机械密封选型指南

机械密封选型要求
机械密封是工业生产中非常重要的一种密封方式，它广泛应用于各种机械设备中，如离心泵、鼓风机、压缩机等。

选型合适的机械密封能够有效地防止泄漏，提高设备的稳定性和使用寿命。

机械密封选型的要求主要包括以下几个方面：
1. 适当的密封材料：机械密封的密封材料应该是具有较高耐磨性、耐腐蚀性和耐高温性的材料。

常用的密封材料有碳化硅、氧化铝、聚四氟乙烯等。

2. 正确的密封结构：机械密封的结构应该符合设备的要求，能够有效地避免泄漏。

常用的机械密封结构有单端面机械密封、双端面机械密封等。

3. 合适的密封参数：机械密封的密封参数包括压力、温度、转速等。

在选型时需要根据实际工作条件来确定合适的密封参数。

4. 可靠的密封性能：机械密封应该具有稳定可靠的密封性能，能够长期运行而不泄漏。

5. 方便的维护保养：机械密封应该具有方便的维护保养性能，能够方便地更换密封件，延长使用寿命。

总之，机械密封的选型要求是综合考虑密封材料、密封结构、密封参数、密封性能以及维护保养等方面的因素，确保选用的机械密封能够满足实际工作条件的要求。

- 1 -。

集装式机械密封选型流程集装式机械密封是机械设备中重要的一环，它能够在保证轴与壳体之间无泄漏的同时，避免由于轴与壳体之间的摩擦而产生的磨损。

在选择集装式机械密封时，需要经过以下几个流程：1.确定密封的应用环境首先需要确定密封的应用环境，是高温、高压、还是低温和低压。

不同的应用环境对密封材料的要求也是不同的，因此在选择密封时需要提前了解清楚，以免出现选型错误。

2.了解密封的工作原理在了解密封的工作原理之后，需要进一步了解密封的特性，例如它的密封性能、耐磨性、耐腐蚀性等。

这些特性能够保证密封在长期使用中不会出现问题，并且能够满足设备的工作要求。

3.考虑密封的材质密封的材质直接关系到密封的性能和寿命，因此需要根据实际需求选择合适的材质。

例如，对于高温、高压环境，需要选择高温密封材料，而对于低温和低压环境，则可以选择低温密封材料。

4.考虑密封的尺寸和结构密封的尺寸和结构也是影响其使用寿命和性能的重要因素，因此在选择时需要根据设备的具体要求选择合适的尺寸和结构。

5.考虑密封的安装方式密封的安装方式对密封的性能和寿命也有很大的影响，因此需要根据实际需求选择合适的安装方式。

例如，对于需要进行现场安装的设备，需要选择易于安装和拆卸的密封；而对于需要在设备运行过程中进行维护的设备，需要选择具有良好密封性能和可靠性的密封。

6.参考密封的性能数据在综合考虑以上因素后，还需要参考密封的性能数据，例如密封的耐压、耐温、耐腐蚀等指标，以确保密封的性能满足实际需求。

总之，在选择集装式机械密封时，需要综合考虑以上因素，尽量选择满足应用环境、工作原理和性能要求的密封。

只有这样，才能够保证密封的性能和寿命，为设备的安全运行提供保障。

机械密封选型要求
机械密封是一种常用的密封方式，适用于各种化工设备、泵、压缩机等机械设备的密封。

为了保证机械密封的正常工作，需要进行科学合理的选型。

机械密封选型要求如下：
一、工作环境
机械密封的选型需要充分考虑其工作环境，包括介质、温度、压力、转速等因素。

不
同的介质会对机械密封的材料和结构产生不同的影响，如高温、高压、腐蚀介质需要相应
的密封材料和结构。

同时，机械密封还要考虑机械设备的转速，以及机械密封的耐磨性、
耐热性、耐腐蚀性等性能。

二、密封形式
