Silicone tubing looks like a commodity until the first batch fails. The tube clouds up inside a peristaltic pump, a hose clamp cuts through the wall, or the "food grade" certificate turns out to cover a different compound than the one that shipped. None of that shows up on a price sheet, which is why the cheapest quote is rarely the cheapest tube.
This guide covers the five decisions that actually change the part number you order: material, size, hardness, certification, and the specs you should insist on seeing in writing.
1. Start with the fluid, not the tube
Temperature and chemical exposure eliminate most options before price enters the conversation. Write down three things before opening a catalogue: the fluid, the working temperature range, and how the line gets cleaned.
| Fluid or condition | Check this first |
|---|---|
| Water, beverages, dairy | Food-contact certification, odour and taste transfer |
| Dilute acids and bases | Compatibility chart, concentration, contact time |
| Oils, fuels, solvents | Silicone swells here — evaluate EPDM, Viton or PTFE-lined hose |
| Steam or CIP above 130 °C | Continuous rating, not the peak rating |
One rule saves a lot of rework: silicone is excellent at temperature and flexibility, and poor at oils and fuels. If the fluid is a hydrocarbon, the honest answer is usually a different material.
2. Material: silicone, EPDM or PVC
All three get sold as "flexible tubing", and they behave very differently in service.
| Property | Silicone | EPDM | PVC |
|---|---|---|---|
| Temperature range | -60 to 200 °C | -40 to 120 °C | -10 to 60 °C |
| Flexibility | Excellent | Good | Fair, stiffens when cold |
| Oil and fuel | Poor | Fair | Fair |
| Transparency | Clear grades available | Usually black | Clear |
| Typical use | Peristaltic pumps, food and pharma transfer | Outdoor water, HVAC, coolant | Low-cost gravity lines |
If the tube touches product that will be consumed, stop comparing on price and confirm the certificate first. A cheaper compound with the wrong certificate is not a saving — it is a recall.
3. Size: ID, OD and wall thickness
Three numbers define a tube, and catalogues sometimes quote only one of them.
- Inside diameter (ID) — sets flow rate and is what the fluid touches. Pump heads are specified by ID.
- Outside diameter (OD) — sets what the clamp and the fitting grip.
- Wall thickness — (OD − ID) ÷ 2. Sets kink resistance and how much squeeze the tube survives.
A 1 mm wall and a 3 mm wall can share the same ID and behave nothing alike. Thin walls route more easily; thick walls survive repeated occlusion and higher pressure.
4. Hardness: what Shore A actually tells you
Hardness is the number most often copied from an old spec sheet and least often questioned.
| Application | Typical Shore A | Why |
|---|---|---|
| Peristaltic pump | 50–60 | Recovers its shape after thousands of squeezes |
| Food and beverage transfer | 60–70 | Balance of flexibility and pressure rating |
| Laboratory and analytical | 50–70 | Slips over fittings without splitting |
| Pressure lines | 70–80 | Resists expansion and clamp bite |
5. Certification is part of the specification
"Food grade" is a marketing phrase, not a standard. The document you want names one:
- FDA 21 CFR 177.2600 — food-contact rubber articles, repeated use
- USP Class VI — biocompatibility for medical and pharmaceutical contact
- ISO 10993 — biological evaluation, often requested alongside USP
- REACH / RoHS — restricted substances, mostly for EU-bound shipments
Ask for the certificate that covers the exact compound and the production site, not a generic PDF for the material family.
FAQ
Is silicone tubing food safe?
Only when the specific compound is certified to a food-contact standard such as FDA 21 CFR 177.2600. Platinum-cured grades are the usual choice for taste-sensitive products.
Can silicone tubing be used with oil or fuel?
Generally no. Silicone swells and softens in hydrocarbons; EPDM, Viton or PTFE-lined hose are the usual alternatives.
How often should peristaltic pump tubing be replaced?
Track hours of occlusion rather than calendar time. Pump makers publish a tube life for a given speed and pressure; replace at roughly 70–80 % of that to avoid a mid-batch failure.
Need a recommendation for a specific fluid? Browse the tubing range or send us the fluid, temperature and pressure and we will come back with two or three workable options.
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