air filter in the reverse direction, contaminating the filter element, so that the filtering capacity is reduced, resulting in increased fuel consumption, engine wear and tear, and even damage to the engine. Therefore, regular maintenance of the PCV is required to remove contaminants around the PCV valve. [Edit paragraph] PCV valve source and function of each car has an exhaust pipe will engine combustion exhaust out of the car, but there is no way to exhaust 100% out, there will still be a small portion of the combustion of exhaust gas by the piston and the cylinder wall gap drilled into the oil pan, once the oil into the oil pan of the oil accumulation of gas, can not be excluded, then the formation of air pressure, not only dilute the oil, resulting in the engine parts of the lubrication This will not only dilute the oil and cause poor lubrication of the engine parts, but will also cause abnormal oil consumption and other serious consequences. Therefore, the oil and gas in the oil pan must have a drain pipe. In the past, before the legislation on automobile exhaust pollution control, the oil and gas were all connected to a pipe from the oil pan, allowing the oil and gas to be discharged directly into the atmosphere. The older the car, the more serious the combustion of oil and gas leakage, the more exhaust gas from the oil pan will be discharged, forming a serious air pollution.
From the 60's, in the United States, California has taken the lead in requiring cars to be equipped with PCV systems, so PCV can be said to be the oldest smoke pollution control system. It has a control valve connected to one end of the engine intake pipe, one end connected to the oil pan, so that after the engine start running, the vacuum generated by the intake air can be sucked out of the oil pan in the oil, so that it is with the fresh air into the cylinder together with the burning and to solve the pollution problem. [Edit] PCV valve working process of the earliest use of the crankcase forced ventilation system for the open system, this system is only in the intake pipe and the crankcase between the addition of a ventilation pipe with a PCV valve. The working process is: the outside world under the action of fresh air in the intake vacuum, through the oil port cover and other places in the atmosphere connected to the vent into the crankcase and the crankcase in the gas mixture, through the PCV valve is sucked into the intake system into the combustion chamber combustion. This system has a simple structure, easy to install and maintain, but in some working conditions can not be all the crankcase gas into the intake system, especially under large loads, the crankcase gas increase, the intake pipe vacuum can not be all the gas into the intake system, part of the gas from the oil cover into the atmosphere, resulting in pollution of the environment. Improvements to the open system to form a closed crankcase ventilation system. This system is based on the open system sealed crankcase, in the air filter and carburetor (EFI engine throttle body) between the increase in a crankcase connected to the ventilation pipe, the fresh air through the air filter, ventilation pipe into the crankcase with the gas mixing in the intake pipe under the action of the vacuum through the PCV valve into the cylinder for combustion. When the engine is working under a heavy load, the excess air will enter the back of the air filter through the ventilation pipe and mix with the engine intake air to enter the cylinder for combustion. The closed system, which does not allow the exhaust gas to the atmosphere, but also allows fresh air to be used for crankcase ventilation, is now commonly used in the world. [edit]PCV valve working principle PCV valve is a metering control valve. Installed in the engine crankcase ventilation system and air intake system between the PCV valve by the vacuum to control, regulate the crankcase ventilation system produced by the soot into the air intake system flow, when the engine is running at high speeds when the flow to be higher than at low speeds, at the same time, when the engine backfires, the PCV valve should be able to cut off the ventilation to prevent the crankcase from exploding.... [edit]PCV devicePCV is an abbreviation for PositiveCrankcaseVentilation (crankcase forced ventilation). It serves to prevent fugitive gases from entering the atmosphere, as well as preventing oil deterioration. At the end of the engine's combustion process, some unburned mixture leaks from the piston rings into the crankcase under high pressure, a leak known in the industry as "flue gas". This leakage is referred to in the industry as "flue gas". This flue gas escapes from the crankcase into the atmosphere and causes pollution. This mixture is not eliminated, but it also dilutes the oil in the crankcase, which degrades the oil and causes premature wear and tear of the engine parts.
