原文：
一、阀门基础
1．阀门基本参数为：公称压力PN 、 公称通经DN
2．阀门基本功能：截断接通介质，调节流量，改变流向
3．阀门连接的主要方式有：法兰、螺纹、焊接、对夹
4．阀门的压力——温度等级表示：不同材质、 不同工作温度下，{zd0}允许无冲击工作压力不同
5 a管法兰标准主要有两个体系：欧州体系和美州体系。
b两个体系的管法兰连接尺寸xx不同无法互配；以压力等级来区分最合适：欧州体系为PN0.25、0.6、1.0、1.6、2.5、4.0、6.3、10.0、16.0、25.0、32.0、40.0MPa;美州体系为PN1.0（CIass75）、2.0( CIass150）、5.0( CIass300）、11.0 (CIass600）、15.0( CIass900）、26.0( CIass1500）、42.0( CIass2500）MPa。
c管法兰类型主要有：整体(IF)、板式平焊(PL)、带颈平焊(SO)、带颈对焊(WN)、承插焊(SW)、螺丝(Th)、对焊环松套(PJ/SE)/(LF/SE)、平焊环松套(PJ/RJ)和法兰盖(BL)等。
d法兰密封面型式主要有：全平面(FF)、突面(RF)、凹(FM)凸(M)面、榫(T)槽(G)面、环连接面(RJ)等
二、常用（通用）阀门
1．一般工业用阀门型号编制方式，用七个单元来表示。其含义
类型 驱动方式 连接形式 结构形式 阀座密封面及衬里材料 公称 压力 阀体材料
2．阀门类型代号的Z、J、L、Q、D、G、X、H、A、Y、S分别表示：
闸阀、截止阀、节流阀、球阀、蝶阀、隔膜阀、旋塞阀、止回阀、安全阀、减压阀、疏水阀
3．阀门的连接式代号1、2、4、6、7分别表示：
1、内螺纹、2、外螺纹、4、法兰、6、焊接、7、对夹
4．阀门的传动方式代号9、6、3分别表示：
9、电动、6、气动、3、涡轮蜗杆
5．阀体材料代号Z、K、Q、T、C、P、R、V分别表示：
灰铸铁、可锻铸铁、球墨铸铁、铜及合金、碳钢、铬镍系不锈钢、铬镍钼系不锈钢、铬钼钒钢
6．阀座密封或衬里代号R、T、X、S、N、F、H、Y、J、M、W分别表示：
奥氏体不锈钢、铜合金、橡胶、塑料、尼龙塑料、氟塑料、Cr系不锈钢、硬质合金、衬胶、蒙乃尔合金、阀门本体材料
7．铸铁阀体不适合用于的场合有：
1）水蒸气或含水量多的湿气体；2）易燃易爆流体；
3）环境温度低于－20℃场合；4）压缩气体。
三、控制阀
1． 控制阀由 阀体 和 执行执行机构及其附件组成。
2．气动薄膜执行机构有 正作用 和 反作用 两种形式；随信号压力增大，推杆下移为正作用，反之推杆上移为反作用；通常接受标准信号压力为 20~100KPa ；带定位器时{zg}压力为 250KPa 。基本行程有六种（mm）：
10; 16; 25; 40; 60; 100 。
3．与气动执行机构相比电动执行机构有何特点，有哪几种输出形式？
驱动源为电力简单方便，推力、扭矩大，刚度大。但结构复杂，可靠性差。在中小规格上比气动的贵。常用于无气源或不需严格防爆、防燃的场合。
有角行程、直行程、和多回转三种输出形式。
4．直通单座调节阀有何特点？应用在何场合？
1)泄流量小，因只有一个阀芯易保证密封。标准泄流量为0.01%KV,进一步设计可作切断阀。
2)许用压差小，因不平衡力推力大。DN100的阀△P仅为120KPa。
3)流通能力小。DN100的KV仅为120。
应该应用于泄漏量小，压差不大的场合。
5．直通双座调节阀有何特点？应用在何场合？
1)许用压差大，因可抵消许多不平衡力。DN100的阀△P为280KPa。
2) 流通能力大。DN100的KV为160。
3) 泄漏量大，原因有两个阀芯不能同时密封。标准泄流量为0.1%KV,为单座阀10的倍。