机械密封有多种形式，常见的有单端面机械密封、双端面机械密封、金属波动密封等。

不同形式的机械密封适用于不同的工作环境，如单端面机械密封适用于低压、低温、无腐
蚀介质的场合，而双端面机械密封适用于高压、高温、腐蚀介质等严苛的工作环境。

三、密封材料
机械密封的密封材料有很多种，如硅 carbide、碳素、陶瓷等。

不同的材料具有不同
的耐磨、耐腐蚀、耐高温等性能，需要根据工作环境不同的要求进行选择。

四、密封性能
机械密封的密封性能主要包括密封性能、耐磨性、耐腐蚀性等方面。

选型时需要考虑
产品的使用寿命，以及密封环的可更换性等因素。

五、价格因素
机械密封的价格因素也需要考虑。

不同品牌、不同规格同样的机械密封价格会有很大
的差异，需要根据设备使用位置和要求来选择适合的价格。

综上所述，机械密封选型需要从工作环境、密封形式、密封材料、密封性能和价格等
方面进行综合考虑和选择，以满足机械设备的要求，保证正常运行。

机械密封选型指南机械密封是一种用于防止液体或气体泄漏的密封装置。

它适用于各种工业设备，如泵、压缩机、搅拌器等。

选择正确的机械密封对于提高设备的可靠性和效率至关重要。

本文将介绍机械密封选型的指南，帮助读者了解在选择机械密封时需要考虑的因素。

首先，需要考虑的是工作条件。

包括工作温度、压力、介质等因素。

这些因素会直接影响到机械密封的材质选择。

例如，对于高温工作条件，需要选择耐高温的材质，如石墨、碳化硅等。

对于高压工作条件，需要选择能够承受高压的机械密封。

其次，需要考虑的是介质的性质。

包括介质的粘度、腐蚀性、固体颗粒含量等。

这些因素会影响到机械密封的密封性能和使用寿命。

例如，对于高粘度介质，需要选择能够适应高摩擦力的机械密封。

对于腐蚀性介质，需要选择耐腐蚀的机械密封。

此外，还需要考虑设备的运行速度和振动情况。

高速运转的设备会产生较大的离心力和振动力，这对机械密封的耐久性提出了更高的要求。

因此，需要选择能够承受高速和振动的机械密封。

另外，还需要考虑机械密封的结构类型。

常见的机械密封结构有旋转密封和静止密封两种。

旋转密封适用于旋转轴，如泵的轴封。

静止密封适用于固定部件，如管道的密封处。

在选择结构类型时，需要考虑设备的特点和使用条件。

最后，还需要考虑机械密封的成本。

不同的机械密封材质和结构类型的成本有所差异。

在选择机械密封时，需要综合考虑性能、品质和成本。

有时候，可能需要根据预算限制做出权衡。

总之，选择正确的机械密封对于设备的可靠性和效率具有重要影响。

在进行机械密封选型时，需要考虑工作条件、介质性质、设备的运行速度和振动情况、密封的结构类型以及成本等因素。

只有全面考虑这些因素，才能选择到最适合的机械密封。

机械密封的设计和选用
减少与腐
弹簧应加保
危险大的介质选用双端面密封；
耐酸机械密封
1—静环 2—动环 3—弹簧 4—波纹管
说明：
1)此结构为单弹簧聚四氟乙烯波纹管，外装式；2)摩擦副由氧化铝陶瓷与填充玻璃纤维聚四氟乙烯组对，填充聚四氟乙烯耐磨端与纯聚四氟乙烯波纹管制成一体；
3)弹簧可采用普通不锈钢制造
低摩擦系数和热膨胀系数的材
如选用热膨胀热油泵用高温机械密封1—内冲洗节流套2—轴套3—动环 4—金属
波纹管静环组件 5—导流套 6—填料密封
说明：
1)采用冲洗、冷却结构以提高冷却效果，设置导流套增加冷却面积； 2)采用金属波纹管结构；
3)采用低膨胀合金镶装石墨静环；。

