Specification builder · Tier B
Catheter and medical tubing kink resistance, flexural stiffness and flow-under-bend tester (low-force motorised test system with kink, bend and flow fixtures)
A low-force motorised test system that bends catheters, cannula tubing and infusion tubing around set radii or a closing loop while water flows, to find the radius at which they kink or lose flow, and measures their bending stiffness in a three-point bend fixture. It is bought by drug and device testing laboratories, local makers of IV sets, cannulas and catheters for batch release, and universities. The same frame can usually also run the catheter and IV-set tensile tests when grips are added.
What this equipment will do
- Sample types: single-lumen catheters and medical tubing, including IV cannula and infusion-set tubing, of outside diameter about 0.5 to 12 mm (EN 13868).
- Sample types: sterile urethral (urinary) catheters for the kink-stability test (ISO 20696 Annex G).
- Kink resistance: the tube is bent around a set of mandrels from 3 mm to 50 mm diameter to find the radius at which it kinks (EN 13868 short-term method).
- Flow under bend: water flow through the bent tube from a constant-head supply, reported as a percentage of flow through the same tube straight.
- Bending stiffness: three-point bend test giving stiffness (force per mm of deflection) and force at a set deflection.
- Motorised kink test: loop or bend closed by the machine at a set speed, with the bend radius at kink calculated by the software. (with the optional module)
- Long-term (time-dependent) kink test with several tubes held bent at the same time (EN 13868 long-term method). (with the optional module)
- Continuous electronic recording of flow and pressure against time and bend radius. (with the optional module)
- Flexural modulus of the tubing material when its dimensions are entered (ISO 178). (with the optional module)
- Distal tip stiffness and a stiffness profile at not less than 5 points along the catheter (ISO 10555-1). (with the optional module)
- Testing at body temperature (37 deg C), where catheter plastics are softer. (with the optional module)
- Peak tensile force of catheter sections and joints (ISO 10555-1) and tensile strength of infusion-set tubing joints (ISO 8536-4) on the same frame. (with the optional module)
Not covered: Balloon inflation, burst pressure, compliance and deflation time need the catheter balloon inflation and burst tester (ISO 10555-4).; Liquid leakage under pressure of catheter hubs and shafts (ISO 10555-1) needs a pressure leak tester, such as the balloon tester with its hub leak module.; Luer hub torque, unscrewing and overriding tests need the digital torque tester for medical connectors (ISO 80369-20).; Tubing outside and inside diameter and wall thickness need a measuring microscope or laser micrometer.
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Standards this specification draws on
- IEC 61010-1 Basic electrical safety of laboratory and test equipment; the frame and controller must conform.
- IEC 61326-1 EMC requirements so the controller and load-cell amplifier work reliably and do not disturb other lab instruments.
- EN 13868:2002 The European test method for kinking of single-lumen catheters and medical tubing (short-term and long-term methods, water as test medium); confirmed by CEN in 2023 and the main kink method this tester must perform.
- ISO 20696:2018 Sterile urethral catheters for single use; contains a kink-stability requirement with a test method in Annex G and a flow-rate test in Annex E.
- ISO 10555-1:2023 General requirements for intravascular catheters; its tensile and flow-rate tests run on the same frame, and it gives guidance on distal tip stiffness (force-displacement) testing.
- ISO 8536-4:2019 Infusion sets for gravity feed; it has no kink test of its own, but its tubing, tensile strength and flow-rate requirements (Annex A) define the IV-set tests run alongside flow-under-bend checks.
- ISO 178:2019 Three-point flexural test for plastics; used to give a comparable flexural modulus for tubing materials.
- ASTM F2606 Guide for three-point bending of balloon-expandable vascular stents and stent systems; covers flexural testing of catheter-based delivery systems.
- ISO 7500-1:2018 Verification and calibration of the force-measuring system of the test frame (accuracy classes).
- ISO/IEC 17025:2017 Competence of testing and calibration laboratories; sets the calibration traceability and records a testing lab must keep.
- 21 CFR Part 11 US rules for trustworthy electronic records and signatures; the reference most makers use to describe data-integrity functions of test software.
Common mistakes in tenders for this equipment
- Buying a general materials testing machine with no kink fixture, mandrels, loop guides or constant-head flow set-up; list every fixture and the flow equipment as separate priced items, and ask for a drawing of any kink fixture offered, since few makers list one as standard.
- Specifying a high-capacity frame (5-10 kN) with a single large load cell; catheter bend forces are often well under 1 N, so ask for a 10 N cell with stated accuracy from 1% of its capacity.
- Citing ISO 10555-1 or ISO 8536-4 as 'the kink standard': neither contains a kink method, so bidders tick compliance without the capability. Cite EN 13868 and ISO 20696 Annex G for kinking and ask for a clause-by-clause statement.
- Copying one maker's fixture drawing, exact mandrel list or named software module so only that brand complies; state the range of diameters, spans and forces needed instead.
- Accepting a factory calibration sheet instead of an ISO/IEC 17025 accredited certificate for load cells, displacement and mandrel dimensions, which leaves results open to challenge.
- Ignoring test conditions: water temperature, head height, conditioning of test pieces and 37 deg C testing must be stated, or results from different labs cannot be compared.
- Accepting a '21 CFR Part 11 compliant' claim without a live demonstration of audit trail, user roles, e-signatures and protection against data deletion.
- Asking for DRAP medical-device registration of the tester: it is laboratory test equipment, so this demand only confuses bidders.