The anti-corrosion solenoid valve of Australia and Macao includes: ABS solenoid valve, PVC solenoid valve, PP solenoid valve, UPVC solenoid valve, CPVC solenoid valve, PTFE solenoid valve, PVDF solenoid valve. Attachment: Fluid solenoid valve selection and installation characteristics 1. Safety:
Anti-corrosion solenoid valve is not a universal solenoid valve.
From an economic point of view, there is no need to use anti-corrosion solenoid valves for non-corrosive media. Nowadays, the general fluid solenoid valve technology is very mature, and there are many manufacturers. It can be said that the water solenoid valve can be used as long as it is affordable.
From a safety point of view, it is best not to use an anti-corrosion solenoid valve for high pressure (more than 10 Bar). Because the material used for anti-corrosion solenoid valve is mostly made of plastic material, its anti-corrosion performance is only for medium that metal can not bear, such as hydrochloric acid. Even dilute sulfuric acid, even stainless steel 316, cannot be used. It is well known that plastic withstand voltage is limited.
From the point of view of applicability, the medium with too much impurity should be carefully used with anti-corrosion solenoid valve. The impurities of hard particles are easy to cause irreparable wear on the plastic, resulting in leakage and leakage. In addition, impurities may be squeezed between the valve core and the valve cavity. The solenoid valve fails to work, unless the filter is installed in front of the valve, do not use it as well!
In particular, many manufacturers like to exaggerate their products. For example, they all claim that PTFE solenoid valves, plastic king solenoid valves, can be used in almost all medium fluids, but they are practically impossible. They often ignore solenoid valves. The performance of the sealing material, even if it is a perfluororubber, has limitations in use. The solenoid valve with PTFE sealing solves the problem of corrosion, but the plastic deformation of the material is easy to cause the manufacturing process to be difficult. Improve, the actual application does not mean much.
There are thousands of chemicals in the world, no one can understand the performance of all chemicals, so the selection of anti-corrosion solenoid valves mainly used for chemicals is very important. For known substances, you can rely on the former. People's experience to judge, for the unknown substances, we can only know from the actual use, 15 years ago, the Australian market is positioned in anti-corrosion valves, painstakingly developed for many years, a large number of practical use cases, experience - let us calmly face different Customer consultation. Our confidence comes from the affirmation of customers for more than 10 years.
1. Corrosive media must use anti-corrosion solenoid valve, generally made of plastic (including ABS, PVC, PP, PTFE, PVDF). Some can also choose all stainless steel, such as organic solvent (remember to be all stainless steel, organic solvent will corrode rubber) .
2, the explosive environment must use the corresponding explosion-proof grade products, open-air installation should take into account the waterproof and anti-UV radiation aging, dust should be considered in dusty occasions. Referred to as the explosion-proof solenoid valve, waterproof solenoid valve, dust-proof solenoid valve.
3. The nominal pressure of the solenoid valve should be greater than the maximum working pressure of the medium in the pipeline.
Second, applicability:
1, gas, liquid or gas-liquid mixed state should use different types of solenoid valves, targeted choices will never be wrong.
2, the medium temperature is different, choose different materials, and should be selected within the allowable range of the solenoid valve, otherwise the valve body is easy to damage, the coil is easy to burn, the seal is aging deformation, seriously affecting the service life of the solenoid valve.
3. The viscosity of the medium is usually below 50 cSt. If you exceed this value, you usually need to order it.
4, the medium cleanliness is not high, when there are more impurities, the filter should be installed in front of the solenoid valve. Easy plugging card is a common problem of solenoid valves.
5, the medium is generally not allowed to reverse flow should be one-way circulation, if there is a back pressure difference should be installed check valve. If two-way circulation is required, it is best to use other suitable control valves.
6. The minimum working pressure difference is above 0.04Mpa, which is optional indirect pilot type; the minimum working pressure difference is close to or less than zero, you must use direct-acting or step-by-step direct type.
