ISO 80369-7 Small Bore Luer Connector Axial Torsional Test

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ISO 80369 Luer Test
ISO 80369-7 Small Bore Luer Connector Axial Torsional Test

ISO 80369-7 specified the design and performance requirements of small-bore connectors that are designed to be used in intravascular applications and hypodermic connectors. These connectors are essential components of many medical devices including needles and syringes, blood sampling systems, blood oxygenators, dialysis machines and more.

What Standards & Applications Relate to Testing per ISO 80369?

Each of the required test methods addresses different testing aspects. The standard evaluates connector closure quality through the application of forces, torques, and internal pressures that simulate use cases.

  • ISO 80369 establishes the criteria for small-bore connectors and tubing sets based on their application family
  • ISO 80369-2 focuses on connectors for breathing and driving gas applications
  • ISO 80369-3 sets forth the guidelines for enteral feeding connectors
  • ISO 80369-4 deals with connectors for urinary collection lines
  • ISO 80369-5 is dedicated to limb-cuff inflation systems
  • ISO 80369-6 focuses on neuraxial use
  • ISO 80369-7 focuses on performance requirements of intravascular and hypodermic male and female connectors for liquids and gasses
  • ISO 80369-20 is a common test method that provides a quality control measure that ensures no connector defects leave the manufacturing facility
  • ISO 594-1 & 2 separation force and unscrewing torque testing for luer tapers

How Is ISO 80369-7 Related to ISO 80369-20?

ISO 80369-7, combined with ISO 80369-20, describes the performance requirements for small bore medical Luer connectors. These small bore applications need to be compliant with the first standard so that they will reliably connect when being used. The IV therapy design of ISO 80369-7 includes systems that are designed to infuse liquid through intravascular or hypodermic applications and these connections must comply (meeting) this standard in order not have defects leave the manufacturing facility. Each required test method addressed different testing aspects within each requirement of construction quality, closure quality, torque control at assembly and after use as well as internal pressure testing.

Challenges of Testing to ISO 80369

One of the biggest challenges associated with testing to ISO 80369 requirements is the wide variety of different test setups needed to fully evaluate all the possible connectors and their applications.

A common approach to testing these connectors is through manual test assembly implementation. The consequences of manual testing is low test throughput or cost, significant lab inefficiency, and data repeatability concerns as test operators move from one manual test setup to the next. Semi-automation of the full testing process offers major benefits that include labor savings, material cost savings, improved data integrity, consistent data repeatability and reproducible results.

Semi-Automatic Test Machine Compared to Manual Test Machine

Comparing the use of a semi-automatic test machine and it’s impact on the testing process to that of a manually operated test machine will help you pick which mode of operation is right for you. 

Consequences of manual test machines:

  • Manual test machines require a loading fixture that is configured with deadweights and torque wrenches that must be repositioned to apply the required forces and torques.
  • When assembly and step by step testing is performed using different forms of test equipment, then the assembly needs to be removed from one unit and mounted in the second test fixture. Repeated seven times.
  • Manipulation of the test assembly, even if done very carefully, can have systematic and unsystematic effects on the test results.
  • Traceability of results is more complex and more limited
  • Risk of undetected operating errors is high
  • Labor is not free

ISO 80369-20

Performance Requirements

There are 8 different test methods that ISO 80369-20 describes. Each test type benefits from automating the testing process and additional savings accrue when they are all automated with one integrated solution. Incorporating a pressure sensor into the software reporting of a universal testing machine brings the opportunity to streamline test workflow by shortening the time needed in between setups.

Pressure Based Tests:

      • Annex B - Leakage by pressure decay test method – Luer connectors evaluated for fluid leakage performance are not to exceed a specified leakage rate while being subjected to an applied pressure of between specified levels over a hold period between 15 s and 20 s.
      • Annex C - Falling drop positive-pressure liquid leakage test method – Luer connectors evaluated for fluid leakage performance need to show no signs of leakage, sufficient to form a falling drop of water, over a hold period of 30 s to 35 s while being subjected to a specified pressure.
      • Annex D - Subatmospheric pressure air leakage test method – Luer connectors need to not leak by more than a specified amount while being subjected to an applied sub-atmospheric pressure of between a specified amount over a hold period of between 15 s and 20 s.

Axial Load Combined with Torsional Load Tests:

      • Annex E -  The first step in the stress cracking test method includes assembling Luer connectors by applying a precisely controlled axial force not less than the specified amount for 5s while applying (or combined with) the application of a controlled torque of not less than the specified amount.