主要应用于高压差，泄漏量要求不严的场合。
6．套筒调节阀有何主要优点？
兼有单、双座阀的优点。主要有：
1)稳定性好。因用阀塞节流代替阀芯阀座节流，而阀塞设有平衡孔可减少介质作用在阀塞上的不平衡力。同时套筒与阀塞间导向面大，加之不平衡力变化小，因此不易引起阀芯振动。
2)互换性和通用性强。只要更换套筒就可得到不同的流量系数和不同的流量特性。
3)允许压差大，热膨胀影响小。带平衡孔的套筒阀的平衡原理和双座阀一样，因此许用压差大。又由于套筒、阀塞采用同一种材料制成，温度变化引起的膨胀基本一致。
4)套筒提供的节流窗口有开大口和打小孔（喷射型）两种。后者有降噪、减振作用，进一步改进即成专门的低噪音阀。
适用于阀前后压差大，噪音要求低的场合。
7．除单、双座阀及套筒阀外还有哪些具有调节功能的阀？
隔膜阀、蝶阀、O型球阀（以切断为主）、V型球阀（调节比大、具剪切作用）、偏心旋转阀。
8．什么是调节阀的可调比R、理想可调比、实际可调比？
调节阀所能控制的{zd0}流量和最小流量之比称为可调比R.。
当阀两端压差保持恒定时，{zd0}流量与最小流量之比称为理想可调比。
实际使用中阀两端压差是变化的，这时的可调比称为实际可调比。
9．理想可调比取决于：阀芯结构
实际可调比取决于：阀芯结构、配管状况
国产直通单、双座调节阀的R值为：30精小型调节阀，高性能调节阀，V型球的R
10．什么是调节阀的流量系数C 、Cv 、KV值？
调节阀流通能力的大小用流量系数表示。
1)工程单位制Cv定义：调节阀全开时，阀前后压差为1kgf/cm2,温度5~40℃的水每小时所通过的立方米数。
磅/英寸2）温2)英制单位制C定义：调节阀全开时，阀前后压差为1bf/in2（1度60。F的水每分钟所通过的美加仑数。
3) 国际单位制KV：调节阀全开时，阀前后压差为100kPa,温度5~40℃的水每小时所通过的立方米数。
Cv =1.17 KV
KV=1.01 C
11．执行机构的输出力要满足调节阀所需的哪几部分力？
1)克服阀芯所受的静态不平衡力。
2)提供阀座负载的紧压力。
3)克服填料摩擦力。
4)特定应用或结构所需的附加力（如波纹管、软密封等）。
12．调节阀的流开、流闭指的是什么？
是对介质流动方向而言，与调节阀的作用方式气开、气闭无关。流向的重要性在于它影响到稳定性，泄漏和噪音等。
定义：在节流口，介质流动方向与阀门打开方向相同叫流开：反之，叫流闭。
13．哪些阀需进行流向选择？如何选择？
单密封类的调节阀如单座阀、高压阀、无平衡孔的单密封套筒阀需进行流向选择。
流开、流闭各有利弊。流开型的阀工作比较稳定，但自洁性能和密封性较差，寿命短；流闭型的阀寿命长，自洁性能和密封性好，但当阀杆直径小于阀芯直径时稳定性差。
单座阀、小流量阀、单密封套筒阀通常选流开，当冲刷厉害或有自洁要求时可选流闭。两位型快开特性调节阀选流闭型 。
14．选择执行机构应考虑哪三个主要因素？
1)执行机构的输出要大于调节阀的负荷，且合理匹配。
2)要检查标准组合时，调节阀所规定的允许压差是否满足工艺要求。大压差时要计算阀芯所受的不平衡力。
3)执行机构的响应速度是否满足工艺操作要求，尤其是电动执行机构。
15．确定调节阀口径的七个步骤是什么？
1)确定计算流量——Qmax 、Qmin
2)确定计算压差——根据系统特点选定阻力比S值，然后确定计算（阀全开时）压差；
3)计算流量系数——选择合适的计算公式图表或软件求KV的max和min ；
4) KV值选取——根据KV的max值在所选产品系列中最接近一档的KV，得到初选口径；
5)开度验算——要求Qmax 时≯90％阀开度；Qmin时≮10％阀开度；