7. According to the type of power supply, the voltage specification should be as high as AC220V and DC24V, which is convenient to use.
8. The fluctuation of the power supply voltage is generally allowed to be ±%10. If there is too much difference, the voltage regulation measures must be taken. This is only the standard of the domestic coil, and the requirements for the imported coil may be higher.
9. The rated current and power consumption should be selected according to the power supply capacity. It should be noted that the VA value is higher when the AC starts, and the low-power solenoid valve should be preferred when the power supply capacity is insufficient.
10. Solenoid valves are generally only open and closed. They should be carefully considered when the control accuracy is high and the flow needs to be adjusted.
11. The operating time of the solenoid valve is generally faster, a few milliseconds faster, and less than one second slow. It should be considered whether a water hammer is generated in the pipeline.
12. The amount of leakage is O is the dream of most manufacturers, but there are always unsatisfactory practical applications, so it is necessary to fully consider whether this will have a serious impact on production.
Third, reliability:
1. Regarding the service life, the service life is different under different working conditions. The solenoid valve, which is said to be used millions of times, may not be used in a harsh environment, so the full user and producer are selected. Communication is indispensable. Regular manufacturers generally have a one-year warranty period. If there is trouble during the warranty period, look for manufacturers.
2. Solenoid valves can generally be energized for a long time. Normally closed solenoid valves are used more. For long-time open and short-time shutdown, it is best to use normally open solenoid valves. If in some special protective situations, that is, when the power must be turned off, the normally closed type must be used.
3. When the operating frequency is relatively high, the direct-acting solenoid valve should be considered first, and the quick-acting type should be used when the diameter is relatively large.
Fourth, economic:
Many users will consider the cost, and the benefits are the last choice on the basis of meeting safety, application and reliability.
Five, installation notes:
1. The solenoid valve should not be installed in places where there is direct dripping or splashing water, otherwise the solenoid valve coil may burn or easily corrode the valve surface.
2. The solenoid valve should ensure normal operation within the fluctuation range of ±10% of the rated voltage.
3. When installing, please pay attention to the arrow on the valve body should be consistent with the flow direction of the medium. There should be no reverse pressure difference in the pipe installed by the solenoid valve, otherwise the check valve should be installed.
4, the solenoid valve should be thoroughly cleaned before installation, the medium should be free of impurities, the filter is installed in front of the valve.
5. In order to ensure the normal and continuous operation of the pipeline system, a bypass device should be installed to prevent the loss of the solenoid valve when it fails or needs to be cleaned.
6, the solenoid valve is best to install horizontal piping, such as the need for vertical piping installation should be a special requirement, manufacturers can generally order.
7. After the installation is completed, the test machine should be powered on several times. After the operation is normal, it can be put into use.
VI. Trouble and Troubleshooting 1. Do not work after the solenoid valve is energized Check if the power supply wiring is bad. → Reconnect the wiring and the connection of the connector. Check if the power supply voltage is in the working range. -→ Adjust the normal position range. Whether the coil is off-welded → Re-weld the coil short-circuit → Whether the pressure difference of the replacement coil is not suitable → adjust the pressure difference or replace the suitable solenoid valve fluid temperature is too high → replace the appropriate solenoid valve with impurities to make the main valve core and moving iron core of the solenoid valve jam → clean, if there is a seal Damage should be replaced and the filter installed liquid viscosity is too large → Replace the appropriate solenoid valve frequency is too high and the life has expired → Replace the solenoid valve 2, the solenoid valve can not close the main valve core or the moving iron core seal is damaged → Replace the seal Whether the temperature and viscosity of the fluid are too high → the solenoid valve of the replacement port has impurities entering the solenoid valve to produce the valve core or the moving iron core → the life of the cleaning spring has been reached or deformed → the orifice of the orifice is replaced and the cleaning frequency is too high. Or the life is up to → re-elect or renew the product 3, leak in other cases → check Check the seal for damage and the spring is not properly assembled. External leakage → loose connection or seal is broken. → tighten the screw or replace the seal. There is noise when energized → the loose parts are loose and tightened. Voltage fluctuations are not within the allowable range and the voltage is adjusted to the normal range. The iron core suction surface is dirty or uneven, and it is cleaned or replaced in time.