PCV device mainly consists of ventilation hose, PCV valve. A ventilation hose is generally connected to the air filter to the valve cover, another connected to the PCV valve to the intake manifold. PCV valve consists of a plunger-type valves and springs, located in the intake manifold side of the intake manifold, the intake manifold vacuum determines the degree of opening and closing of the PCV valve and the degree of opening and closing and opening of the PCV valve and the degree of the decision to run out of gas mixture was re-inhaled into the intake manifold to participate in the combustion of the number of.
In other words, when the engine is running at normal speed or at a slower RPM, the air flow is small and the flue gas is less, the PCV valve is less open or even closed, and the flue gas that is forced into the combustion is less or even non-existent. When the engine accelerates or the speed is high, the gas flow is large, the gas is also large, the PCV valve opening is larger, so the gas is forced into the combustion is also more. [Edit] Inspection method Make the engine idle, remove the PCV valve from the cylinder head cover hose, check whether the PCV valve is clogged. If you put your hand on the PCV valve interface, your fingers can feel a strong vacuum suction.
Another way to check is to install the PCV valve back from the air filter after removing the crankcase intake tube, with a piece of paper gently covered in the mouth of the tube, to be in the crankcase when the pressure decreases (about lMIn after), it should be obvious to see the thin paper is sucked to the mouth of the tube. In addition, after stopping the engine running, remove the PCV valve hand shaking check, if you hear a "click" sound, that the PCV valve is flexible available. [edit paragraph] Polyvinylchloride (Polyvinylchloride, PVC) Polyvinylchlorid, the main component of polyvinyl chloride polyhydroethylene, bright color, corrosion-resistant, strong and durable, due to the increase in the manufacturing process of plasticizers, anti-aging agents, and other toxic auxiliary materials to enhance its heat resistance, toughness, ductility, etc., so its products are generally not Store food and medicine. It is a favorite, popular and widely used synthetic material in the world today. Its global usage is the second highest among all kinds of synthetic materials. According to statistics, in 1995 alone, the production of PVC in Europe amounted to about 5 million tons, while its consumption was 5.3 million tons. In Germany, the production and consumption of PVC averaged 1.4 million tons. PVC is being produced and applied worldwide with a growth rate of 4%. In recent years, the growth rate of PVC has been particularly significant in Southeast Asia, where there is an urgent need for infrastructure development. In the production of three-dimensional surface film material, PVC is the most suitable material. PVC (polyvinyl chloride), the monomer of the structural formula for the CH2 = CHClpvc
PVC material is extremely wide range of uses, mainly used in the production of: PVC card; PVC labeling; PVC wire; PVC curtains; PVC coated welded wire mesh; PVC foam panels, PVC ceiling, PVC skirting, water pipes, PVC, and other PVC materials. water pipes, pvc skirting, etc., as well as threading pipes, cable insulation, plastic doors and windows, plastic bags and other aspects. PVC products can be found everywhere in our daily life. pvc is used to make all kinds of imitation leather, used for luggage, sports products, such as basketball, soccer and rugby etc. It is also used to make uniforms and special protection. It is also used to make uniforms and belts for specialized protective equipment. PVC material is extremely versatile and has good processing performance, low manufacturing cost, corrosion resistance, insulation and other good characteristics.
There are many types of pvc cards in Previn, there are ordinary pvc cards (calendar card, souvenir card, membership card, discount card, VIP card, points card, magnetic stripe card, dining card, scratch card, smart card, door opener card, gold card, silver card, attendance card, souvenir card, membership card, discount card,), frosted pvc card, clear pvc card, transparent frosted pvc card, and so on. The product has pvc card is printed by the printing machine so the card has color diversity and bright color effect of the pattern and other characteristics.
