Buying a PTFE hose assembly correctly means confirming twelve items: medium and cleaning chemistry, working pressure at temperature per bore, the 3:1 PTFE safety factor, temperature envelope, smooth-bore vs convoluted construction, bend radius against real routing, vacuum duty, antistatic requirement, end fittings and crimp qualification, compliance certificates, assembly length/geometry, and documentation. Miss one and the failure typically appears at the crimp or as a liner crack months later. This is the step-by-step buying checklist; the parameter theory sits in the companion PTFE specifications deep-dive.
Why PTFE needs its own checklist
PTFE hose is not "rubber hose with better chemistry". The liner is stiffer, notch-sensitive when over-bent, cold-flows under clamping load, insulates electrically (a hazard with solvents), and cannot be field-modified after crimping. Half the checklist items below exist precisely because of these differences.
The 12-point PTFE hose buying checklist
1. List every medium the bore will see
Process fluid, concentration, temperature, plus CIP/SIP chemistry, sterilisation steam and flush solvents. PTFE's chemical resistance is near-universal (the practical exceptions are exotic: molten alkali metals, elemental fluorine at pressure), so this step mostly protects the rest of the assembly: braid and fitting alloys must survive the environment too, chloride-bearing washdown attacks 304 braid, so specify 316L there.
2. Working pressure at operating temperature, per bore
PTFE ratings fall steeply with size: a single-braid smooth-bore hose at ~200 bar for DN 6 drops to ~138 bar at DN 12 and ~69 bar at DN 25. Ratings are quoted at +20 °C and derate with temperature, at 200 °C budget roughly 60–70 % of ambient for single braid. Read the bore-specific, construction-specific table; never a family headline.
3. Apply the correct safety factor: 3:1
PTFE hose is qualified at a 3:1 burst-to-working-pressure ratio, class-specific and deliberate (braided rubber hose is 4:1, unreinforced ~5:1). Proof test ≈ 1.5 × WP per the ISO 1402 method. Confirm the ratio on the test certificate, and never treat burst as reserve.
4. Fix the temperature envelope
−70 to +260 °C continuous covers almost everything, but check both ends: cold-start embrittlement of jackets, and, at the hot end, the fittings and crimp interface, which usually limit before the liner. For steam, remember pressure and temperature are coupled (6 bar ≈ 165 °C, 18 bar ≈ 210 °C saturated); dedicated rubber steam hose to EN ISO 6134 with bolted safety clamps remains the reference for pure steam duty.
5. Choose the construction deliberately
Smooth-bore = default: lowest flow resistance, best cleanability and drainage, full CIP/SIP compatibility, MBR ≈ 6 × DN. Convoluted = for tight routing and continuous flexing: MBR ≈ 4 × DN, at the cost of flow and cleanability. Single vs double braid = the pressure class. Jacketed (rubber/thermoplastic cover) versions add abrasion and handling protection.
6. Check bend radius against the real routing
Map the tightest bend in installed and moving positions. A single over-bend creases the liner and the crease propagates into a crack under pressure cycling, the classic delayed PTFE failure. Solve geometry with elbow fittings, not force, and add ~20 % radius margin in dynamic zones.
7. Confirm vacuum duty
Suction, tanker offloading or condensing service needs a declared vacuum rating, construction-specific and verified by the ISO 7233 test method. Do not assume full-vacuum capability, especially at elevated temperature where the liner softens.
8. Decide the antistatic question explicitly
Flammable or combustible media, or ATEX zones (2014/34/UE) → antistatic carbon-loaded liner, product standard EN 16643, resistance verified per ISO 8031 with continuity across fittings. Standard PTFE insulates, and static discharge through the wall causes pinholes, and potentially ignition. The reverse exclusion: never carbon-filled PTFE for oxygen, oxygen service requires virgin PTFE with oxygen-clean assembly and certification.
