How to choose the right connector for low-pressure fluid handling
如何正確選擇低壓流體處理的快速接頭
Posted by Connector Tips Editor on Wednesday, April 15, 2015
by Grant Wilhelm, Senior Design Engineer, Colder Products Co.
選擇理想的管道連接器可以確保產(chǎn)品性能、增加易用性并為您的產(chǎn)品設(shè)計(jì)增加功能。這是一個(gè)三步指南。Selecting the ideal tubing connector can ensure product performance, increase ease of use and add functionality to your product designs. Here’s a three-step guide.
一系列產(chǎn)品的功能是通過(guò)小直徑管道傳輸液體或氣體——從醫(yī)療市場(chǎng)中的病床和體外診斷、打印機(jī)中的墨水管理系統(tǒng)和服務(wù)器機(jī)架中的液體冷卻系統(tǒng)到食品應(yīng)用和燃料管線中的調(diào)味品輸送在船舶和發(fā)動(dòng)機(jī)系統(tǒng)中。每個(gè)應(yīng)用中的主要需求是將流體從 A 點(diǎn)移動(dòng)到 B 點(diǎn)。 雖然這聽(tīng)起來(lái)很簡(jiǎn)單，但流體處理過(guò)程可能會(huì)因介質(zhì)特性、流速或壓力要求、物理空間限制、空氣夾雜和溢出問(wèn)題而變得復(fù)雜，用戶或環(huán)境安全問(wèn)題等等。
管道連接器是解決這些流體處理挑戰(zhàn)的關(guān)鍵組件。您選擇的連接器通常會(huì)在后一刻做出設(shè)計(jì)決定，從而對(duì)產(chǎn)品可靠性、性能和用戶接受度產(chǎn)生重大影響。有數(shù)以千計(jì)的連接器選項(xiàng)可供選擇，在不同的功能、材料和類(lèi)型中進(jìn)行選擇可能是一項(xiàng)艱巨的任務(wù)。為簡(jiǎn)化此過(guò)程，連接器選擇可分為三個(gè)步驟。遵循下面概述的每個(gè)步驟將有助于確保為任何需要使用管道處理流體的產(chǎn)品設(shè)計(jì)成功選擇連接器。
The tubing connector is a critical component in solving these fluid-handling challenges. Often bumped to a last-minute design decision, the connector you choose can make a big difference in product reliability, performance and user acceptance. There are thousands of connector options available, and choosing among the differing capabilities, materials and types can be an overwhelming task. To simplify this process, connector selection can be broken down into three steps. Following each step outlined below will help ensure successful connector choices for any product design requiring fluid handling with tubing. A range of products function by transferring liquids or gasses through small-diameter tubing—from patient beds and in vitro diagnostics in the medical market, ink management systems in printers, and liquid cooling systems in server racks to condiment delivery in food applications and fuel lines in marine and engine systems. The primary need in each application is to move fluid from point A to point B. While this sounds simple, the fluid-handling process can be complicated by media characteristics, flow rate or pressure requirements, physical space limitations, air inclusion and spillage concerns, user or environmental safety issues, and much more.
colder-produts-connector
圖 1：帶有內(nèi)置閥門(mén)的連接器有助于防止溢出。Figure 1: Connectors with built-in valves help prevent spills.
步驟 1：定義應(yīng)用的功能需求
1: Define the functional needs of the application
應(yīng)用的操作需求決定了管道和連接器的參數(shù)。接頭、魯爾接頭和快速斷開(kāi)接頭是低壓環(huán)境中常見(jiàn)的管道連接器。雖然每種都適用于某些應(yīng)用程序，但它們不一定可以互換。例如，在需要防止溢出的應(yīng)用中，帶閥的連接器是比魯爾接頭更好的選擇（見(jiàn)圖 1 和圖 2）。如果應(yīng)用涉及頻繁的連接和斷開(kāi)，設(shè)計(jì)用于長(zhǎng)期可靠性的快速斷開(kāi)是一個(gè)不錯(cuò)的選擇。The operative demands of your application determine the parameters for tubing and connectors. Fittings, luers and quick disconnect couplings are the most common tubing connectors used in low-pressure environments. While each is appropriate for certain applications, they are not necessarily interchangeable. For example, in applications where spill prevention is desired, a valved connector is a better choice than a luer (see figures 1 and 2). If the application involves frequent connecting and disconnecting, a quick disconnect designed for long-term reliability is a good choice.