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Previn PVC card
Coiled pvc flooring
pvc ceiling
pvc card
pvc curtains Analysis of the factors affecting the price of the PVC market: The price of any commodity is ultimately determined by its supply and demand, PVC is no exception. Whether it is the cost of upstream raw materials, national policies and macroeconomic factors, are by affecting the supply and demand for PVC, to affect the price. 1, the impact of upstream raw materials At present, the PVC industry into the era of high-cost support has been undoubtedly, the industry's profits are greatly compressed, the price of goods at this time will usually be not much difference with its production costs, and, PVC production process route has a number of relatively low-cost process routes, the price of raw materials will be more impact on the price of PVC. Such as 2005 - the first half of 2008, oil prices have been running high, low production costs of calcium carbide PVC preparation process, due to the domestic mainly calcium carbide-based materials, resulting in PVC prices did not synchronize with ethylene, crude oil prices. By the same token, the second half of 2008 to date, due to coal production restrictions to protect the price, the cost of calcium carbide has been high, while the price of crude oil is low, resulting in low production costs of ethylene PVC, at this time, the market supply of PVC is mainly ethylene-based materials, calcium carbide companies to adjust their own operating rate according to the price of high and low, to supplement the market supply. Therefore, in this part of the PVC production costs, the main factors affecting the price should be considered coal, coke, electricity, calcium carbide, crude oil, ethylene, VCM and other price costs, in addition, the price of raw salt will also be through the value of chlorine conduction on the price of PVC to a certain extent. (1) Coal, coke, electricity As China's industrial electricity is still mainly thermal power generation, coke is also mainly from coal, so the prices of the three are basically bound to be analyzed uniformly here. According to the preparation cost of calcium carbide PVC, tons of PVC equivalent power consumption of about 7,000 degrees, equivalent to coal consumption of about 3 tons, energy costs accounted for more than 50% of the proportion of production costs, therefore, coal, coke, electricity and other energy price fluctuations will have a direct impact on the market price of PVC. At present, China's coal industry to implement production restrictions to protect the price, which is not only on China's calcium carbide PVC production costs is a strong support, and some companies may turn to sell coal raw materials directly, rather than further processing for PVC and then sold, thus affecting the supply of calcium carbide method of PVC, and further enhance the price of PVC, until PVC can reach a reasonable price. (2) crude oil, ethylene, vinyl chloride, ethylene dichloride From the world, the production of PVC is still dominated by the ethylene method, at present, China's PVC is mainly based on the calcium carbide method is dominated by one is to benefit from the low cost of calcium carbide method of the previous period, and the implementation of anti-dumping on foreign PVC and the high price of crude oil run. Now with the fall in crude oil prices, as well as the expiration of China's foreign implementation of anti-dumping, imported materials have begun to impact the domestic market. Although the efforts of the relevant associations, China's foreign implementation of anti-dumping policy of PVC to be temporarily extended for a year, but crude oil prices below $ 50 continued to run low, even if we are in the imported materials levied a higher anti-dumping duties, there are still some of the imports of large quantities of material influxed into the Chinese market, according to statistics, in December 2008, a month of imported PVC accounted for the year's total imports of 70%. Therefore, crude oil, ethylene and imports of vinyl chloride (VCM) and ethylene dichloride (EDC), the price of high and low, but also directly affect the price trend of PVC. In addition, because our country only on foreign PVC anti-dumping, and VCM and EDC did not implement the protection policy, some domestic PVC manufacturers may directly from abroad a large number of low-priced purchase of VCM polymerization into PVC, so, crude oil and VCM and other downstream product prices will have a direct impact on the domestic price of PVC. (3) Raw Salt The main consumption area of raw salt is the production of chlor-alkali products. The chlorine generated from the electrolysis of raw salt is partly used in the production of PVC and other chlorine products, and the sodium is partly used in the production of soda ash and caustic soda. Although chlorine is not a major factor in the production cost of PVC, the sodium part is the main cost of caustic soda and soda ash. Therefore, the price of raw salt will directly affect the price of alkali products, and affect the market demand for alkali products, and there is a chlorine-alkali balance between PVC and alkali, which indirectly affects the supply of PVC, thus affecting its price trend. 