机械密封型号手册机械密封是一种广泛应用于各种机械设备中的密封形式，它可以有效地防止介质泄漏和外部污染物进入机械设备。

机械密封的型号繁多，不同的型号适用于不同的工作条件和要求。

本手册将介绍几种常见的机械密封型号，以及它们的特点、应用领域和安装方法。

一、单端面机械密封（Type A）单端面机械密封是最简单的一种机械密封型号，由一个固定环和一个旋转环组成。

固定环安装在机器的静止部分，而旋转环则安装在旋转轴上。

这种密封型号适用于低压、低温和无腐蚀性介质的工作环境，轴的转速一般不超过3000转/分钟。

二、双端面机械密封（Type B）双端面机械密封由两个相互接触的面密封环组成，分别安装在旋转轴的两端。

两个面密封环之间的空间被填充着一个密封介质，通常是润滑油。

这种机械密封具有良好的密封效果和较高的工作可靠性，适用于高温、高压和有腐蚀性介质的工作环境。

三、外置式机械密封（Type C）外置式机械密封适用于需要频繁更换密封件的情况。

该型号的机械密封由一个固定环和一个旋转环组成，旋转环连接在密封机构的外部。

当需要更换密封件时，只需要拆卸外部的旋转环，而不需要拆卸整个密封机构，从而简化了更换密封件的过程。

四、波纹管式机械密封（Type D）波纹管式机械密封适用于高温和高压的工作条件。

该型号的机械密封由一对波纹管组成，波纹管的变形实现了有效的密封作用。

波纹管式机械密封具有良好的适应性和较高的工作可靠性，在高温、高压和有腐蚀性介质的环境中都能稳定运行。

五、混合式机械密封（Type E）混合式机械密封是一种结合了静密封和动密封的机械密封型号，它具有静态环和动静环两部分。

静态环用于实现静密封，而动静环则用于实现动密封。

混合式机械密封适用于中高温、高压和有腐蚀性介质的工作环境，具有较高的密封性能和工作可靠性。

六、旋转面机械密封（Type F）旋转面机械密封适用于高速旋转的轴。

该型号的机械密封由一个固定环和一个旋转面组成，旋转面由光滑的材料制成，可以与固定环接触并形成密封。

机械密封选型参数及分类(2013-12-27 10:00:00)转载▼标签：机械密封分类：车削密封件一、机械密封选型参数1.输送介质输送介质的物理化学性质，如腐蚀性、固体颗粒含量和大小、密度、黏度、汽化压力，介质中的气体含量以及介质是否易燃、危险或易结晶等。

2.安装密封的有效空问安装密封的有效空间包括D与L等。

3.工艺参数(1)密封腔压力P 密封腔压力指密封腔内的流体压力，该参数是密封选用的主要参数。

对新采购的泵，最方便、可靠的办法是向泵制造厂了解密封腔的压力数据;对现场在役设备，确定密封腔压力最简单的办法是在密封腔上装设压力表。

泵的类型估算公式后盖板带背叶片、耐磨环Pm=Ps 0.25(Pd-Ps)式中，Pm为泵进口压力，Pdo 为泵出口压力，下同后盖板带平衡孔Pm=Ps 0.10(Pd - Ps)带背叶片和平衡孔Pm = Ps后盖板有耐磨环，无平衡孔Pm = Ps 0.18MPa开式叶轮，无后盖板和平衡孔Pm= Ps C(Pd - Ps)注：C=0.1(最大叶轮直径)，C=0.3(最小叶轮直径)后盖板无耐磨环，无平衡孔Pm = Ps (大部分立式泵均如此)多级泵需根据平衡管、平衡盘和平衡鼓的布置来分析，密封腔压力有时等于进口压力，有时是某一中间级出[1压力．有时是泵的出口压力(2)流体温度T指密封腔内的流体温度。

(3)密封圆周速度V指密封处轴的周向速度，按下式计算：V=πnd/60 (1-6)式中 d——轴径，m；n——泵轴转速，r/min。

二、机械密封的分类1.推压型和非推压型密封(1)推压型密封指辅助密封沿轴或轴套机械推压来补偿密封面磨损的机械密封，通常就是指弹簧压紧式密封。

(2)非推压型密封辅助密封固定在轴上的机械密封，通常为波纹管密封。

表推压型密封和非推压型密封特点的比较项目推压型密封非推压型密封压缩单元单弹簧或多弹簧金属波纹管或橡胶波纹管轴的辅助密封动态静态尺寸范围/ram13～50810～305温度范围/℃-268～232-268～427压力范围/MPa≤20.69≤4.5特点尺寸范围大高压适宜于特殊设计适宜于采用特殊金属零部件少固有的平衡型结构静环磨损后，动环能自由前移高温价格一般较低金属波纹管密封一般价格较高橡胶波纹管密封一般价格较低。