6)实际可调比验算——一般要求应≮10；R实际＞R要求
7)口径确定——若不合格重选选KV值，再验证。
16．气动调节阀的辅助装置（附件）有哪些？各起什么作用？
1)阀门定位器——用于改善调节阀的工作特性，实现正确定位；
2)阀位（行程）开关——显示调节阀上、下限的行程工作位置；
3)气动保位阀——气源故障时保持阀门当时位置；
4)电磁阀——实现气路的自动切换。单气控用二位三，；双气控用二位五通；
5)手动机构——系统故障时可切换手动操作；
6)气动继动器——使气动薄膜执行机构动作加快，减少传递时间；
7)空气过滤减压器——气源净化、调压用；
8)贮气罐——气源故障时，使阀能继续工作一段时间，一般需三段保护时配。
17．什么情况下需要采用阀门定位器？
1)摩擦力大，需xx定位的场合。例如高温、低温调节阀或采用柔性石墨填料的调节阀；
2)缓慢过程需提高调节阀响应速度的场合。例如，温度、液位、分析等参数的调节系统。
3)需要提高执行机构输出力和切断力的场合。例如，DN≥25的单座阀，DN＞100的双座阀。阀两端压降△P＞1MPa或入口压力P1＞10MPa的场合。
4)分程调节系统和调节阀运行中有时需要改变气开、气关形式的场合。
5)需要改变调节阀流量特性的场合。
18．自力式调节阀有何特点？自力式压力调节阀型号中的K、B代表什么？
自力式调节阀又称直接作用调节阀。不需任何外加能源，并且把测量、调节、执行三种功能统一为一体，利用被调对象本身能量带动其动作的调节阀。它具有结构简单、价格便宜、动作可靠等特点。适用于流量变化小、调节精度要求不高或仪表气源供应困难的场合。
自力式调节阀按其用途可分为：压力、液位、温度和流量调节阀。目前生产最多的是压力调节阀和氮封阀。
K——压开型 ，泄压用，阀前稳定；
B——压闭型 ，稳压用，阀后稳定。
19．当阀选大了或需方工艺条件变化，使调节阀经常在小开度下工作，此时有何解决办法？
1)降低阀上压差△P
a在阀后加节流孔板消耗一部分压降；
b关小管路上串联的手动阀，至调节阀获得较理想工作开度为止；
2)缩小口径
a换小一档口径的阀；
b阀体不变，换小一档口径的阀芯、阀座。；
20．试述电动执行机构整体型与非整体型、调节型与开关型、电子式与智能型的含义。
1)整体型又称一体化，是将电气控制元件整体组合后装配在执行机构主机上。反之为非整体型，最早产品均为非整体型。整体型可减少控制室内的有关设施，还可相对减少控制电缆的芯数。非整体型常用于空间限制、高温环境、有振动影响的场合。
2)调节型：接收4~20mA. 1~5V模拟量控制信号通过电气控制元件使执行机构输出与控制信号成比例关系的角（直线）位移。
3)开关型：接收脉冲触点信号，执行机构输出轴只能控制在开和关的两个极限位置。也可输出脉冲触点信号。
4)电子式：将电气控制元件电子化、集成化。
5)智能型：在电子式的基础上，增加人机对话功能，电路从模拟电路升级到数字电路。特征之一配有外部设定器对执行器进行参数设置和调整。
21.为什么说将调节阀的气开、气关理解为就是正作用与反作用是错误的？
调节阀由执行机构和阀体部件两部份组成。调节阀一般采用气动薄膜执行机构，其作用方式有正作用和反作用两种。随信号压力增大，推杆下移为正作用，反之推杆上移为反作用；
阀体部件分为正装和反装两种。阀杆下移时与阀座间流通截面积减小的称为正装式，反之称为反装式。
调节阀的作用方式分为气开和气关两种，有信号压力时调节阀关，无信号压力时调节阀开为气关式，反之为气开式。气开、气关是由执行机构的正、反作用和阀体部件的正、反装组合而成，组合方式如下：
执行机构（作用） 阀体部件（装配） 调节阀（整机）
正 正 气关
正 反 气开
反 正 气开