2, factors affecting the downstream demand for PVC (1) real estate industry According to the stage of development of the industry, PVC has entered the maturity period, with obvious buyer's market characteristics, therefore, the downstream demand at this stage of the impact of commodity prices is particularly important. the largest consumer of PVC is profiles, profiles and pipes, mainly used in the construction sector, so the future development of the domestic real estate market dynamics on the demand for PVC plays a decisive role. PVC demand plays a decisive role. In addition, China is currently in the process of rural urbanization, some infrastructure investment will also have a certain role in pulling the consumption of PVC, but due to foreign developed countries have completed this process, the demand for PVC has basically reached saturation, coupled with the spread of the financial crisis, the decline in purchasing power of the international market, the real estate industry is in the cycle of the trough, do not rule out the possibility of a large number of imports from abroad into the country will be on the Domestic market prices have a certain impact. (2) Domestic economic trends There are already data showing that the growth rate of GDP is a strong support for the price of PVC, so the future economic trends in the country will directly affect the price of PVC. In order to cope with the impact of the international financial crisis, China's government to implement the 40,000 billion economic stimulus plan, aimed at safeguarding the domestic economic growth, mainly invested in infrastructure and agricultural construction, which may stimulate the domestic market for PVC digestion capacity. (3) the export of plastic products In addition to profile pipe, PVC is also widely used in the field of plastic containers, toys and other products such as packaging and daily necessities (such as rubber shoes, soles, ponchos and sporting goods). According to statistics, China's annual foreign exports of 6.8 billion pairs of shoes, 50% of home appliances for export, the export of these plastic products will also have a certain impact on the demand for PVC. 3, the impact of national policies (1) petrochemical industry revitalization plan At present, the State Council considered and adopted in principle the petrochemical industry and light industrial restructuring and revitalization plan, decided to increase credit support for petrochemical enterprises, will stop approving the pure expansion of production capacity of coke, calcium carbide and other coal chemical projects, accelerate structural adjustment, optimize industrial layout. Restrictions on coal chemical industry and support for the crude oil petrochemical industry, it is reported that there will be 600,000-800,000 tons of large ethylene projects will be put into operation, which may have a certain impact on the production structure of China's PVC, thus changing the current PVC pricing mechanism. (2) Energy saving and emission reduction industry access conditions Energy saving and emission reduction has always been the top priority of China's government work, PVC industry is a typical high-energy industry, in order to optimize the industrial structure, China's chlor-alkali industry to implement the new access conditions for 22 high-energy products to implement the maximum energy consumption restrictions and minimum energy utilization, of which calcium carbide, PVC, caustic soda and so on are in the scope of the limitations, which will have an impact on the supply of PVC in a specific period of time. This will have an impact on the supply of PVC in a specific period of time. In addition, the Energy Conservation Act also provides for building energy efficiency, according to statistics, PVC plays an important role in the energy saving of window frames in Europe, which can help family houses save 1 billion euros in heat costs each year, so with the depth of China's energy conservation work, the future of our country may have further demand for PVC energy-saving window frames. (3) export tax rebate rate and export restrictions on processing trade In 2007, China's export tax rebate rate of PVC from 11% directly down to 5%, as China's PVC exports itself is to rely on price advantage, so the downward adjustment of the export tax rebate rate as well as export restrictions on processing trade, will further compress the profitability of export products, weakening the export enthusiasm of PVC manufacturers, aggravating China's PVC Supply exceeds demand situation, especially those who produce PVC through the import of VCM and EDC and then processed for export. (4) anti-dumping policy anti-dumping on China's PVC price trend can be elaborated from two parts, one is China's PVC from South Korea, Japan, the United States and Russia and other foreign countries to implement anti-dumping policy, through the imposition of high anti-dumping duties will be rejected out of the country, so as to stabilize the supply structure of the domestic PVC in a particular historical stage; In addition, China's current PVC supply exceeds demand in a very serious situation. Work rate has been reduced, is a net importer to exporter, but foreign countries at the same time will be for the protection of their own industry considerations, the implementation of anti-dumping on China's exports of PVC, such as India, Turkey's special protection policy, etc., which is bound to make China's exports of PVC blocked, thus affecting the domestic supply and demand relations. 4, the impact of other related areas of commodities (1) the impact of the soda ash industry China's PVC production is mainly based on the calcium carbide method, in the production of PVC at the same time, usually produces the equivalent quality of alkali, in the case of low demand for PVC, the start rate of the situation is not enough, the alkali production will also be lowered, thus changing the alkali supply and demand relations. By the same token, the price of alkali as well as the economic development of alkali demand will also react to the supply of PVC. (2) The impact of the oil refining industry The entire oil refining industry is a systematic project, in the refining of gasoline, diesel and other refined oil at the same time, but also get ethylene and other chemical raw materials, so if due to the global economic downturn, resulting in the reduction of demand for refined oil, but also reduce the production of ethylene, thus affecting the supply of PVC of ethylene method. Chemical and Physical Properties:
Rigid PVC is one of the most widely used plastic materials.