机械密封分类1． 按用途分类1） 按应用的工业部门分类 有运输机械制造业、家用电器制造业、动力机械和泵制造业、化学工业及石油工业、国防工业、船舶制造业等部门用的机械密封。

2） 按应用的主机分类 泵、釜、离心机、风机、潜水电机、冷冻机、内燃机、冷却水泵、船用泵以及其他主机用的机械密封。

2．按作用原理及结构分类1）按密封端面的对数分，则有单端面机械密封，双端面机械密封和多端面机械密封．其中双端面机械密封又可分为轴向双端面机械密封及径向双端面机械密封。

2）按作用于密封端面流体压力为卸荷或不卸荷，可分为非平衡式机械密封、部分平衡式机械密封和全平衡式机械密封。

3） 按静止环装于密封端面的内侧或外侧，分为内装式机械密封及外装式机械密封。

4） 弹簧设置在流体之内为弹簧内置式机械密封，反之为弹簧外置式机械密封。

5） 按补偿机构的弹簧数量分为单弹簧式机械密封及多弹簧式机械密封。

6） 按弹性元件是否随轴旋转，则有旋转式机械密封及静止式机械密封。

7） 密封流体在密封端面间的泄露方向如与轴旋转的离心力方向一致，则为内流式机械密封，否则为外流式机械密封。

8） 按补偿环离密封端面最远的背面处于流体的低压侧或高压侧分为背面低压式机械密封及背面高压式机械密封。

9） 密封端面直接接触为接触式机械密封，反之为非接触式，其又可分为流体静压式和流体动压式机械密封。

10） 按有否波纹管零件分为非波纹管型及波纹管型机械密封、波纹管有液压成型金属波纹管、焊接金属波纹管、聚四氟乙烯波纹管和橡胶波纹管等几种。

3． 按使用工况分类1）由密封腔温度分为高温机械密封、中温机械密封、常温机械密封及低温机械密封．密封腔温度>200℃为高温机械密封；>80～200℃为中温机械密封；-50～80℃为常温机械密封；<-50℃则为低温机械密封。

2） 按密封腔压力可进行如下分类：当密封腔压力>15Mpa时为超高压机械密封；密封腔压力>5～15Mpa为高压机械密封，压力>0.8～5Mpa 为中压机械密封，常压至0.8Mpa为低压机械密封；当密封腔压力为负压时，则为真空机械密封。

机械密封件设计中如何选型机械密封结构型式的选择是设计环节中的重要步骤，必须先进行调查：①工作参数—介质压力、温度、轴径和转速。

②介质特性—浓度、粘度、腐蚀性、有无固体颗粒及纤维杂质，是否易汽化或结晶等。

③主机工作特点与环境条件—连续或间歇操作；主机安装在室内或露天；周围气氛性质及气温变化等。

④主机对密封的允许泄漏量、泄漏方向（内漏或外漏）要求；寿命及可靠性要求。

⑤主机对密封结构尺寸的限制。

⑥操作及生产工艺的稳定性。

1根据工作参数p、v、t选型这里p是指密封腔处的介质压力，根据p值的大小可以初步确定是否选择平衡式的结构以及平衡程度。

对于介质粘度高、润滑性好的，p≤0.8MPa，或低粘度、润滑性较差的介质，p≤0.5MPa时，通常选用非平衡式结构。

p值超过上述范围时，应考虑选用平衡式结构。

当p＞15MPa时，一般单端面平衡式结构很难达到密封要求，此时可选用串联式多端面密封。

υ是指密封面平均直径的圆周速度，根据υ值的大小确定弹性元件是否随轴旋转，即采用弹簧旋转式或弹簧静止式结构，一般υ＜20～30m/s的可采用弹簧旋转式，速度更高的条件下，由于旋转件的不平衡质量易引起强烈振动，最好采用弹簧静止式结构。

若p和υ的值都高时，可考虑选用流体动压式结构。

t是指密封腔内的介质温度，根据t的大小确定辅助密封圈的材质、密封面的冷却方法及其辅助系统。

温度t在0～80℃范围内，辅助密封圈通常选用丁腈橡胶O形密封圈；-50℃≤t＜150℃，根据介质腐蚀性强弱，可选用氟橡胶、硅橡胶或聚四氟乙烯成型填料密封圈：温度＜-50或t≥150℃时，橡胶和聚四氟乙烯会产生低温脆裂或高温老化，此时可采用金属波纹管结构。

