Note of control valve type selecting

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Summary of note of control valve type selecting: The item that need of place of correct type selecting notices control valve of this analysis of summary of section lecture key, press control valve a powerful person model, the experience that respect of nine of limits of way of character of actuator, material, discharge, effect, bedspring, flow direction, filling, accessory summed up control valve type selecting and note, understand the type selecting knowledge of control valve from personnel of course of study to control valve, raise type selecting level to have bigger help effect, but level of author of be confined to is finite, hard to avoid has a lot of inadequacy and problem, welcome wide readership to criticize point out mistakes so that they can be corrected. Knowledge of more valve type selecting clicks please enter: Special subject of valve type selecting. A powerful person choice: (1) decides nominal pressure, not be to use Pmax to cover PN, pledge by temperature, pressure, material 3 conditions find out corresponding PN to be satisfied at what picking the PN cost of a powerful person from inside the watch however. (The valve with certain 2) , its leakage rate satisfies craft requirement. (The valve with certain 3) , its job presses difference to should be less than the permission of a powerful person to press difference, if be no good, must consider from special angle or pick its a powerful person additionally. (The temperature of 4) medium is inside the working temperature limits of a powerful person, environmental temperature accords with a requirement. (5) prevents a problem according to what the sordid circumstance of medium considers a powerful person. (What 6) considers a powerful person according to the chemical function of medium is anti-corrosive problem. (7) is differred according to pressing and contain good thing medium, those who consider a powerful person is erosive reach wear-resisting damage issue. (The performance that 8) economic integration effect considers, price is compared. Need to consider 3 issues: A. The structure is simple (simpler reliability is higher) , safeguard convenient, spare parts to have source; B. Service life; C. The price. (9) actor chooses order. Butterfly a powerful person - odd an a powerful person - two-seater a powerful person - sleeve a powerful person - horny entity a powerful person - 3 a powerful person - ball valve - prejudicial rotary valve coming back - diaphragm valve. The choice of actuator: (1) is the simplest is pneumatic film mood, it is piston next, finally is electric. (2) is dynamoelectric actuator is main the advantage is drive source (power source) convenient, but the price is high, dependability, waterproof explosion proof is inferior to pneumatic actuator, answer so preferential choose pneumatic. (3) is old dynamoelectric actuator is cumbersome, we already had electronic type essence of life the dynamoelectric actuator of small-sized high reliability is offerred (the price is relevant tall) . (Filmy actuator of the ZMA with old 4) , ZMB can fall into disuse, by much bedspring light-duty actuator takes the place of (function rises, weight, height drops) of about 30 ％ . (Norms of breed of 5) piston actuator is more, old, suggest stupidly to be chosen no longer again greatly again, and choose light new structure. The choice of material: (Grade of compression of body of 1) a powerful person, use temperature and corrosion resistance can wait for a respect to answer not to provide the requirement of the path under craft join, answer preferential choose a manufactory to finalize the design product. (2) water vapour or hydrous more wet gas and combustible explode easily medium, unfavorable choose cast-iron a powerful person. (3) environment temperature under - when 20 ℃ (especially northward) , unfavorable choose cast-iron a powerful person. (4) is right cavitation, erosive in relatively serious medium temperature and the rectangular coordinates that press difference to form, its temperature is 300 ℃ , press difference for 1. When 5MPa connected the section beyond the line at 2 o'clock, to reduce expenditure sealing surface should choose wear-resisting material, if cobalt radical alloy or exterior v department are special Lai alloy. (5) is right strong caustic medium, choose be able to bear or endure what corrode alloy needs fibrous root occupies the sort of medium, chroma, temperature, pressure is different, the choice is right anti-corrosive material. (Body of 6) a powerful person and reduce expenditure treat respectively, rate of reduce expenditure of wall of body of a powerful person is minor and the corroding with certain be patient of, its are corroded rate is OK in Lmm ／ or so years; Reduce expenditure be eroded by high speed, corrode meeting bend [remove leak to increase, its are corroded rate should be less than 0.

1mm ／ year. (7) is right liner material (balata, plastic) the scope of application that the temperature of this job medium when the choice, pressure, chroma must satisfy this material, the physics, mechanical to it destruction when considering motion of a powerful person (be like shear failure) . (8) vacuum a powerful person is unfavorable choose balata of liner of body of a powerful person, plastic structure. (Two of system of 9) water treatment cut off a powerful person to should not be choose line balata material. (The model of 10) typical medium is able to bear or endure choice of corrode alloy material: A. Vitriolic: 316L, breath out family name alloy, 20 alloy. B. Nitric acid: Aluminous, c4 steel, c6 steel. C. Hydrochloric acid: Breath out family name B. D. Hydrofluoric acid: Meng Naier. E. Acetic acid, formic acid: Alloy of 316L, haing family name. F. Phosphoric acid: Because of but alloy of nickel Er, haing family name. G. Urea: 316L. H. Caustic soda: Meng Naier. I. Chlorine: Breath out family name C. J.