The melting temperature of PVC during processing is a very important process parameter, if this parameter is not proper it will lead to the problem of material decomposition. The flow characteristics of PVC are quite poor and its process range is very narrow. Especially large molecular weight PVC material is more difficult to process (this material usually need to add lubricants to improve the flow characteristics), so usually use small molecular weight PVC material. The shrinkage of PVC is quite low, generally 0.2 to 0.6%. Injection Molding Process Conditions Drying Treatment: Drying treatment is usually not required.
Melting Temperature: 185~205℃ Mold Temperature: 20~50℃
Injection Pressure: up to 1500bar Holding Pressure: up to 1000bar Injection Speed: In order to avoid degradation of the material, the injection speed should be fairly high.
Runners and gates: all conventional gates can be used. For smaller parts, it is best to use a pin-tip or dive-in gate; for thicker parts, it is best to use a fan gate. The minimum diameter of the needle tip or submerged gate should be 1mm; the thickness of the fan gate should not be less than 1mm.
Typical use: PVC has the outstanding features of abundant raw materials (petroleum, limestone, coke, salt and natural gas), mature manufacturing process, low price, wide range of uses, etc., and has now become the world's second largest general-purpose resin after polyethylene resin, accounting for 29% of the total consumption of synthetic resins in the world. It has become the second largest general-purpose resin in the world after polyethylene resin, accounting for 29% of the world's total consumption of synthetic resin. PVC is easy to process and can be processed by molding, laminating, injection molding, extruding, calendering, blow molding hollow and so on. PVC is mainly used for the production of artificial leather, film, wire sheathing and other plastic soft products, water supply pipes, household pipes, housing wall panels, commercial machine shells, electronic product packaging, medical equipment, speedboat fenders, but also for the production of plates, doors, windows and valves and other plastic hard products.
PVC can be divided into hard PVC and soft PVC, of which hard PVC accounts for about 2/3 of the market, soft PVC accounts for 1/3. soft PVC is generally used for floors, ceilings, and the surface layer of leather, but due to the soft PVC contains softeners (which is also the difference between soft PVC and hard PVC), it is easy to become brittle, not easy to store, so its scope of use is limited. Hard PVC does not contain softener, so it is flexible, easy to mold, not easy to brittle, non-toxic and non-polluting, long preservation time, so it has great development and application value. Below are referred to as PVC. soft PVC is mostly used to make vacuum blister film, used for all kinds of panels of the surface layer of the packaging, so it is also known as decorative film, adhesive film, used in building materials, packaging, medicine and many other industries. The building materials industry accounted for the largest proportion of 60%, followed by the packaging industry, there are a number of other small-scale application of the industry.
Simply put, an aqueous solution of salt undergoes chemical decomposition by the action of an electric current. This process produces chlorine, caustic soda and hydrogen. Refining and cracking oil or gasoline produces ethylene. When chlorine and ethylene are mixed, vinyl dichloride is produced; vinyl dichloride, in turn, can be converted to produce chlorinated vinyl, which is the basic component of polyvinyl chloride. The polymerization process joins the chlorinated vinyl molecules together to form the PVC chain. Polyvinyl chloride produced in this way is in the form of a white powder. It cannot be used alone, but it can be mixed with other components to produce many products.
Vinyl chloride was first synthesized in 1835 in the laboratory of Justus von Liebig. And polyvinyl chloride was synthesized by Baumann in 1872. But it wasn't until the 1920s that the first commercial products of PVC were produced in the United States, and within the next two decades large-scale production began in Europe.
PVC has the advantages of flame retardancy (flame retardancy value of more than 40), high chemical resistance (resistance to concentrated hydrochloric acid, concentration of 90% sulfuric acid, concentration of 60% nitric acid and concentration of 20% sodium hydroxide), mechanical strength and good electrical insulation. However, its heat resistance is poor, the softening point of 80 ℃, at 130 ℃ began to decompose and discoloration, and precipitation of HCI. PVC characteristics and molding properties Specific gravity: 1.38 g / cm3, molding shrinkage: 0.6-1.5%, molding temperature: 160-190 ℃.