反 反 气关
22填空
a被调介质流过阀门的相对流量（Q/Qmax）与阀门相对行程（l/L）之间的关系称为调节阀的流量特性。
b阀前后压差保持不变时，上述关系称为理想流量特性。
c实际使用中，阀前后压差总是变化的，此时上述关系称为工作流量特性。
d理想流量特性取决于阀芯形状。
e工作流量特性取决于阀芯形状和配管状况。
23.根据下述情况，选择调节阀的流量特性。
a调节阀经常在小开度下工作时，宜选用等百分比特性。
b二位调节应选用快开特性。
c当被调介质含有固体悬浮物时，宜选用直线特性。
d程序控制应选用快开特性。
e在非常稳定的调节系统中，可选用等百分比或直线特性。
24.一台气动薄膜调节阀，若阀杆在全行程的50%位置，则流过阀的流量是否也在{zd0}流量的50%处？
不一定，要以阀的结构特性而定。在阀两端压差恒定的情况下，如是快开阀，则流量大于50%；如是直线阀，则流量等于50%；如是对数阀（等百分比阀），则流量小于50%。
25.阀门的直线流量特性与等百分比流量特性各有何优缺点？
a同一开度下，直线特性流量大，压差改变快，故调节速度比等百分比特性快。
b从流量的相对变化上看，直线特性小开度变化大，大开度变化小，使得小开度时调节作用太快、太强，易产生超调，引起振荡；大开度时调节作用太慢、太弱，不够及时灵敏。
而等百分比特性正好弥补了这个缺点，它的流量相对变化是一个常数，小开度时流量小，流量的变化也小，调节平稳缓和；大开度时流量大，流量的变化也大，调节灵敏有效，因而其适应性比直线特性强。
C、由于等百分比特性大部分流量集中在后面，开度70%时，相对流量仅36%，90%时为71%,因此等百分比特性阀的容量不易充分利用，故经济性差。选阀时，有时会出现选等百分比特性比选直线特性口径要大一档的情况，特别是大口径、特殊材料的阀，选用时更应加以考虑。
26.调节阀选用
a调节前后压差较小，要求泄漏量小，一般可选用单座阀。
b调节低压差、大流量气体可选用蝶阀。
c调节强腐蚀性介质，可选用隔膜阀、衬氟单座阀。
d既要求调节，又要求切断时，可选用偏心旋转阀。其他有此功能的还有球阀、蝶阀、隔膜阀。
e噪音较大时，可选用套筒阀。
f控制高粘度、带纤维、细颗粒的介质可选用偏心旋转阀或V型球阀。
g特别适用于浆状物料的调节阀有球阀、隔膜阀、蝶阀等。
“ Valve Basics ”是由提供的阀门行业新闻，译文仅供参考。另外，中国隔膜阀网还提供相关产品搜索： 、 、 、 、 、 、 、 、 、 等。
译文：
1, valve base
1. Valve basic parameters: nominal pressure PN, nominal by DN
2. Valve basic functions: truncate connected media, adjust the flow, changing the flow of
3. The main ways of connecting the valve: flange, thread, welding, and folder
4. Valve pressure - temperature rating, said: different materials, different working temperatures, the maximum allowable working pressure without shocks of different
5 a standard pipe flange has two main systems: the state system of Europe and American system.