Luer-connectors
圖 2：Luer 連接器的設(shè)計(jì)沒(méi)有截止閥。Figure 2: Luer connectors are designed without a shutoff valve.
總體而言，在分析您的應(yīng)用程序時(shí)，請(qǐng)考慮以下設(shè)計(jì)選項(xiàng)：
Overall, consider the following design options when analyzing your application:
- 管材——您使用的是什么尺寸的管材，包括內(nèi)徑和外徑？管子的內(nèi)徑 (ID) 尺寸通常是連接器尺寸的首要考慮因素。
- 端接類(lèi)型——常見(jiàn)的端接類(lèi)型是軟管倒鉤、壓縮接頭和推入式連接（見(jiàn)圖 3）。 - Tubing—What size tubing, both inner and outer diameter, are you using? The inner diameter (ID) size of the tubing is generally the first consideration for the size of the connector.
- Termination type—The most common termination styles are hose barb, compression fittings and push-to-connect (see figure 3).
Hose-barb-compression-fittings
圖 3：軟管倒鉤、壓縮接頭或按壓式連接終端適合您的低壓流體處理應(yīng)用。
Figure 3: Hose barb, compression fittings or push-to-connect terminations can be suitable for your low-pressure fluid-handling application.
- 軟管倒鉤端頭安裝在管道內(nèi)，并在一系列管道樣式和材料上提供安全連接。
- 單軟管倒鉤適用于較軟的管子，例如硅橡膠。帶有多個(gè)制作精良的倒鉤（具有鋒利邊緣且沒(méi)有分型線）的連接器提供了一種牢固的連接，在管道樣式和材料上不易斷開(kāi)。
- 壓縮接頭安裝在管子的外側(cè)，并使用螺母和套圈進(jìn)行連接。
- 按壓連接終端允許將管子推入接頭。
- 流量要求— 所需的流量和流量壓力是多少？允許的壓降是多少？連接器和閥門(mén)的壓降因制造商而異，有些設(shè)計(jì)比其他設(shè)計(jì)表現(xiàn)出更少的湍流和流動(dòng)阻力。請(qǐng)務(wù)必在計(jì)算中考慮截止閥和管道連接的影響。
- 尺寸——您需要知道軟管倒鉤的內(nèi)徑、推入式接頭的外徑以及管內(nèi)徑和壓縮外徑。
- 閥門(mén)選項(xiàng)——閥門(mén)的款式很多，流量和壓降各不相同。帶有集成閥的連接器可防止斷開(kāi)連接時(shí)溢出并防止空氣在連接過(guò)程中進(jìn)入系統(tǒng)。與提升閥式閥門(mén)相比，帶有精密齊平閥的連接器被認(rèn)為是真正的“干斷”或“非溢出”連接器，應(yīng)在迫切需要避免任何溢出、污染或引入時(shí)選擇連接時(shí)空氣進(jìn)入系統(tǒng)（見(jiàn)圖 4）。 - Hose barb terminations fit inside tubing and provide a secure connection over a range of tubing styles and materials.
- Single-hose barbs work well with softer tubing, such as silicone rubber. Connectors with multiple well-made barbs (featuring sharp edges and free of parting lines) provide a secure connection that is not easily disconnected over tubing styles and materials.
- Compression fittings fit over the outside of tubing and use a nut and ferrule to make the connection.
- Push-to-connect terminations allow tubing to be pushed into the fitting.