介质浊度高于80℃时，在密封领域中通常就要按高温来考虑，此时必须采取相应的冷却措施。

2根据介质特性选型腐蚀性较弱的介质，通常选用内置式机械密封，其端面受力状态和介质泄漏方向都比外置式合理。

对于强腐蚀性介质，由于弹簧选材较困难，可选用外置式或聚四氟乙烯波纹管式机械密封，但一般只适用p≤0.2～0.3MPa的范围内。

Seal Material and Arrangement GuideARRANGEMENTSeal Material and Arrangement GuideIntroduction a Step by Step GuideSTAGE 1IDENTIFY FLUID DATASTAGE 3CHECK PERFORMANCELIMITSSTAGE 4CHECK SEAL DIMENSIONSCHECK MATERIAL AVAILABILITYREFER TO PRODUCTDATASHEETSTAGE 2IDENTIFY SEAL TYPESELECTED SEALSUITABLE SEALSThis guide is designed as a quick reference Material and Arrangement guide to complement John Crane CSelect ™Selection routine.When used without CSelect ™then it will be necessary to have the relevant Seal data sheets available to complete the Selection.1IntroductionSelection and ReferenceThis guide is designed to complement John Crane CSelect Seal Selection software. Follow the sequence to find the most effective seal for any of the listed fluids.Stage 1Over 500 commonly found fluids are listed alphabetically in the material guide, only the concentration and temperature of the fluid are needed to find the material, seal arrangement and other installation features.Alternative compatible materials are also shown to allow users who, for special technical or commercial reasons, wish to use materials and/or seal families other than the manuals recommendation, to check that their preference is equally suitable.A key to the Seal Selection page headings is provided on the fold-out page at the back. Stage 2The materials recommended in the material selection pages are the most cost-effective for the particular application. However, suitable seal types may have slightly different standard material combinations.By cross-checking recommended materials from the material selection pages with the standard and optional materials in the material availability chart in the seal data sheets, (not included in this document) appropriate material combinations canbe selected.Seal SelectionCheck ListFluid:.................................................sConcentration:..................................sTemperature:.....................................sSealed Pressure:..............................sShaft/Sleeve Size:............................sShaft Speed:.....................................sSeal Standard:..................................sSeal Chamber Depth:.......................sSeal Chamber Bore:.........................sDistance to NearestObstruction:......................................s 23Worked ExampleStage 3 – Seal Type Performance Evaluation for Seal Data SheetsStage 3 InstructionsUse the pressure/velocity graph and the PV multiplier factors to find the performance limits of the recommended seals.If a dual seal is required then a barrier fluid is needed, please consult John Crane for fluid control systems for tandem and dual seals.The choice of barrier fluid is dependent on individual plantoperating conditions and we recommend that you refer to your local John Crane Field Sales Engineer or John Crane office for specific recommendations.General guidance on barrier fluid selection is given on page 12.Stage 3Check Performance Limits from seal data sheetExample:Fluid: Acetic Acid T emperature: 25°C Pressure: 5 bar gShaft/Sleeve Diameter: 60 mm Speed: 2950 rpmFace/Primary Ring Material: CarbonSeat/Mating Ring Material: Aluminium Oxide CeramicFrom the Pressure/Velocity (PV) Limits chart, the maximum operating pressure at the required shaft sizeis 21 bar g. This pressure has to be corrected by the relevant multipliers from the PV Mulitplier Factors table. In this example the maximum pressure is given by:21 x 0.75 x 0.6 x 1.0 x 0.85 = 8.0 bar gTherefore the application pressure is within the pressure limit of the selected seal.T emperature limits for the bellows and any secondary sealing elements should also be checked to see that the application iswithin material limits.4Worked ExampleStage 4 – Seal Type Dimensional Data from Seal Data SheetsStage 4Check Installation DimensionsExample:Fluid: Acetic AcidShaft/Sleeve Diameter: 60 mm Recommended Seal: T ype 502Stage 4 InstructionsRefer to the relevant dimension tables and check the envelope dimensions to confirm that the sealwill fit the installation.5Key to Selection PagesFluid DataFluid Properties Hazard CodesTOXICCORROSIVEFLAMMABLEWATER REACTIONOXIDISINGEXPLOSIVESPONTANEOUSCOMBUSTION6Installation ArrangementsArrangementWherever possible the recommended sealing solution is a single seal, but if a fluidconcentration and temperature band present a significant hazard, the recommended solution will be for a single seal with a containment device, or, in extreme cases, a dual sealarrangement, with either a pressurised or unpressurised barrier fluid. Dual seal arrangements may also be recommended in cases where there are no suitable materials for a single sealsolution.S – Single SealA