b 2 system pipe flange dimensions can not be completely different with each other; to pressure levels
to distinguish the best: European system for the PN0.25, 0.6,1.0,1.6,2.5,4.0,6.3,10.0,16.0,25.0,32.0 , 40.0MPa; U.S. state system as PN1.0 (CIass75), 2.0 (CIass150), 5.0 (CIass300), 11.0 (CIass600), 15.0 (CIass900), 26.0 (CIass1500), 42.0 (CIass2500) MPa.
c flange types are: general (IF), plate flat welding (PL), with neck flat welding (SO), with neck butt (WN), socket welding (SW), screw (Th), butt Central Loose (PJ / SE) / (LF / SE), flat weld loose sets (PJ / RJ) and the cover flange (BL) and so on.
d flange sealing surface types are: full flat (FF), suddenly face (RF), Au (FM) convex (M) face, tongue (T) slot (G) face, ring joint face (RJ), etc.
Second, common (generic) valve
1. General industrial valve model presentation, with seven units to represent. Its meaning
Type of driver seat structure connected in the form of the sealing surface and lining material body material Nominal pressure
2. Valve type code of Z, J, L, Q, D, G, X, H, A, Y, S respectively:
Gate valve, globe valve, throttle valve, ball valve, butterfly valve, diaphragm valve, plug valve, check valve, safety valve, reducing valve, steam trap
3. Valve connection type code 1,2,4,6,7 respectively:
1, internal thread, 2, male, 4, flange, 6, welding, 7, of the clip
4. The valve drive system, code-named 9,6,3 respectively:
9, electric, 6, Pneumatic, 3, Turbo Worm
5. Body Material Code Z, K, Q, T, C, P, R, V respectively:
Gray cast iron, malleable iron, ductile iron, copper and alloys, carbon steel, chromium nickel stainless steel, chrome-nickel molybdenum stainless steel, chrome molybdenum vanadium steel
6. Seating or lining code R, T, X, S, N, F, H, Y, J, M, W respectively:
Austenitic stainless steel, copper alloys, rubber, plastics, nylon plastic, fluorine plastic, Cr series
stainless steel, alloy, rubber lining, Monel alloy, valve body materials
7. Cast iron valve body is not suitable for the occasion are:
1) The number of wet steam or water content of gas; 2) flammable liquid;
3) The ambient temperature is below -20 ℃ occasions; 4) compressed gases.
3, control valve
1. Control valve body and the implementation by the implementing agency and its annexes.
2. Pneumatic membrane actuator action and reaction there are two forms; with the signal pressure, putting down a positive role, instead putting the shift is counter-productive; generally accepted standard signal pressure of 20 ~ 100KPa; with the highest when Locator pressures 250KPa. There are six basic stroke (mm):
10; 16; 25; 40; 60; 100.
3. Compared with pneumatic actuator electric actuator What are the characteristics, which of several output format?
Easy driving source for the power, thrust, torque, stiffness. However, complex structure, poor reliability. In the small and medium size expensive than air. Commonly used in non-gas source or without rigorous proof, flame occasions.
Angular travel, direct travel, and multi-turn form three types of output.
4. Through single-seat control valve What are the characteristics? Used in any situation?
1) The discharge capacity is small, because only one cartridge easy to ensure the seal. Standard vent flow 0.01% KV, further design can be used for shut-off valve.
2) the allowable pressure difference, pushing force due to a large imbalance. DN100 valve △ P only 120KPa.
3) The ability of small circulation. DN100 of only 120 KV.
Should be applied to leak a small amount
of pressure is not the occasion.
5. What are the characteristics through engine valve? Used in any situation?
1) The allowable pressure, died of a number of unbalanced force can be offset. DN100 valve △ P as 280KPa.
2) The flow capacity. DN100's KV 160.
3) The leak volume for two reasons spool can not both be sealed. Discharge standard for the 0.1% KV, single-seat valve 10 times.
Mainly used in pressure differential, leakage demands strict occasions.