Seawater: Because of but nickel Er, 316L. (11) so far, the most all-purpose anti-corrosive material is 4 fluorine, call " be able to bear or endure corrode king " . Accordingly, should choose above all complete 4 fluorine are anti-corrosive a powerful person () of product of patent of Hua Lin place, below have to circumstance (be like temperature > 180 ℃ , PN ＞ 1. 6) just chooses alloy. The choice of discharge character: What offer below is abecedarian choice, detailed choice sees technical data: (1)S ＞ 0.

6 when choose logarithm character. (Logarithm character is chosen when change of 2) is small degree of job, unbalance is big. (3) asks be mirrorred by tone parameter choose when rate is rapid linear, slow when choose logarithm. (4) pressure regulating system is optional and straight characteristic. (5) fluid regulating system is optional and straight characteristic. Effect way chooses: (Leave below 1) abroad commonly used breakdown or close will express, namely breakdown leaves, breakdown closes, leave with the gas of our country, gas-tight state as it happens is contrary, breakdown opens correspondence gas-tight a powerful person, breakdown closes corresponding gas to drive a powerful person. (Small-sized a powerful person already did not stress the light-duty a powerful person or family with new 2) , choice of executive machinery action, counteractive, must note in end consequently on indicate. B(is gas-tight) K(enrages) the choice of bedspring limits: (1) is choice bedspring limits above all, define working bedspring scope even. (2) decides working bedspring limits involves computation to output force to overcome unbalance. If have difficulty, should the condition (basically be a powerful person when shutting press difference) tell a manufactory, assistance is calculated and mix up bedspring and working limits leave factory (at present, many manufacturer do computational) far from. The choice of flow direction: (1) is in reduce expenditure mouth, medium opens direction to flow to leave to flow to core of a powerful person, to close direction to flow to be shut to flow. (The choice that 2) flows to basically is odd sealed kind of control valve, have sheet a powerful person kind, horny a powerful person or family kind, a powerful person of odd sealed sleeve 3 kinds big. Base it is flowed to for the regulation (like ball of two-seater a powerful person, V) flow with random (like O ball) . (3) is become Dg ＞ 15 when, choose normally flow, when Dg ≤ the small-bore a powerful person of 15, especially high-pressured a powerful person is optional stream shut, in order to improve life. (4) is optional to two-gang switch a powerful person stream shut. (If 5) flows shut model a powerful person produces vibration, mend one's ways come, flow model can eliminate. The choice of filling: (1) control valve is commonly used is 4 fluorine " V " form filling and black lead " O " form filling. (4 fluorine of 2) filling attrition is small, but be able to bear or endure difference in temperature, life is brief; Attrition of black lead filling is big, but be able to bear or endure lukewarm good, life is long; A powerful person that high temperature falls and takes positioner suggests to choose black lead filling. (3) is like 4 fluorine filling to often be changed, can consider to use black lead filling. The choice of accessory: (The accessory of 1) control valve basically has: Positioner, converter, afterwards is moved implement, pressure boost a powerful person, protect an a powerful person, pressure-relief valve, filter, oily mist implement, journey switch, position sends message implement, electromagnetism a powerful person, handwheel. (2) accessory has compensatory function and the effect that make sure a powerful person moves. Increase necessarily, do not increase needlessly. Needless when increase accessory to meet huff reduces reliability. (The main function of 3) positioner is to raise output force and behavioral rate, when needing these functions, can not take, either it is good to took positioner. (4) is right answer a system quickly, not action of a powerful person is quick, optional converter. (The explosion proof circumstance with strict 5) , optional: Electric converter ＋ pneumatic positioner. (6) electromagnetism a powerful person should select reliable product, when preventing to want its action not movement. (7) fundamental situation suggests need not handwheel, prevent factitious misoperation. (8) had better be offerred by manufacturer home and assembly offers up a sacrifice in a powerful person goods, in order to assure the dependability of system and assembly connection. (When 9) orders goods, signal of the name that should provide accessory, model, norms, input, output signal. (10) re-iterate: Notice these please " dot " importance, especially dependability, if when necessary, hua Lin place but component of pneumatic of Japan of form a complete set, be like electromagnetism a powerful person. CNC Milling CNC Machining