A Practical Guide to Selection of Silicone Tubes for Process and Fluid-Transfer Lines
Picking the wrong tube rarely shows up on day one. It shows up three weeks later as a cracked wall near a pump head, a batch flagged for particulates, or a clamp that keeps slipping because the durometer was off. This guide to selection of silicone tubes is written from the floor up — the same checklist our engineering team at Makvin Polymer walks through before we recommend a grade to a customer. The goal is simple: help engineers, procurement managers and plant teams specify a tube that lasts the full service interval instead of failing mid-run.
Silicone gets specified across pharma, biotech, food processing, diagnostics and general industry because it stays flexible across a wide temperature band, resists ozone and UV, and can be sterilized repeatedly. But “silicone tube” is not one product. The right selection depends on five decisions, and getting them in the correct order saves money.
Start With the Fluid and the Application, Not the Catalog
Before you look at any spec sheet, define what the tube actually does. Is it carrying a sterile drug product, a food slurry, deionized water, a solvent, or low-pressure air? Is it static or flexing? Is it sitting in a peristaltic pump or just connecting two fittings?
This matters because the application sets every downstream choice. A vacuum line and a high-purity fill line may use the same outer diameter but completely different grades. Write down four things: the medium, the pressure, the temperature, and whether the tube flexes in service. Everything else hangs off those four answers.
Size: ID, OD and Wall Thickness
Inner diameter (ID) controls flow rate and how the tube seats on a barb. Outer diameter (OD) and wall thickness control pressure handling and how the tube behaves under a clamp or pump roller.
A thin wall flexes easily and is fine for gravity or low-pressure transfer. A thicker wall resists collapse and pressure but is stiffer to route. For barbed fittings, the ID should be slightly smaller than the barb so the tube grips. As a rule of thumb, undersizing the ID by a small margin gives a secure, leak-free connection without needing excessive clamping force.
Quick sizing reference
- Low-pressure / gravity transfer: standard wall, ID matched to barb
- Pump or pressure lines: heavier wall or braid reinforcement
- Tight routing / bends: check the minimum bend radius before committing to wall thickness
If you are still comparing dimensions, the extruded ranges on our silicone tubings page show the ID/OD combinations we run as standard, plus custom sizes for medical micro-bore work.
Hardness (Durometer): Soft Enough to Seal, Firm Enough to Hold
Silicone tubing is usually specified between roughly 50 and 70 Shore A. Softer tubing (around 50A) seals well on irregular fittings and flexes easily, which suits delicate pump applications. Firmer tubing (60–70A) holds shape better under pressure and lasts longer against roller fatigue.
A common mistake is over-specifying softness for a pump line — it feels nicer to handle but wears faster. Match durometer to the mechanical demand, not to how the sample feels in your hand.
Curing Chemistry: Platinum vs Peroxide
This single choice drives purity, cost and compliance. Platinum-cured silicone leaves virtually no curing by-products, so it is the default for pharmaceutical, biotech and high-purity food contact. Peroxide-cured silicone is more economical and perfectly suitable for general industrial transfer, insulation and lower-criticality lines.
If your fluid touches a patient, a drug, or a consumable, lean platinum-cured. If it is a workshop or utility line, peroxide-cured controls cost without compromising the job.
Compliance and Certification
For regulated work, the grade must carry the right paperwork — typically USP Class VI and FDA 21 CFR 177.2600 for pharma and food contact. Do not assume; ask for documentation. A tube that “looks medical” but has no traceability will not pass an audit. At Makvin Polymer every regulated batch is compounded in-house and lot-traceable, which is what auditors actually want to see.
Temperature and Chemical Exposure
Silicone holds its properties across a wide band — broadly −60°C to +260°C — which is why it survives autoclaving and steam sterilization that would destroy many other elastomers. Confirm both the continuous and the peak temperature of your process. Also check chemical compatibility: silicone resists water, mild acids and many polar fluids well, but is not the right pick for concentrated solvents or fuels, where a fluoroelastomer fits better.
Reinforced vs Non-Reinforced
If the line sees pressure or pulsation, a braid-reinforced silicone hose resists ballooning and kinking far better than plain tubing. For low-pressure transfer, non-reinforced tubing is lighter, more flexible and easier to clean. Match the construction to the pressure rating you actually need rather than over-building.
Putting It Together: A Selection Example
A vaccine fill-line customer came to us specifying soft, thin-wall tubing for a peristaltic pump. The fluid was sterile, the line flexed continuously, and the temperature was ambient. Following this guide to selection of silicone tubes, we moved them to a 60A platinum-cured grade with a slightly heavier wall. Pump life improved, particulate flagging stopped, and the USP Class VI documentation cleared their audit. Same family of product, correct grade — that is the entire game. You can review comparable grades on our silicone tubings page.
Frequently Asked Questions
What is the most important factor when selecting silicone tubing? The application and fluid come first. Once you know the medium, pressure, temperature and whether the tube flexes, the size, hardness, curing type and compliance fall into place logically.
What durometer is best for silicone tubing? Most fluid-transfer tubing sits between 50 and 70 Shore A. Softer grades seal and flex better; firmer grades resist pressure and pump-roller fatigue for longer.
Should I choose platinum-cured or peroxide-cured silicone? Choose platinum-cured for pharma, biotech and high-purity food contact because it leaves negligible by-products. Peroxide-cured is more economical and fine for general industrial use.
How do I size silicone tubing for a barbed fitting? Select an inner diameter slightly smaller than the barb so the tube grips securely without excessive clamping force, giving a reliable, leak-free seal.
Can silicone tubing be sterilized? Yes. Silicone withstands autoclaving and steam sterilization and holds its properties across roughly −60°C to +260°C, which is why it is widely used in sterile processing.
Conclusion
A good guide to selection of silicone tubes is really a sequence of decisions: define the application, size it correctly, match the hardness, choose the curing chemistry, confirm compliance, and check temperature and chemical exposure. Skip a step and you pay for it later in downtime or rejected batches. If you would like our engineering team to recommend a grade for your exact line, explore our silicone tubings range and request a sample or technical datasheet today.