6. What are the main advantages of the sleeve valve?
Both single and double seat valves advantages. Are:
1) stability. Throttle valve plug due to replace the valve with a throttle valve seat, the valve plug has a balance hole can reduce the media role in the unbalanced force in the valve stuck. Simultaneously with valve plug between the guide sleeve is large, coupled with unbalanced force change is small, so difficult to cause the valve vibration.
2) the interchangeability and versatility. As long as the replacement of the sleeve can be different flow coefficients and different flow characteristics.
3) to allow pressure large, small thermal expansion effect. Sleeve valve hole with a balance of equilibrium and two-seat valve, so too big allowable pressure. Also, because the sleeve, the valve plug using the same material, the temperature change caused by the expansion of the basic agreement.
4) sleeve to provide the cutting window has opened its mouth and playing with small holes (spray) two. The latter noise, vibration effects, and further improvement is needed for a special low-noise valve.
Apply pressure valve before and after the big occasions that require low noise.
7. In addition to single, double seat valve and sleeve valve which also has a regulatory function outside of the valve?
Diaphragm valve, butterfly valve, O
type ball valve (to cut off the main), V-type ball valve (to regulate than large, with shear), Eccentric rotary valve.
8. What is an adjustable valve than R, the ideal adjustable ratio, ratio of the actual adjustable?
Valve can control the maximum flow and minimum flow ratio as adjustable ratio R..
When the valve to maintain constant pressure at both ends, the maximum flow and minimum flow rate adjustable ratio as the ideal ratio.
Both ends of the actual use of the valve pressure is changing, when the adjustable variable than as the actual ratio.
9. Adjustable depending on the ideal ratio: spool structure
Than can actually be adjusted depending on: valve structure, piping condition
Made through a single, double seat control valve of the R value: a small regulating valve 30 fine, high-performance control valve, V-ball R
10. What is the valve flow coefficient C, Cv, KV value?
Flow control valve with a flow capacity of the size of the coefficient of that.
1) The definition of engineering units system Cv: valve fully open, the valve before and after the pressure was 1kgf/cm2, 5 ~ 40 ℃ temperature of the water passed by the number of cubic meters per hour.
Lb / inch 2) temperature 2) Imperial system of units C Definition: valve fully open, the valve before and after the pressure is 1bf/in2 (1 ° 60. F water per minute passed by the United States gallons.
3) The International System of Units KV: regulating valves fully open, the valve before and after the pressure was 100kPa, temperature 5 ~ 40 ℃ water adopted by the number of cubic meters per hour.
Cv = 1.17 KV
KV = 1.01 C
11. Implementing agencies to meet the output power control valve parts which needed to power?
1) to overcome the static unbalance force suffered spool.
2) Tight seat load pressure.
3) to overcome the friction packing.
4) required for a specific application or additional force structure (such as bellows, soft sealing, etc.).
12. The flow control valve opening, flow close refers to what?
Is the flow direction of medium, the mode of action with the gas valve to open, close air has nothing to do. Flow is important because it affects the stability, leakage and noise.
Definition: In the throttle, the medium flow direction and the direction of the same name to open the valve to open stream: On the contrary, called Stream closed.
13. What needs to flow valve selection? How to choose?
Single seal type valves, such as single-seat valves, high pressure valve, no balance hole needed for a single seal the sleeve valve flow selection.
Away and closed flow advantages and disadvantages. Open-type valve work flow is relatively stable, but less self-cleaning and sealing performance, short life; flow closed-type valve life long self-cleaning properties and good sealing, but when the valve stem diameter, the diameter is less than stable poor.
Single-seat valves, low flow valve, single-sleeve valve normally sealing the election away and, when washed powerful or have self-cleaning requirements optional flow closed. The two characteristics of fast closed-type flow control valve selection.
14. Select which of the implementing agencies should consider three main factors?
1) The executive body of the output is greater than the load control valve, and a reasonable matching.
2) To check the standard combination, the control valve is provided to allow pressure to meet the process requirements. Large pressure difference to calculate unbalanced force suffered spool.
3) The executive body of the response speed of operation to meet the process requirements, in particular the electric actuator.
