Selecting the right connector can have a noticeable impact
By Colder Products Company (CPC)
From in vitro diagnostics to drug delivery, surgical tools to wound therapy, support surfaces and patient monitoring to home health and rehabilitation, fluid transfer through tubing is a critical function in medical devices throughout the patient experience. While tubing connectors may seem like a minor component in the overall device design, they are often a primary point of interaction for users and can have a big effect on product reliability, performance and ease of use. Therefore, it’s best to give them thoughtful consideration early in the design process.
There are thousands of connector options for design engineers to choose from and they offer different capabilities, materials and types. So how do design engineers make an informed decision? Start with these three major considerations.
Consideration 1: Define the functional needs of the application
The operative demands of your application will drive the type of tubing and connector you choose. Fittings, luers and quick disconnect couplings are the most common tubing connectors used in low-pressure environments. The specific application will determine which is most appropriate. Overall, consider the following design options when analyzing your application:
Tubing size — Consider both inner and out diameter
Termination type — The most common termination styles are hose barb, compression fittings and push-to-connect. Hose barb terminations fit inside tubing and provide a secure connection over a wide range of tubing styles and materials. Compression fittings fit over the outside of tubing and use a nut and ferrule to make the connection. And push-to-connect terminations allow tubing to be pushed into the fitting.
Termination Size — You will need to know the tubing ID for hose barbs, OD for push-in-fittings and tube ID and OD for compression.
Flow requirements — Consider the required flow rate and flow pressure as well as how much pressure drop is allowable. Be sure to allow for the effect of shutoff valves and tubing connections in your calculations.
Valve options – Connectors can have many styles of valves, and their flow rates and pressure drops vary. Do you need an integral poppet-style valve that mitigates spills upon disconnection or precision flush-face valves for true “non-spill” uses?
Mounting options — How is the connection going to be configured into your application? Common mounting options include panel mount, or direct mounting into threaded ports.
Connector quality — Manufacturing quality of a connector can affect its performance and aesthetics. Look to avoid defects in molded plastic couplings.
Consideration 2: Match materials to the application
The type of media will influence the selection of a connector. The connector and tubing materials selected need to be compatible with the fluid being used.
Couplings may also include components such as O-rings, as well as internal components such as springs, so you also need to take into account the chemical compatibility of these parts with your media.
Fortunately, connectors are available in wide ranges of both plastics and metals, and often with multiple o-ring and spring material options to suit your needs. Below is an abbreviated list of generally available connector and O-ring materials:
- ABS – Economical medical-grade thermoplastic that withstands gamma and E-beam sterilization.
- Polycarbonate – Resistant to some chemicals, transparent, and withstands sterilization for medical applications.
- Polysulfone – Rigid, strong and chemically resistant, it withstands repeated sterilization and higher temperatures better than most thermoplastics.
- PVDF (polyvinylidene difluoride) – A tough engineered thermoplastic with a balance of physical and chemical properties that makes it suitable for many high-performance applications.
- Aluminum – Lightweight metal with a high strength-to-weight ratio that is available with a durable anodized finish.
- Stainless steel – Offers excellent rust resistance and is often used for connector components such as valve springs.
- Buna-N – This is the most common O-ring material due to its solvent, oil and water resistance.
- Silicone –Medical-grade silicones meet FDA Class VI requirements for biocompatibility in life science applications.
Other important material considerations include the range of temperatures and pressures the connectors might be subjected to in operation, in storage and transit, compatibility with cleaning solutions that may be used in the environment, and potential mechanical loading the product may experience.
Consideration 3: Enhanced Connector Function
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 allow data exchange at the point of connection. Intelligent couplings can be used to help ensure a product is retired at the end of its useful life, to prevent the use of the wrong or inferior media, to enforce single- or limited-use consumable devices and to ensure correct connections in multiport environments.
Another connector approach that can enhance user experiences with end products is the multifunction quick disconnect. Multifunction connectors are designed to eliminate the need for multiple connections and help prevent misconnection. In medical applications, technicians can quickly change or replace modular tools, umbilicals or hand pieces connecting multiple fluidic, data and power lines in one single handed motion.
Connectors are often a user’s primary interface with your product, and they can help achieve your product performance and ease-of-use goals. By taking the preceding considerations into account early in your design process, you can create a more intuitive, compelling and functional design.
Sponsored content by CPC Worldwide