Exploring Alternatives to Flexible PVC Tubing
Polyvinyl chloride (PVC) tubing has been a stalwart in the medical device arena for nearly a century. PVC formulations have been utilized for general-purpose tubing as a cost-effective option due to their flexibility, transparency, and tendency to bond well to a broad range of materials. While PVC is useful, and certainly has a place in the medical device market, it may not always be the optimal choice for your medical application.
Flexible PVC is a tried-and-true material familiar to just about everyone but, as medical devices become more sophisticated, we need to look deeper into the material library to make sure we have the right material for the application. While flexible PVC is a great all-around choice in many ways it does have its limitations, especially when talking about operating temperatures, chemical compatibility, and UV/gamma degradation.
One of the main concerns with PVC is the presence of plasticizers, which impart flexibility and clarity, but can also leach into the fluid path. Near the end of the 20th century, many global health organizations cited one of the most common plasticizers, DEHP (di-plasticizers2ethylhexyl phthalate) as a potential health concern. While there are several DEHP alternatives, it is worth noting that even when PVC is formulated with a plasticizer other than DEHP, trace levels of DEHP are often a byproduct of the manufacturing process.
There are four (4) main alternatives to flexible PVC for medical device applications: Thermoplastic elastomers (TPE), thermoplastic urethanes (TPU), thermoplastic polyolefins (TPO) and silicone, a thermoset. Read on to learn more about non-PVC tubing alternatives.
Alternatives to flexible PVC tubing
Thermoplastic Elastomers (TPE)
TPE is a generalized term for thermoplastic tubing having high elongation values.
Why choose TPEs:
- High degree of flexibility and elongation which allow for excellent peristaltic pump tube performance.
- Depending on the material, some TPEs (those with rubber components in them) have a higher temperature range than PVC, which allows for the tubing to be used in a broader range of applications.
- May be customized to have a lower co-efficient of friction, which allows for a reduction of tackiness.
When TPEs might not be the best fit:
- Clarity requirements. TPEs generally range from translucent to opaque, which may limit the visibility of the fluid in the tube.
- TPEs with styrenic block co-polymers in them typically have a more narrow temperature range than PVC, which can limit their use in some applications.
- Since TPEs can be made from different materials, it may take more effort to determine which one is best for your needs.
Ideal application use selection for TPEs: TPEs are best used for peristaltic pumping applications and applications where tackiness is not desired (e.g., pinch valves) as they tend to be less tacky than most other options.
Thermoplastic Polyurethane (TPU)
TPUs are a specific subset of thermoplastic elastomers that utilize urethane polymers. The attributes outlined below demonstrate why TPUs can serve as a nice all-purpose alternative for flexible PVC.
Why choose TPUs:
- Abrasion resistance enables high durability, which allows for robust design capabilities.
- Good clarity allows a non-disrupted view of the fluid path.
- Can withstand temperatures slightly higher and lower than PVC, allowing for use in a relatively broad range of applications.
- Low gas permeability can limit diffusion into/out of the tubing, which may be beneficial for transfer of sensitive fluids.
- Favorable bond-ability with a variety of different adhesives, which allows for more freedom in design.
When TPUs might not be the right fit:
- Compared to PVC, TPUs that show favorable biocompatibility characteristics are typically higher in durometer than PVC thus they can be less pliable.
- Softer TPUs contain large amounts of plasticizers which may impact the biocompatibility characteristics of the material.
- TPUs are not ideal for pump tubing due to their high compression set which causes them to recover poorly over time.
Ideal application use selection for TPUs: TPUs are best suited for applications where durability and clarity are the main performance drivers and flexibility/compression set is less of a concern.
Thermoplastic Polyolefins (TPO)
TPOs are materials that generally contain ethylene, propylene, or a mixture of olefinic elastomers.
Why choose TPOs:
- Excellent chemical compatibility. They are typically the most chemically compatible/inert of the flexible PVC options and can withstand some of the harshest chemicals used in the medical industry.
- Generally, plasticizers are not added, which eliminates the risk of plasticizer leaching.
- Excellent clarity which allows for high visibility of fluid flow.
- Low surface energy/high surface smoothness which can help reduce microbial build-up.
- Low absorption/adsorption of aqueous fluids allows for tubing to be cleaned and reused while minimizing cross-contamination.
When TPOs might not be the best fit:
- Low elasticity makes them a poor choice for pump tubing.
- Limited flexibility which may limit tight bend radius requirements.
- Lower maximum temperature resistance compared to PVC, which may limit use for higher temperature applications.
Ideal application use selection for TPOs: TPOs are best used with alcohols and other aggressive chemicals, including harsh pharmaceuticals and when re-usability is desired.
Silicone Elastomeric Thermoset Material
Switching gears to a different type of flexible tubing, silicone is an elastomeric thermoset material.
Why choose silicone:
- Does not contain plasticizers which can improve the extractable and leachable profile.
- Typically have favorable biocompatibility characteristics.
- Translucent appearance enables visualization of fluid flow, although silicone is not as clear as PVC.
- Highly flexible, which can enable uninterrupted fluid flow in applications with tight bend radius requirements.
- Elastomeric properties make it a great peristaltic pump tube due to its low compression set.
- Maintains flexibility across a broad temperature range which makes it ideal for use in extreme conditions.
- Elasticity of silicone provides good sealing properties with hose barbs which can mitigate leaks; in contrast, other tubing materials may need additional products to create a secure attachment (e.g., Barb Locks, clamps, zip ties, etc.).
When silicone may not be the right fit:
- Permeation requirements. Silicone is much more permeable to gas than other materials, therefore gas diffusion may occur over time.
- Silicone can be difficult to bond. Ideally, silicone is bonded using a silicone-based adhesive.
Ideal application use selection for silicone: It is best used for pump/flexible applications and applications where favorable biocompatibility is key!
The importance of informed decision-making in material choice
Flexible PVC tubes have been used for decades due to their general-purpose abilities and low cost; however, designs for medical devices have become more specialized and complex, making it more important to ensure the optimal material is selected for the specific application, saving time and effort upfront.
At first glance, PVC will typically be the lowest-cost option for many medical device applications. However, choosing PVC for applications where other materials may be better suited could end up increasing costs over the long term due to product failures, excessive preventative maintenance requirements, and potential leaching.
There are many tubing material options available, and at times the choices can be overwhelming. We’re here to help! Contact us to tap into our material expertise and industry knowledge to guide you on your next project.
Saint-Gobain Performance Plastics Corporation’s Life Science (“Saint-Gobain”) products that are used as components in the manufacture of any Medical Devices (as defined by the FDA) are sold by Saint-Gobain only and exclusively to Medical Device manufacturers for use in the manufacture, assembly or distribution of their medical devices. Medical Device manufacturers, to whom Saint-Gobain sells components or for whom Saint-Gobain acts as a subcontractor for finished products, are solely responsible for determining whether their finished products are a medical device and complying with the appropriate certifications and registrations.
NOTE: This document is intended to provide information about the product to enable you to consider whether generally the Product meets your application need and is not intended to provide product specification. This document should not be considered a Product warranty or guaranty. To the extent this document mentions any tests done by Saint-Gobain, such tests are done under controlled laboratory circumstances and hence other factors in your use and application may impact such values. Product recommendations are based on a combination of industry knowledge, material science expertise and/or material testing data. Please reach out to Saint-Gobain Medical for further tubing recommendation information.
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