A short guide to selecting quick release fluid connectors
Craig Forrester, Stäubli Connectors UK Manager, reviews the main factors that need to be considered and the options available when selecting quick release fluid connectors.
Selecting the most suitable fluid connector can significantly improve the safety, security and operational effectiveness of many industrial processes, for example temperature control on plastic injection moulds or fuel, air and oil circuits on engine test beds.
What are the main benefits that companies are looking for when choosing quick release fluid connectors?
Most companies want to speed up the connection/disconnection cycle on machinery and equipment to improve their productivity, so are looking for connectors that are quick and easy to use, even in difficult or inaccessible locations and will perform reliably and securely for many connection cycles. The range of connectors available is vast and includes clean break, flat face connectors that ensure no spillage on disconnection or any ingress of contaminants into the circuit, and connectors suitable for blind mating in inaccessible locations where a secure, positive feedback and robust locking system is required. Some of the latest designs of connectors can even accommodate a degree of misalignment between plug and socket, particularly useful for making remote connections such as liquid cooling systems on high power electronics in data centres.
Is safety improved?
Quick release connectors can make a significant improvement to both operator safety and circuit security. For example, using a connector with a secure two stage disconnection sequence on compressed air lines eliminates any danger of hose whip, the circuit is depressurised before the plug can be removed. A dry break, flat face connector, eliminating spillage and ingress, protects the working environment as well as the operator ensuring that the performance of the connected system remains unaffected by contaminants.
Cross-connections can be avoided by using keyed couplings that will only connect with the matching plug or socket or by placing the connectors on a multi-coupling plate that can only be connected in one position making all connections in one swift and secure movement.
Typically, which applications require the advantages of using quick release connectors?
Broadly, any applications where you are looking to reduce downtime. Speed, safety and security are the main reasons for using quick release connectors: companies want to be able to connect and disconnect systems easily without being concerned about any leaks, spillages or cross-connections. Typical applications cover a broad spread of industrial sectors from disconnecting and connecting pressurised air conditioning systems on armoured vehicles to brake lines on Formula 1 racecars - essentially any systems where the advantage of being able to swiftly connect and disconnect circuits safely, perhaps while still under pressure, is needed.
What are the main factors to be considered when selecting which connector to use?
Temperature, pressure, flow rate and the fluid or gas involved all have a major influence on the choice of connectors. Will the connection be made under pressure? What is the environment? Will circuits need to be connected individually or is there an opportunity to make additional savings by making all connections in one operation through the design of a multiple connection plate specifically for the application?
Standard, general usage, hydraulic connectors, chosen purely on pressure and flow capability, are often initially selected but rarely provide the best solution once all the requirements of a particular application are taken into account. A specific type of seal may be required, especially where aggressive fluids are involved or the shape of the connector body may be important if handling by remote control manipulators is required. In many instances space is at a premium so small compact connectors are preferable, and where weight is a major issue a lightweight aluminium connector or even one made from titanium might provide the best solution.
My advice is to involve your connector supplier from the start, at the design stage if possible. This will ensure that systems are constructed taking into account the need to connect and disconnect services as elements are either added to or removed from the system.
What are the main problem areas encountered in the use of quick release connectors?
Spillage and difficulty connecting are two of the main problem areas. Connectors that are unsuitable for the prevailing operating conditions are often initially selected, often almost as an afterthought when building the system and only later are problems encountered. Taking time at the design stage to consider the connection requirements can avoid all of these problems.
The specific application will determine which type of connector is most suitable and the type of locking system required. This might be bayonet locking for applications subject to vibration or screw or ball locking systems for high pressure circuits. Automatic connections often using multi coupling plates with guide pins and secure locking mechanisms can provide an effective solution for applications where connections are inaccessible or in hazardous environments where remote handling is necessary.
What industry standards for quick release connectors are recognised by users?
Recognised ISO interchangeability standards only really cover the basic types of connector being used in less demanding applications. Stäubli has always designed connectors for specific applications ensuring long life and reliable functionality even in the most challenging environments. Often the design involves plug and socket profiles beyond the industry standards.
What about the compatibility of connectors from different manufacturers?
This is an important consideration. Many users believe that the socket is the important part and that less attention can be given to the plug. But using different manufacturers' plugs and sockets can cause problems; the tolerances may vary, the seals used might not be suitable and lower quality materials could have been used in their manufacture, resulting in a connector that does not perform as required. Stäubli advises users to only use original Stäubli parts for both plug and socket. This ensures warranty coverage is maintained and avoids the potential danger that can result from the use of different plugs, even those claiming to copy the Stäubli profile.
What are the latest developments in connector technology?
Technical development is an intrinsic part of connector manufacturers' activities. Frequently a company will have a connection requirement that calls for adaptation of an existing product; this might be a change in sealing technology or a redesign to allow handling by remote manipulators. Technical designers work with the company to provide a solution that meets all the required criteria; often these developments will then be incorporated into the standard range of connector products for the benefit of others. At Stäubli Connectors' R&D department the major emphasis is on adaptation of connectors for specific applications, working closely with the customer to ensure that a connection solution is provided that is secure and robust, requires the minimum of maintenance and will operate reliably over many years.
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