9. Specify fittings and demand crimp qualification
Choose the interface (BSPP/ISO 228 parallel, seals on washer/O-ring; NPT or BSPT tapered, seal on thread, and NPT ≠ BSPT; JIC 37° flare; DIN 2353 24° cone; ORFS; sanitary Tri-Clamp DIN 32676 or DIN 11851, two different systems) and the alloy (316L for chemical/food/washdown). Then require the crimp specification: PTFE cold-flows, so hose OD, ferrule series and crimp diameter form one qualified system, verified by pull-off testing. Assemblies cannot be modified after crimping, order the exact length and geometry.
10. Compliance certificates, the correct ones
- FDA 21 CFR 177.1550 for PTFE in food contact (177.2600 is the rubber regulation, a common datasheet error).
- EC 1935/2004 + GMP 2023/2006; Regulation 10/2011/EU applies to PTFE as a plastic (it never covers rubber or silicone).
- USP Class VI plus extractables/leachables data for pharma; EN 10204 3.1 certificates for wetted metals. Certificates are tied to a specific medium and hose version, confirm your product, temperatures and cleaning chemistry are covered before ordering, not after delivery.
11. Define length, geometry and installation constraints
State overall length with tolerance, straight-leg requirements and orientation of angled fittings. Plan zero-torsion installation (align, then torque with two spanners), thermal-growth allowance on hot lines, and support spacing on long runs.
12. Documentation and replacement policy
Require proof-test certificates, crimp records, compliance declarations and batch traceability with every assembly, and set the inspection interval at purchase: braid condition (broken wires, rust staining, chloride pitting), any external seepage (= liner breach, immediate removal), fitting movement. In regulated service, replace on schedule, not on failure.
Quick decision table
| Duty | Construction | Key checklist items |
|---|---|---|
| Chemical transfer, drum unloading | Smooth-bore, 1–2 braids | 1, 2, 8 (solvents!), 9 |
| Pharma / biotech | Smooth-bore, 316L, jacketed option | 5, 10 (USP VI, E&L), 12 |
| Food & beverage | Smooth-bore, FDA 177.1550 | 1 (CIP), 10 |
| Hot hydraulics / phosphate esters | Smooth-bore, double braid | 2, 3, 6 |
| Tight routing, flexing | Convoluted, braided | 5, 6, 7 |
| Solvent / fuel in ATEX zone | Antistatic (EN 16643) | 8, non-negotiable |
Browse PTFE and chemical-resistant hoses or run a search for PTFE hose; fittings and sanitary couplings are in the industrial fittings category.
The five most common PTFE specification errors
- Transplanting rubber-hose habits. Quoting a 4:1 safety factor, assuming field-repairable fittings, or expecting rubber-like kink forgiveness — PTFE is a different engineering system on all three counts.
- One pressure figure for the family. The DN 6 rating is roughly three times the DN 25 rating in the same construction; orders written from the headline figure under-specify every larger bore.
- Standard PTFE on solvent duty. The insulating liner charges up and pinholes; if the medium can burn, the antistatic question (criterion 8) is not optional.
- Wrong food-contact citation. Datasheets regularly cite FDA 21 CFR 177.2600 (rubber) for PTFE liners, the correct reference is 177.1550. An auditor will notice even if the buyer doesn't.
- Ordering length without geometry. PTFE assemblies cannot be re-terminated or stretched; a missing straight-leg dimension or fitting orientation means a new assembly, not a workshop fix.
Cost: price the years, not the metre
PTFE assemblies cost typically 2–5× an equivalent-bore rubber hose. In aggressive chemistry, hot duty or regulated hygiene service they routinely run 5–10 years where rubber lasts 12–18 months, making PTFE the cheaper hose per year of service before counting avoided downtime. In plain mineral-oil hydraulics below 100 °C or abrasive slurry duty, PTFE adds cost without benefit (its abrasion resistance is poor), choose rubber there. For the material comparison, see PTFE vs silicone hose.
Work the checklist with our engineers
Send the twelve answers, medium, pressures, temperatures, routing, certificates required, and our engineering team selects the construction, matches qualified fittings, crimps to the documented specification and pressure-tests every assembly before dispatch. Browse the industrial hose range, download the technical catalogues, or request a quotation.