- Flow requirements—What is the required flow rate and flow pressure? How much pressure drop is allowable? Pressure drops across connectors and valves vary greatly by manufacturer, and some designs exhibit less turbulence and resistance to flow than others. Be sure to allow for the effect of shutoff valves and tubing connections in your calculations.
- Size—You will need to know ID for hose barbs, OD for push-in-fittings and tube ID and OD for compression.
- Valve options—There are many styles of valves, and their flow rates and pressure drops vary. Connectors with integral valves prevent spills upon disconnection and prevent air from entering the system during connection. Connectors with precision flush-face valves, compared to a poppet-style valve, are considered true “dry-break” or “non-spill” connectors and should be selected when there is a critical need to avoid any spills, contamination or the introduction of air into the system upon connection (see figure 4).
Poppet-style-valves
圖 4：帶有齊平閥的連接器將溢出減少到接近零。由于其設(shè)計(jì)，提升式閥門(mén)可能會(huì)溢出。
Figure 4: Connectors featuring flush-faced valves reduce spills to near zero. Poppet-style valves, by virtue of their design, can spill.
- 安裝選項(xiàng)——如何將連接配置到您的應(yīng)用程序中？常見(jiàn)的安裝選項(xiàng)包括面板安裝或直接安裝到 NPT 螺紋或端口。
- 連接器質(zhì)量——連接器的制造質(zhì)量水平會(huì)極大地影響其性能，也會(huì)影響美觀。在模制塑料接頭上，連接器主體上的分型線和模具缺陷（模具的兩半聚集在一起）應(yīng)該小，并且不會(huì)出現(xiàn)在第一個(gè)軟管倒鉤上。倒鉤或螺紋上的缺陷會(huì)導(dǎo)致泄漏。模制連接器的澆口（塑料注入模具的點(diǎn)）應(yīng)該沒(méi)有鋸齒狀邊緣，這些邊緣會(huì)卡住或撕裂手套或管道。 - Mounting options—How is the connection going to be configured into your application? Common mounting options include panel mount, or direct mounting into NPT thread or ports.
- Connector quality—The level of manufacturing quality of a connector dramatically affects its performance and can also play a role in aesthetics. On molded plastic couplings, parting lines and mold defects (where two halves of the mold come together) should be minimal on the connector body and absent from the first hose barb. Imperfections on barbs or threads can lead to leaks. The molded connector’s gate (the point where the plastic was injected into the mold) should be free of jagged edges that can catch or tear gloves or tubing.
第 2 步：將材料與應(yīng)用相匹配
Step 2: Match materials to the application
介質(zhì)類(lèi)型會(huì)影響連接器的選擇。選擇的連接器和管道材料需要與所使用的流體兼容。幸運(yùn)的是，連接器有多種塑料和金屬可供選擇（見(jiàn)圖 5）。除了考慮介質(zhì)兼容性之外，通過(guò)連接的流體的粘度和腐蝕性也應(yīng)該考慮到任何材料的決定。
The type of media influences the selection of a connector. The connector and tubing materials selected need to be compatible with the fluid being used. Fortunately, connectors are available in a ranges of both plastics and metals (see figure 5). In addition to considering media compatibility, the viscosity and corrosiveness of the fluid going through the connection should also be factored in to any materials decision.
流體處理連接器 fluid-handling-connectors
圖 5：連接器有熱塑性塑料、含氟聚合物、金屬和各種材料組合可供選擇，以滿足低壓流體處理應(yīng)用的性能和成本要求。
Figure 5: Connectors are available in thermoplastics, fluoropolymers, metals and various materials combinations to meet the performance and cost requirements of low-pressure fluid-handling applications.
連接器快速接頭還可能包括諸如 O 形圈和面板螺母之類(lèi)的組件，以及諸如彈簧之類(lèi)的內(nèi)部組件。還應(yīng)考慮這些部件與介質(zhì)的化學(xué)兼容性。例如，涉及漂白溶液的應(yīng)用將需要在流路中使用耐化學(xué)腐蝕的材料。Couplings may also include components such as O-rings and panel nuts, as well as internal components such as springs. The chemical compatibility of these parts with your media should also be considered. For example, applications involving bleach solutions will require a chemically resistant material in the flow path.