single seal mounted internallyA single seal mounted in a stationaryposition with the seat/mating ring rotatingD – Dual SealA dual seal installation where the seals are mounted in a back-to-back configurationwith a pressurised barrier fluid between seals A dual seal installation where the seals are mounted in a tandem configuration with a unpressurised barrier fluid between seals7Key to Selection PagesFlush and Neck ArrangementsFlushA flush is usually clean pumped fluid which is injected into the seal chamber. If necessary, the fluid may pass through a cyclone separator or strainer to ensure that it is clean and free from debris or abrasive matter. Certain applications may require a clean compatible fluid injection from an external source. There are five different seal flush configurations or piping plans, and the recommended flush is stated for each fluid concentration and operating temperature band. API Plan numbers are quoted for each flush configuration in the following examples,and more details of API plans are provided on page 44.F5 – Upstream PumpingA non-pressurised buffer fluid from an external source for use with an Upstream Pumping seal installation. The buffer fluid must be clean and compatible with the fluid being pumped.N1No special neck requirementsN3A moderate neck restriction is required in the form of a close clearance neck bushN4A severe neck restriction is required in the form of a lip seal or similar deviceN2An open large bore or open tapered seal housing is recommendedNeckIn certain circumstances a particular neck arrangement at the inboard end of the seal chamber may be recommended to control the fluid flow in or out of the seal chamber.Existing equipment may require modification to achieve the best seal performance.F1 – No FlushNo seal flush to be installed, i.e. dead ended seal chamber with vent.API Plan 02F2 – Product RecirculationRecirculation of the pumped product either from the pump discharge to the seat/face area of the seal, orfrom the seat/face areas of the seal to the pump suction.API Plans 01, 11, 13 and 21F3 – Clean FlushA flow of clean fluid to the seat/face area of the seal.The fluid can be either pumped fluid recirculated through a strainer or cyclone separator, or a clean compatible fluid from an external source.API Plans 12, 22, 31, 32 and 41F4 – Dual Seal, Pressurised BarrierA pressurised and circulated barrier fluid or gas from an external reservoir for use with a dual seal pressurised arrangement. The barrier fluid must be clean and compatible with the fluid being pumped.API Plans 53A, 53B, 53C, 54, 748Secondary ContainmentSecondary ContainmentAn external seal quench arrangement may be recommended for reasons of either safety, in the form of secondary containment, or to achieve optimum seal performance by use of a liquid or steam quench.The selection pages refer to seven different secondary containment arrangements, and explanations of these are given below.Q1No external quench facility requiredQ2 – Leakage ContainmentA quench gland which is designed to operate as aseal failure control device, diverting leakage to either a safe area drain or to a flare.The minimum requirement for failure control is afixed throttle bush, but its ability to contain liquid or vapour emissions is relatively poor. Dependingupon the fluid to be sealed, it is common practiceto up-grade the method of containment to ahigher integrity device such as an FS Lip Seal, ora floating or segmented bush. These seals can be installed in conjunction with an alarm or other seal failure indicator.For particularly hazardous fluids, it may bepreferable to up-grade the recommended quench arrangement from Q2 to Q6, a dual unpressurised seal arrangement.API Plan 61Q3 – Static QuenchA quench gland with provision for a static clean liquid quench such as an oil barrier.The quench gland should be sealed with a quench containment seal or lip seal, and the liquid level should be maintained at all times by a device such as a constant level oiler.API Plan 51Q4 – Intermittent QuenchA quench gland with provision for an intermittent clean liquid or steam quench.The quench gland should be sealed with a quenchcontainment seal or a lip seal, and the liquid quench flow automatically regulated by a quench control device to minimise wastage of quench liquid. The outlet from thequench gland should be piped to a safe area drain.API Plan 62Q5 – Continuous QuenchA quench gland which is fed with a continuous flow of liquid or steam.The recommended quench gland sealing device for a continuous flow of liquid is either a quench containment seal or a lip seal. For a continuous flow of steam therecommended quench seal is a segmental carbon bush, a floating bush, or a fixed throttle bush. The outlet from the quench gland should be piped to a safe area drain.API Plan 62Q6 – Unpressurised Dual