VII. Use and characteristics of fluid solenoid valve The fluid solenoid valve is used for the switching control of liquid and gas pipelines. It is a two-position control and can only be used as a switch. Generally used in small pipeline systems, common in DN50 and below pipelines. When the pipeline is relatively large, other types of valves are often selected, such as electric or pneumatic valves, but it can be automatically turned on and off when power is turned off and automatically turned off when power is lost. The valve is unmatched.
The solenoid valve generates a magnetic force as a driving force when the coil is energized. It can only be turned on or off. Changing the placement mode of the return spring can be divided into a normally closed or normally open type, and the power is turned on to be normally closed, and the power loss is turned on. Normally open.
Solenoid valves generally have a small flow coefficient, and the working pressure difference is not large, and the switching action time is very short. For example, the general solenoid valve circulation coefficient is much smaller than the ball valve and butterfly valve of the same specification. Some manufacturers claim to be able to achieve a solenoid valve with a pressure of several hundred Bar, but in reality there is no practical significance. Imagine that the pressure is so high. How much damage the pipe caused by closing the water hammer during the time.
Eight, commonly used sealing materials for solenoid valves 1. NBR nitrile rubber (nitrile butadiene rubber)
Made of butadiene and acrylonitrile by emulsion polymerization, the nitrile rubber is mainly produced by low-temperature emulsion polymerization, which has excellent oil resistance, high wear resistance, good heat resistance and strong adhesion. The disadvantages are poor low temperature resistance, poor ozone resistance, poor electrical properties, and slightly lower elasticity.
In addition, it has good water resistance, air tightness and excellent bonding properties. Widely used in various oil-resistant rubber products, a variety of oil-resistant gaskets, gaskets, casings, flexible packaging, soft rubber hoses, printing and dyeing rubber rollers, cable rubber materials, etc., in the automotive, aviation, petroleum, copying and other industries become essential Elastic material.
Nitrile rubber has excellent oil resistance, its oil resistance is second only to polysulfide rubber and fluororubber, and it has wear resistance and air tightness. The disadvantage of Dingqing Rubber is that it is not resistant to ozone and aromatic, halogenated hydrocarbons, ketones and ester solvents. It is not suitable for insulating materials.
The main purpose of nitrile rubber is mainly used in the production of oil-resistant products, such as oil-resistant pipes, tapes, rubber diaphragms and large oil bladders, etc., commonly used in the production of various types of oil-resistant molded products, such as O-rings, oil seals, cups, diaphragms, valves, Corrugated pipes, etc., are also used to make rubber sheets and wear parts.
2, EPDM EPDM (Ethylene-Propylene-Diene Monomer)
EPDM rubber is a terpolymer of ethylene, propylene and non-conjugated diene. The most important characteristic of EPDM is its superior resistance to oxidation, ozone and erosion. Since EPDM is a polyolefin family, it has excellent vulcanization characteristics. Among all rubbers, EPDM has the lowest specific gravity. It absorbs a large amount of fillers and oils and has little effect on properties. Therefore, it is possible to produce a rubber compound which is inexpensive.
Molecular Structure and Properties EPDM is a terpolymer of ethylene, propylene and a non-conjugated diene. Diolefins have a special structure, only one of the two bonds can be copolymerized, and the unsaturated double bonds are mainly used as a crosslink. The other unsaturated will not become the polymer backbone, it will only become the side chain. The main polymer chain of EPDM is fully saturated. This property makes EPDM resistant to heat, light, oxygen, and especially ozone. EPDM is essentially non-polar, resistant to polar solutions and chemicals, low in water absorption, and has good insulating properties.