下面列出了通常可用的連接器和 O 形圈材料，以及使用這些材料的指南。
The following lists generally available connector and O-ring materials, plus guidelines for using these materials.
熱塑性塑料
- ABS —經(jīng)濟(jì)型醫(yī)用級(jí)熱塑性塑料，可承受伽馬射線和電子束滅菌
- 乙縮醛 —堅(jiān)固、輕便且經(jīng)濟(jì)的材料，在很寬的溫度范圍內(nèi)具有良好的剛性，具有韌性和耐用性
- 聚酰胺（尼龍）—抗磨損，在高溫下具有良好的機(jī)械性能
- PEEK（聚醚醚酮） ——一種工程熱塑性塑料，具有耐高溫、耐化學(xué)性和抗疲勞性
- 聚碳酸酯——耐某些化學(xué)品，透明且經(jīng)得起醫(yī)療應(yīng)用的消毒。
- 聚乙烯— 低成本、耐化學(xué)性、不透明的熱塑性塑料
- 聚丙烯 —優(yōu)異的通用樹(shù)脂，對(duì)溶劑和其他化學(xué)品的侵蝕具有很強(qiáng)的抵抗力
- 聚砜 —?jiǎng)傂浴?qiáng)度和耐化學(xué)性，它比大多數(shù)熱塑性塑料更能承受反復(fù)消毒和更高的溫度
Thermoplastics
- ABS—Economical medical-grade thermoplastic that withstands gamma and E-beam sterilization
- Acetal—Strong, lightweight and economical material that has good rigidity over a broad temperature range, with toughness and durability
- Polyamide (nylon)—Resists wear and abrasion, with good mechanical properties at elevated temperatures
- PEEK (polyetheretherketone)—An engineered thermoplastic with high-temperature, chemical and fatigue resistance
- Polycarbonate—Resistant to some chemicals, transparent and withstands sterilization for medical applications.
- Polyethylene—Low-cost, chemically resistant, opaque thermoplastic
- Polypropylene—Excellent general-purpose resin that is highly resistant to attack from solvents and other chemicals
- Polysulfone—Rigid, strong and chemically resistant, it withstands repeated sterilization and higher temperatures better than most thermoplastics
含氟聚合物
- PVDF（聚偏二氟乙烯） ——一種堅(jiān)韌的工程熱塑性塑料，具有平衡的物理和化學(xué)特性，使其適用于高性能應(yīng)用
Fluoropolymers
- PVDF (polyvinylidene difluoride)—A tough engineered thermoplastic with a balance of physical and chemical properties that makes it suitable for high-performance applications
合金
- 鋁— 具有高強(qiáng)度重量比的輕質(zhì)金屬，可提供經(jīng)久耐用的陽(yáng)極氧化處理
- 鍍鉻黃銅 —堅(jiān)固且美觀，這種金屬非常適合高壓和高溫應(yīng)用
- 壓鑄鋅 —重量比黃銅輕 20%，這種耐用且輕便的材料可承受高壓和高溫
- 不銹鋼— 具有出色的防銹性，常用于連接器組件，例如氣門(mén)彈簧 Alloys
- Aluminum—Lightweight metal with a high strength-to-weight ratio that is available with a durable anodized finish
- Chrome-plated brass—Rugged and attractive, this metal is excellent for high- pressure and high-temperature applications
- Die-cast zinc—Weighing about 20% less than brass, this durable and lightweight material withstands high pressure and high temperature
- Stainless steel—Offers excellent rust resistance and is often used for connector components such as valve springs
O 型圈選擇
- Buna-N —這是常見(jiàn)的 O 型圈材料，因?yàn)樗哂心腿軇┬浴⒛陀托院湍退?br />
- EPDM（乙烯-丙烯-二烯單體橡膠）—也稱為 EPR，這種材料具有出色的化學(xué)性能電阻
- FKM（氟烴） -已知其對(duì)熱，氧化，耐候性和耐臭氧性出色
- 硅都具有一個(gè)一樣好或更好的耐熱性為FKM; 醫(yī)用級(jí)有機(jī)硅還滿足 FDA 對(duì)生命科學(xué)應(yīng)用中生物相容性的 VI 級(jí)要求。 O-Ring selection
- Buna-N—This is the most common O-ring material due to its solvent, oil and water resistance
- EPDM (ethylene-propylene-diene- monomer rubber)—Also known as EPR, this material offers excellent chemical resistance
- FKM (fluorocarbon)—Known for its outstanding resistance to heat, oxidation, weathering and ozone
- Silicone—Has as good or better temperature resistance as FKM; medical- grade silicones also meet FDA Class VI requirements for biocompatibility in life science applications.