Features: mechanical properties, excellent electrical properties, acid and alkali resistance, chemical stability, but the softening point is low. Suitable for the production of sheet, wire and cable insulation, seals and so on.
Molding characteristics:
1. Amorphous material, small moisture absorption, poor fluidity. In order to improve the fluidity, to prevent the occurrence of air bubbles, the plastic can be pre-dried. The mold casting system should be thick and short, the gate cross-section should be large, there should be no dead ends. The mold should be cooled and the surface should be chrome plated.
2. Because of its corrosive and fluidity characteristics, it is best to use special equipment and molds. All products should be added with different kinds and quantities of additives according to the needs.
3. It is easy to decompose, and is more likely to decompose in contact with steel and copper at a temperature of 200 degrees Celsius. It is easy to decompose when it comes in contact with steel and copper at 200 degrees Celsius, and when it decomposes, corrosive and irritating gases will be released. Irritating gases are emitted during decomposition. Small molding temperature range.
4. Screw injection machine nozzle, the aperture should be large, in order to prevent dead-end stagnant material. Good not with inserts, such as inserts should be preheated. What is the pollution of PVC PVC pollution causes:
PVC some toxic additives and plasticizers, may be leaking or gasification; part of the additives will interfere with the biological endocrine (affecting reproductive function), some can increase the risk of cancer; incineration of PVC waste will produce carcinogenic dioxin and pollution of the atmosphere.
Conventional PVC materials, such as wires and cables, are a serious source of pollution. In the manufacture, use and disposal, will produce a large number of dioxin, chlorohydrochloric acid, lead and other harmful substances; PVC material combustion will occur when a very large smoke, and produce harmful HCL gas; and most of the PVC material contains Pb (lead), Cd (cadmium), etc. (used as cable stabilizers) a variety of harmful heavy metals, which will cause some harm to human health; incineration or burial, will cause Pollution of soil and water.
Since most disposable medical device products are made of medical-grade polyvinyl chloride (PVC) or polycarbonate (PC), the thermal decomposition of PVC during processing has a strong corrosive effect on steel, and PC has high hardness and high viscosity, so the material requirements for the parts of the plasticizing part must be corrosion-resistant, anti-abrasive, and have a high degree of polishing performance. At present, most of the medical injection molding machine using barrel screw hard chrome plating method or stainless steel as the material to produce machine screw to achieve the above special requirements. In addition, in order to prevent the thermal decomposition of PVC processing gas, the requirements of the dynamic fixed template surface aluminizing treatment, but also on the periphery of the plate gold aluminizing treatment or stainless steel plate production of plate gold, plate gold seams using non-toxic silicone sealing, in order to prevent the plastic processing of gas to the outside (plastic processing of gas can be centralized through a special device and then after purification and treatment can be released into the atmosphere). (The gas generated during plastic processing can be collected centrally by special equipment and then purified before being discharged into the atmosphere).
Hazards of DEHP, a common additive in PVC: Because DEHP (di-phthalate) is easily atomized, other vinyl products, including automobile interiors, shower curtains, or floor coverings, also release toxic gases into the atmosphere, and DEHP is easily dissolved in oily liquids. There are also emerging safety concerns about additives leaking out of these soft plastic toys if children chew on them. Some studies suggest that this additive may complicate health issues, but further research is needed. According to some medical studies, PVC plasticizers may cause chronic diseases such as scleroderma, cholangiocarcinoma, angiosarcoma, brain cancer, and acrosteolysis. 2004, a team of Swedish and Danish academics found that the phthalates DEHP and BBzP, commonly used in PVC, were associated with allergies in children. A team of Swedish and Danish academics in 2004 found that the phthalates DEHP and BBzP, which are commonly used in PVC, were strongly associated with allergies in children.
For unplasticized polyvinyl chloride (U-PVC), due to the absence of plasticizers, there is no DEHP seepage, but the process usually add stabilizers, most of them are lead salt stabilizers, lead is a kind of toxic substances, in the use of the process will be seeped out, endangering human health, and also can not be ignored. Currently there are non-lead salt stabilizers, but the high cost has not been popularized.