Features:
Low density and high filling; aging resistance; corrosion resistance; water vapor resistance; superheat resistant performance; electrical properties; elasticity;
3, VITON fluorine rubber (FKM)
The fluorine-containing rubber in the molecule has various types depending on the fluorine content, that is, the monomer structure. Currently, the hexafluoride-based fluorocarbon rubber is first marketed by DuPont under the trade name "VITON", and the high temperature resistance is superior to most of the products. Rubber; chemical resistance, most oils and solvents (except ketones and esters), good weather resistance and ozone resistance, but poor cold resistance; generally used in seals of steam locomotives and chemical plants, temperature of use The range is -20 ° C ~ 260 ° C, low temperature requirements for low temperature type can be applied to -40 ° C.
4, NR natural rubber seals have good wear resistance, elasticity, tear strength and elongation. However, it is easy to age in the air, becomes sticky when exposed to heat, easily swells and dissolves in mineral oil or gasoline, and is alkali-resistant but not resistant to strong acid. It is suitable for use in liquids such as automobile brake oil and ethanol with hydroxide ions. The general temperature range is -20~100 °C.
5, FFKM perfluoro rubber Very good chemical resistance, acid, alkali, ketones, esters, ethers, strong oxidants and other chemicals. The highest heat resistance can reach 320 °C. It is usually used for the final polarity to solve the sealing problem. The price is nearly one hundred times that of the general rubber material, which is very expensive.
6, PTFE PTFE: excellent chemical resistance and heat resistance, can be applied in almost all occasions, air, light, ozone, temperature range -200 ° C ~ +250 ° C friction is small, no adhesion.
Nine, anti-corrosion solenoid valve body material 1, PVC
PVC (PolyVinylChloride Polyvinyl Chloride) generally has 7 grades (SG1-SG7) according to the hardness and properties of the material, and the density is about 1.4 g/cm^3. Below SG4 is generally a soft product. It needs to add a large amount of plasticizer during molding, mainly used for making artificial leather, wire and cable insulation, seals, etc. SG5 or above is a hard product, mainly used for making various pipes, such as drainage, electrician, postal tube and pipe fittings, various plates, sheets, profiles, etc. PVC molding shrinkage rate of 0.6-1.5%, has good mechanical properties, excellent electrical properties, self-extinguishing, strong acid and alkali resistance, good chemical stability, low price, is a very widely used Universal plastic. However, due to its low temperature, the highest temperature is around 80 °C, which hinders its development.
2, CPVC
CPVC resin is made of chlorinated modified polyvinyl chloride (PVC) resin and is a new type of engineering plastic. The product is white or light yellow odorless, odorless, non-toxic loose granules or powder. When the PVC resin is chlorinated, the molecular bond irregularity increases, the polarity increases, the solubility of the resin increases, and the chemical stability increases, thereby improving the heat resistance, acid resistance, alkali, salt, oxidant, etc. of the material. Corrosion. Increased numerical mechanical properties of heat distortion temperature, chlorine content increased from 56.7% to 63-69%, Vicat softening temperature from 72-82 °C, (up to 90-125 °C), maximum temperature up to 110 °C, The long-term use temperature is 95 °C. Among them, CORZAN CPVC performance indicators are better. Therefore, CPVC is a new type of engineering plastics with broad application prospects.
3, UPVC
U original text is "unplasticized", and PVC raw materials in which PVC raw materials are not added with "plasticizer". Without adding a "plasticizer", chlorine (Cl) in the PVC raw material will be completely volatilized, and the PVC raw material to which the "plasticizer" is added may have a large amount of residual chlorine (Cl) which cannot be volatilized. UPVC has no residual chlorine release. PVC will have residual chlorine released.