其他介質(zhì)考慮因素包括溫度范圍（-40 至 93o C）和連接器在應(yīng)用、存儲(chǔ)和運(yùn)輸過(guò)程中可能受到的壓力，以及可能使用的清潔溶液或其他環(huán)境暴露。測(cè)試潛在的產(chǎn)品材料總是一個(gè)好主意，以評(píng)估實(shí)際應(yīng)用中的材料性能。
Other media considerations include the range of temperatures (-40 to 93o C) and pressures the connectors might be subjected to in the application, in storage and during shipping, as well as cleaning solutions that may be used or other environmental exposure. Testing potential product materials is always a good idea in order to evaluate material performance in the actual application.
第 3 步：考慮增強(qiáng)的連接器功能
Step 3: Consider enhanced connector function
除了連接管道以促進(jìn)和控制流體流動(dòng)之外，當(dāng)今的連接器技術(shù)還可以為產(chǎn)品設(shè)計(jì)帶來(lái)更多的功能和性能屬性。例如，配備射頻識(shí)別 (RFID) 技術(shù)的智能連接器（見(jiàn)圖 6）允許在連接點(diǎn)進(jìn)行數(shù)據(jù)交換。通信耦合器傳輸?shù)男畔⒖梢员Ｗo(hù)設(shè)備、改進(jìn)流程甚至挽救生命。
In addition to connecting tubing to facilitate and control fluid flow, today’s connector technologies can bring increased functionality and performance attributes to product designs. For example, intelligent connectors equipped with radio frequency identification (RFID) technology (see figure 6) allow data exchange at the point of connection. Communicating couplers transmit information that can protect equipment, improve processes and even save lives. 
CPCs-IdentiQuik-line-connector
圖 6：支持 RFID 的連接器，例如 CPC 的 IdentiQuik 系列，可以通過(guò)將數(shù)據(jù)傳輸與流體處理相結(jié)合，為眾多產(chǎn)品設(shè)計(jì)增加價(jià)值。Figure 6: RFID-enabled connectors, such as CPC’s IdentiQuik line, can add value to numerous product designs by combining data transmission with fluid handling.