SealAn arrangement where a non-pressurised buffer fluid from an external source is circulated between the inboard and outboard seals. Alternatively, a dry running mechanical containment seal could be used.The outboard seal materials must be suitable for sealing the pumped fluid.API Plans 51 and 52, 72, 75, 76Q7 – Splash GuardExternally mounted seals should be fitted with a splash guard incorporating a drain connection, in order to pipe any splash leakage to a safe area drain.Q2Q3, Q4 and Q5Q6Q7Note:Liquid quenches Q4 and Q5 must be piped in at bottom dead centre of the quench gland andout at top dead centre.Steam quenches Q4 and Q5 must be piped in at top dead centre of the quench gland and out at bottom dead centre.9Selection CommentsWhere appropriate, comments have been added to the selection pages beside the materials suitability chart. The comments are numbered, and a key to them is included on the fold-out page 44. Most of the comments are self-explanatory, but the descriptions for the most commonly used ones are as follows.1Refer to John Crane where no selection shown2Confirm Selection at Very High TemperaturesCertain fluids/applications may require special treatment at very high temperatures -please consult John Crane.3AbrasiveThe sealed fluid is likely to be of an abrasive nature. This has been taken intoaccount by the preferred sealing solution.4Atmospheric DepositsThe sealed fluid may leave deposits on the atmospheric side of the seal. It isrecommended that a Q3, Q4 or Q5 quench be used with an appropriate quenchmedium to prevent accumulation of these deposits.5CrystallisesIndicates that the fluid to be sealed is likely to crystallise on contact withatmosphere.6CloggingCertain fluids may be of a fibrous or abrasive nature, which may under normalcircumstances result in clogging of the seal. This has been taken into account by the preferred sealing solution.7Heated EnvironmentIndicates that the sealed fluid will solidify at normal temperatures, and therefore the pump/seal must be kept hot during operation and should be pre-heated beforeequipment start-up.8Avoid Springs in ProductCertain fluids may be of a fibrous or abrasive nature, which may under normalcircumstances result in clogging of the seal. A seal design where the springs are notimmersed in the fluid is preferred.9Stationary-Mounted SealA stationary-mounted seal with a rotating seat/mating ring is the preferred installationarrangement.10Vortex BreakerThe pump design should include a vortex breaker in the area of the seal.11Q5 – Steam QuenchA steam quench should be used. If the quench medium is not specified, water atambient temperature is recommended.12Q5 – Hot Water QuenchA hot water quench should be used. If the quench medium is not specified, water atambient temperature is recommended.13FDA Materials AvailableFor food-related or hygienic applications, Food and Drug Administration (FDA)approved materials are available and John Crane should be consulted if theseare required.14Refer Refinery SectionRefer to John Crane hydrocarbon processing brochure.15Refer Pulp & Paper SectionRefer to John Crane pulp and paper processing brochure.10Selection Comments16Refer positive Displacement Pump SectionFor positive displacement equipment solutions please refer to John Crane.17Consider Dry Gas SealDry Gas seals may be a more economic solution on this application.18Check Refrigeration Oil MaterialsRefrigeration oils present material compatibility problems, please check compatibility with the materials selected for this application.19Check Refrigeration Fluid MaterialsRefrigeration fluids present material compatibility problems, please checkcompatibility with the materials selected for this application.20Refer to John Crane for Higher Temperatures and Exceptions21Alloy C-276 Acceptable for SpringsSprings and adaptive hardware in Alloy C-276 can be used if indicated. Thin section components such as the edge welded metal bellows are not suitable and should not be used.22Quench fluid contained by a Mech. Seal above 80ºC Refer to John Crane pulp and paper processing brochure.23Dry = >98%Application is dry if concentration exceeds 98%.24Less than 40% GypsumGypsum content to be less than 40% if above consult John Crane.25From Wet ProcessRefer to pure Phosphoric Acid production.26From Thermal ProcessRefer to pure Phosphoric Acid production.27Pressure Surges C4 StageRefer to John Crane pulp and paper processing brochure.28See Seal Data Sheets for specialised face/primary ring materialsSpecialist materials may be appropriate. Consult relevant seal data sheet orbrochure for available materials.29Dry = No water in fluidWater is not present in fluid.30< 2000ppm H2S. Refer to John Crane for higher levels If application contains greater than 2000ppm H2S consult John Crane.11Dual and Multiple SealsIntroductionSelection of Dual