15. Determine the control valve bore seven steps?
1) determine the calculation of flow - Qmax, Qmin
2) determine the calculation of pressure - according to the system characteristics of the selected resistance than the S value, and then determine the calculation of (valve fully open) pressure;
3) Calculate the flow coefficient - Select the appropriate chart or formula for calculating the max and software requirements KV min;
4) KV value selection - according to the max value of KV in the selected product line closest to a file KV, are primary aperture;
5) opening checking - when asked Qmax ≯ 90% valve opening; Qmin ≮ 10% when the valve opening;
6) The actual adjustable ratio check - General requirements should ≮ 10; R actual> R requirements
7) Diameter OK - failed re-election if the election KV value, and then verify.
16. Pneumatic control valve of the auxiliary equipment (accessories) What? What role each?
1) Valve Positioner - Valve used to improve the working characteristics, to achieve the correct positioning;
2) valve position (stroke) switch - Display control valve, the lower limit of travel work location;
3) to secure his position pneumatic valve - gas supply fails to keep the valve position at that time;
4) Solenoid Valve - automatically switches to achieve air routes. Single air control with two three; pneumatic control with two five-pass;
5) Manual institutions - failure to switch the system manually;
6) After pneumatic actuator - pneumatic membrane actuator moves to speed up and reduce the delivery time;
7) Air Filter Regulator - Gas Source, regulator with;
Eight) air tank - air supply fails, the valve will continue to work for a period of time, normally takes three sections protected with.
17. Under what conditions to use valve positioner?
1) friction large, need accurate positioning of the occasion. Such as high temperature, low temperature control valve or the use of flexible graphite filler valve;
2) The slow process may be improved valve response speed of occasions. For example, temperature, level, analysis and other parameters of the conditioning.
3) The need to improve the implementation of the output power and cutting force of the occasion. For example, DN ≥ 25 single-seat valve, DN> 100 of the seat valve. Pressure drop across valve △ P> 1MPa or inlet pressure P1> 10MPa occasions.
4,) Split-conditioning system and control valve operation is sometimes necessary to change the open air, gas related forms of occasions.
5) The need to change the control valve flow characteristics of the occasion.
18. Self-regulating valve What are the characteristics? Self-pressure regulating valve models in the K, B represent?
Self-regulating valve is also called a direct role in regulating valve. Without any external energy, and the measurement, regulation, implementation of the three functions unified into one, using the object itself is transferred energy to drive its action valve. It has a simple structure, cheap, reliable action and so on. Applicable to flow changes, the adjustment less precision or instrument air supplies difficult situation.
Self-regulating valve can be divided according to their purpose: pressure, level, temperature and flow control valve. Most current production is the pressure regulating valve and the nitrogen valve closure.
K - pressure open type, with pressure relief valve before the stable;
B - pressure closed, regulators use, the valve stability.
19. When the valve selected big changes in process conditions or the demand side, so that valves often working under the small opening, then any solution?
1) reducing valve on the pressure difference △ P
a throttling orifice in the valve consumes part of the added pressure drop;
b off road series of small tubes manual valve, control valve to get better job opening up;
2) reduce the diameter
a change of a file small-caliber valve;
b body unchanged for small-diameter spool a file, the valve seat. ;
20. Shishu actuators holistic and non-general type, adjustment type and switch type, electronic and intelligent meaning.
1) the overall type called integration, is the overall combination of electrical control components, after assembly in the implementing agencies on the host. On the contrary non-holistic, the first products are non-holistic. Type can reduce overall control room facilities, also reduced the number of control cable cores. Non-general type commonly used in space limited, high temperature environment, vibration occasions.
2) Regulation Type: Receive 4 ~ 20mA. 1 ~ 5V analog control signal through the electrical control components to enable the implementation of the output and control signal proportional to the angular (linear) displacement.
3) Switch: contact pulse signal received, the implementing agency can control the output shaft and off the two extreme positions. Contact signal can be output pulse.
4) electronic: electronic components to electrical control, integration.