4, PP
PP is a semi-crystalline material. It is harder and has a higher melting point than PE. Since the PP temperature of the homopolymer type is very brittle when it is higher than 0 ° C, many commercial PP materials are random copolymers of 1 to 4% ethylene or a clamp copolymer of a higher ratio of ethylene. The copolymer type PP material has a low heat distortion temperature (100 ° C), low transparency, low gloss, low rigidity, but has a stronger impact strength. The strength of PP increases as the ethylene content increases. The Vicat softening temperature of PP is 150 °C. Due to the high degree of crystallinity, this material has excellent surface stiffness and scratch resistance. There is no environmental stress cracking problem in PP. Typically, PP is modified by the addition of glass fibers, metal additives or thermoplastic rubber. The flow rate of PP has a MFR ranging from 1 to 40. Low MFR PP materials have better impact resistance but lower elongation. For materials of the same MFR, the strength of the copolymer type is higher than that of the homopolymer type. Due to crystallization, the shrinkage rate of PP is quite high, generally 1.8 to 2.5%. And the direction uniformity of shrinkage is much better than materials such as PE-HD. The addition of 30% glass additive can reduce the shrinkage to 0.7%. Both the homopolymer type and the copolymer type PP materials have excellent moisture absorption resistance, acid and alkali corrosion resistance, and solubility resistance. However, it is not resistant to aromatic hydrocarbons such as benzene solvents, chlorinated hydrocarbons (carbon tetrachloride) solvents, and the like. PP does not have oxidation resistance at high temperatures like PE.
Polypropylene (PP) is one of the lighter plastics, and it has excellent electrical properties and can be used as a moisture-resistant high-frequency insulation material. PP is a crystalline polymer which exhibits a large shrinkage (1.0%-1.5%) due to a large change in specific volume and a high degree of molecular orientation during melt condensation. In the molten state of PP, the effect of lowering the viscosity by heating is not significant. Therefore, in the molding process, the injection pressure and shear rate should be increased to improve the molding quality of the product.
5, PVDF
The appearance of PVDF polyvinylidene fluoride is translucent or white powder or granules. The molecular chains are closely arranged and have strong hydrogen bonds. The oxygen index is 46%, non-combustible, crystallinity is 65%~78%, and density is 1.17. ~1.79g/cm3 melting point is 172 °C heat distortion temperature 112~145 °C long-term use temperature is -40~150 °C.
PVDF resin king refers to a vinylidene fluoride homopolymer or a copolymer of vinylidene fluoride and other small amount of fluorine-containing vinyl monomer. PVDF resin has the characteristics of fluororesin and general-purpose resin, in addition to good chemical resistance and resistance. In addition to high temperature, oxidation resistance, weather resistance, and radiation resistance, it also has special properties such as piezoelectricity, dielectric properties, and thermoelectric properties. It is currently the second largest product in the production of fluoroplastics. The production capacity exceeds 43,000 tons. PVDF applications are mainly concentrated in the three major fields of petrochemical, electrical and electronic and fluorocarbon coatings. Due to the good chemical resistance, processability and fatigue resistance and creep resistance of PVDF, it is the pump or valve of the petrochemical equipment fluid processing system as a whole or lining. One of the best materials for pipes, piping fittings, storage tanks and heat exchangers. Its good chemical stability and electrical insulation properties enable the equipment to meet TOCS and flame retardant requirements. It is widely used in the storage and transportation of high-purity chemicals in the semiconductor industry. In recent years, porous membranes made of PVDF resin have been used. Gels, separators, etc., are used in lithium secondary batteries, and this use is currently one of the fastest growing PVDF markets. PVDF is one of the most important raw materials for fluorocarbon coatings. The fluorocarbon coating prepared from it has been developed to the sixth generation. Because PVDF resin has excellent weather resistance, it can be used outdoors for a long time without maintenance. Widely used in power stations, airports, highways, high-rise buildings, etc. In addition, PVDF resin can also be blended and modified with other resins, such as PVDF and ABS resin to obtain composite materials, which have been widely used in construction, automobile decoration, and home appliance casings.