SealsWhere a 'D' dual seal configuration isrecommended, it is necessary to select the seal type and materials for the outboard seal in addition to the inboard seal.Pressurised Dual Seals – F4Cross-Section of Pressurised Dual SealInboard Seal – Sealed Liquid SideThe recommended seal family and group material code for the inboard seal will bespecified in the seal selection pages. However,when selecting a seal type from therecommended family, it should be remembered that the operating pressure of the seal will be the difference between the barrier fluid pressure and the sealed fluid pressure. This barrier fluid pressure should be maintained at a minimum of 1 bar g or 10 per cent above the sealed fluid pressure, whichever is the greater – see Chart 1. Due to this low differential pressure, in normal operating conditions it is unlikely that a balanced seal type will be required. If, however, the pump or equipment to be sealed is likely to run dry with a consequential loss of sealed fluid pressure, it is essential that the pressure capability of the selected inboard seal is greater than the maximum pressure of the seal barrier fluid.For most applications it is necessary to ensure that the sealed fluid is contained and barrier fluid contamination minimised. T o achieve this theinboard seal must have a reverse pressureOutboard Seal – Atmosphere Side Generally, the seal family and materials recommended for the inboard seal are also suitable for the outboard seal. However, the pressure of the barrier fluid must be considered and may affect the outboard seal selection.If the sealed fluid is considered to be only moderately hazardous or corrosive it may be possible to select the outboard seal materials to suit the barrier fluid being used in preference to the sealed fluid. This option should only be considered where any migration of sealed fluid into the barrier fluid presents no hazard. If there is any doubt about this, John Crane should be consulted before the selection and use of alternative outboard seal materials.Unpressurised Dual Seals – Q6In the case of non-pressurised dual seals,generally, both inboard and outboard seals used will be of the same family and material code.Cross-Section of Non-Pressurised T andem Seal.Upstream PumpingAn Upstream Pumping seal, which is supplied as a cartridge, is a multiple seal combining the benefits of both a pressurised and a unpressurised dual seal.The materials selected for the inboard seal and the outboard seal should be suitable for the pumped fluid and the buffer fluid used.Ancillary Fluid Control Equipment Both pressurised and unpressurised dual seals require a fluid control system to manage the seal barrier/buffer fluid supply. The requirements of such a system are frequently tailored to suit the application and the operating plant requirements.John Crane should be consulted before theselection and use of any fluid control equipment intended for use on hazardous applications.Barrier Fluids/BufferSelection of a barrier buffer fluid is important to the safe and reliable operation of all dual and seal arrangements.As the fluid selected will be forming the barrier between the sealed fluid and atmosphere, the fluid must be non-hazardous. The fluid must be clean, i.e. not containing debris or abrasivedeposits. It must also be compatible with and at a temperature appropriate for the selected seal materials.In the case of a pressurised dual andUp-Stream Pumping seals, the fluid must also be fully compatible with the sealed fluid because migration of the barrier fluid will occur.Sealant PressureReverse PressureHydraulic Dia.Hydraulic Dia.Figure 11213Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.14Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.15Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.16Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.17Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.18Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.19Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.30Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.32Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.34Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.36Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.38Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.40Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.41Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.42Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.43Seal Material and Arrangement GuideNote 1: Please refer to fold-out page 44i/ii for keyto column headings, codes and comments.Note 2: q = Acceptable.Note 3: Seal performance limits must also be checked.44ivFind the temperature you want to convert (°C or °F) in the centre column (heavy type).Temperature Conversion Table45Inch Seal SizesSeal Size CodesMetric Seal Sizes。