5) Smart: In the electronic basis, increasing man-machine conversation function, the circuit to upgrade from analog to digital circuitry. One feature set with an external connector on the actuator to set and adjust parameters.
21. Why would the gas valve open, air to close interpreted as positive and negative effects is wrong?
Valve body parts by the implementing agencies and the two parts. General pneumatic membrane valve actuator, its mode of action there are two kinds of action and reaction. With the signal pressure, putting down a positive effect, putting the move to counter the contrary;
Body parts are divided into two kinds of suits and counter-mounted. Down with the valve seat stem cross-sectional area between the decrease in circulation as being mounted, otherwise known as anti-loading.
Mode of action of control valve to open gas off gas into two, with the signal pressure regulator valve off, no signal pressure to open the gas valve off type, whereas for the open air. Open air, air to close by the implementing agencies of the positive reaction and body parts is, a combination of anti-installed, combination in the following manner:
Implementing agencies (to be) body parts (assembly) valve (machine)
Precisely the relevant gas
Are anti-air open
Counter is open air
Anti-anti-air to close
22 Fill in the blank
a medium flow through the valve to be adjusted relative flow rate (Q / Qmax) and the relative valve travel (l / L) called the relationship between the control valve flow characteristics.
b valve before and after the pressure is constant, the relationship as the ideal flow characteristics.
c actual use, the valve before and after the pressure is always changing, this time as the relationship between work flow characteristics.
d depends on the disc shape of the ideal flow characteristics.
e work flow characteristics depend on the shape and distribution pipe spool condition.
23. According to the following cases, select the control valve flow characteristics.
a control valve in the small opening under the regular hours of work, such as the percentage of properties should be chosen.
b 2 features quick adjustment should be used.
c When adjusted medium containing suspended solids, the better to use the straight-line features.
d program control features should be used to open soon.
e-conditioning system in a very stable, you can use equal percentage or linear characteristic.
24. A pneumatic membrane valve, if the stem in 50% of full travel position, the flow through the valve the maximum flow of traffic is also 50% of office?
Not necessarily, structural characteristics of the valve should be. Both ends of the valve under constant pressure, so quick opening valve, the flow of more than 50%; the case of linear valve, the flow is equal to 50%; the case of the number of valves (such as percentage of the valve), then the flow is less than 50%.
25. Valve with equal percentage flow characteristics of linear flow characteristics of what advantages and disadvantages of each?
a same opening, the line features flow rate, pressure to change quickly, so adjust the percentage of features such as faster than the speed.
b From the relative changes in flow point of view, a small opening line features changes, large changes in opening small, the small opening when the regulation is too fast, too strong, easy to overshoot, causing oscillation; large opening when the regulation too slow, too weak, not enough time sensitive.
The equal percentage characteristics make up this shortcoming, its relative change is a constant flow, a small opening when the flow is small, changes in traffic also is small, smooth adjustment ease; large opening when the flow rate, flow rate changes are also great, regulation sensitive and effective, and therefore its adaptability stronger than the linear features.
C, the percentage of properties because the majority of such flows concentrated in the back, opening 70%, the relative flow of only 36%, 90%, 71%, the percentage of features such as easy fully utilize the capacity of the valve, so the economy is bad. Selection valve, and sometimes choose the percentage of features such as linear features than the selected aperture to freshman files, especially large diameter, a special material valve, when used should be considered.
26. Control valve selection
a small pressure difference before and after regulation to require a small amount of leakage, and can be used single-seat valve.
b low dropout regulator, high flow gas valve can be used.
c regulate strong corrosion, may choose diaphragm, fluorine single-seat valve.
d not only want to regulate, but also called for cutting off may make use of eccentric rotary valve. There are other features of this valve, butterfly valve, diaphragm valve.
e noisy, they can use the sleeve valve.
f control high viscosity, with fibers, fine particles of the medium can be used or eccentric rotary valve V-ball valve.
g particularly suitable for slurry materials are ball valves, diaphragm valves, butterfly valves and so on.
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