這些智能連接器通過(guò)在兩個(gè)分離的連接器之間發(fā)送 RFID 信號(hào)進(jìn)行通信。數(shù)據(jù)存儲(chǔ)在嵌入連接器或插件無(wú)源部分的 RFID 標(biāo)簽上。尋找標(biāo)簽的是一個(gè) RFID 閱讀器，該閱讀器位于連接器或主體的有源部分。當(dāng)兩個(gè)半耦合器彼此相距幾厘米時(shí)，閱讀器會(huì)檢測(cè)到標(biāo)簽，讀取它，并將標(biāo)簽數(shù)據(jù)發(fā)送到運(yùn)行系統(tǒng)的控制單元。控制單元還可以告訴閱讀器將新信息寫(xiě)入標(biāo)簽。
支持 RFID 的耦合器的一種應(yīng)用是通過(guò)確認(rèn)使用正確的墨水顏色來(lái)進(jìn)行商業(yè)打印機(jī)的墨水管理。
智能耦合還可用于確保產(chǎn)品在其使用壽命結(jié)束時(shí)退役，防止劣質(zhì)介質(zhì)損壞設(shè)備，強(qiáng)制使用一次性或有限使用的耗材設(shè)備，并確保在多端口環(huán)境中正確連接。
另一種為產(chǎn)品增加價(jià)值的連接器方法是多功能快速斷開(kāi)裝置（見(jiàn)圖 7）。這些連接器通過(guò)單個(gè)設(shè)備處理電力、信號(hào)和流體（液體和空氣）的傳輸。 These intelligent couplings communicate by sending RFID signals between the two separated coupling halves. Data is stored on an RFID tag embedded in the passive half of the coupling or insert. Looking for the tag is an RFID reader housed in the active half of the coupling or body. When the two coupling halves are brought within a few centimeters of each other, the reader detects the tag, reads it, and sends the tag data to the control unit running the system. The control unit can also tell the reader to write new information to the tag.
One application of RFID-enabled couplers is for ink management in commercial printers by confirming that the correct ink color is used.
Intelligent couplings can also be used to ensure a product is retired at the end of its useful life, to prevent inferior media from damaging equipment, to enforce single- or limited-use consumable devices, and to ensure correct connections in multiport environments.
Another connector approach that adds value to products is the multifunction quick disconnect (see figure 7). These connectors handle the transfer of power, signal and fluids (liquids and air) through a single device.
CPC-混合連接器 CPC-Hybrid-Connector
圖 7：多功能連接器，例如 CPC 的混合連接器，可以將媒體、氣體和電信號(hào)的連接整合到一個(gè)單元中。Figure 7: Multifunction connectors, such as CPC’s Hybrid Connectors, can consolidate the connections for media, gasses and electrical signal, into a single unit.
多功能連接器無(wú)需多次連接并有助于防止錯(cuò)誤連接。它們還簡(jiǎn)化了遠(yuǎn)程工具和設(shè)備之間的用戶界面。在醫(yī)療應(yīng)用中，這些連接器使技術(shù)人員能夠快速、安全地更換或更換模塊化工具、臍帶纜或手持件。
具有增強(qiáng)功能的連接器可為您的產(chǎn)品在市場(chǎng)上提供競(jìng)爭(zhēng)優(yōu)勢(shì)。通過(guò)選定的制造商提供，具有高級(jí)功能的定制連接器可以使您的產(chǎn)品更易于制造和使用。
盡管連接器在大多數(shù)產(chǎn)品中似乎是一個(gè)次要組件，但在您的設(shè)計(jì)過(guò)程中，它們不應(yīng)該是事后的考慮。連接器通常是用戶與您的產(chǎn)品的主要接口，它們可以在滿足產(chǎn)品性能和易用性目標(biāo)方面發(fā)揮關(guān)鍵作用。通過(guò)在連接器選擇中遵循上述步驟，您不僅可以成功地將流體從 A 點(diǎn)移動(dòng)到 B 點(diǎn)，而且還可以將您的產(chǎn)品移動(dòng)到更直觀、引人注目和功能性的設(shè)計(jì)。 Multifunction connectors eliminate the need for multiple connections and help prevent misconnection. They also simplify the user interface between remote tools and a device. In medical applications, these connectors enable technicians to quickly and safely change or replace modular tools, umbilicals or hand pieces.
Connectors with enhanced functions can provide competitive advantages for your product in the marketplace. Available through select manufacturers, custom connectors with advanced capabilities can make your product easier to manufacture and easier to use.
Although connectors seem like a minor component in most products, they deserve more than an afterthought in your design process. Connectors are often a user’s primary interface with your product, and they can they play a key role in meeting product performance and ease of use goals. By following the preceding steps in your connector selection, you will not only successfully move fluids from point A to point B—but you could also move your product to a more intuitive, compelling and functional design.
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