Axial Load Tests:

      • Test Annex F - Resistance to separation from the axial load test method - Luer connectors need to not separate from the reference connector over a hold period between 10s and 15s while being subjected to a specified disconnection applied axial force between a specified load for Luer slip connectors, and a different load for Luer lock connectors. A universal test machine is needed with special fixturing to securely grip the sample. Also when this test is implemented with the test machine in manual mode, there is a good chance of damaging expensive reference connectors.

Rotational & Torque Tests:

      • Annex G - Resistance to separation from unscrewing test method - Luer lock connectors need to not separate from the reference connector for a hold period between 10 s and 15 s while being subjected to an unscrewing torque of a specified torque level. The main challenge of this test is to ensure that the equipment used to measure the unscrewing torque has the necessary tight control required for the test. Spring loaded manual torque wrenches are not satisfactory because the torque reading can get distorted when the sample suddenly breaks loose from the reference connector. Readings are also sensitive to the test speed that torque is applied at. A servo controlled torsional test channel or machine ensures that test data is consistent, repeatable and reproducible.
      • Annex H - Resistance to overriding test method – Luer lock connectors need to not override the threads or lugs of the reference connector while being subjected to a specified amount of applied torque of a certain amount over a hold period between 5s and 10s. This test will also require special fixturing in addition to a tensile or rotational test system. In manual mode, there is a good chance of damaging expensive reference connectors.
      • Annex I - Disconnection by unscrewing test method to verify that connectors, which can be connected and disconnected multiple times each day, can be successfully disconnected by the user. Performance requirements measure peak torque on twist off.

Results From Two Different Machines Can Create Disputes

Different machines, especially manually operated machines, can create different results. This can cause disputes between them. When test results are conflicting with one another, confirm adherence to the ISO 80369-20. This is why reqular calibrations are critical.

Performance Requirements:

      • Assure what torques and forces are applied simultaneously
      • Assure that the torque and force values are verifiable
      • Check to see if one or both parties in the dispute are violating the ISO 80369-20

Performance Requirements:

Test results may be invalid. If invalid test results were submitted to FDA for approval, the whole approval process may be flawed. Any test result that exceeds the limits of the ISO 80369-20 performance requirements are flawed and should be questioned.

Very Light Torque & Force Requirements

ISO 80369-20 replicates the lightest assembly strength needed to make a leak proof Luer connection. Torque and load requirements were set low so that anyone can assemble the connection and it’s seal would still hold. As additional force or torque is applied, the seals improve. Testing Luer seals at low loads automatically validates higher torque or force values.

Testing Must Be Verifiable

When a test sample and reference fitting are assembled, force and torque applied to the assembly is recorded. Force and torque requirements are defined in ISO 80369-20 and measured and confirmed to meet them. If the assembly has been assembled outside of the performance ranges, the test is invalid. If assembled with too little force or torque the seal will likely fail. If assembled with too much force or torque, the chance that the assembly will pass the test is significantly improved, but the test is invalid.

Force & Torque Tests Are Done Simultaneously

Force and torque must be applied at the same time; simultaneously. Applied separately, force and torque have different results in the Luer Test Sample/Reference Fitting assembly and will exhibit different results under test conditions. To assure compliance with the ISO 80369-20 performance requirements, and repeatability of ISO 80369 designated test results, force and torque must be applied in unison.

ISO 80369 3 Channel Axial Rotational Pressure Test Machine

Our 3 channel axial rotational pressure test machine (131AT-250-10-P), is a configuration with axial and torsion drives and a pressure sense channel. The vertical test frame is configured with 250 N (50 lbf) and 2 Nm (18 in-lbf) load and torque sensors. The frame is equipped with grips that clamp the test sample and incorporates optional mating reference connectors attached to the axial drive. Pneumatic lines enable pressure decay and subatmospheric air pressure leakage tests.

ISO 80369 Test Machine Test Sequence

Step one - The small bore connector is assembled with a customer provided standard reference connector under a predefined axial load and a predefined torque.

Step two - The system subjects the Luer connector to leakage or loosening tests, during which a specific pressure, force, or torque is applied for a commanded amount of time. The connector is classified as “Pass” if no leakage or loosening of the connection is detected.

Step three - that test sequence is completed, the machine returns to the first step and the process is repeated.

All data (forces, displacements, torques, angles, pressure) are recorded and become traceable for each individual Luer. The specimens do not have to be removed from the system after assembly, except for the pressure drop test, which requires horizontal alignment for testing. The only step during the test process in which the operator has to intervene manually is the positioning and alignment step. At that stage, the operator must ensure that the specimen is aligned and secured, while preventing deformation of the specimen. All other steps are performed automatically.

ISO 80369 Test Equipment

Our pre-engineered turnkey ISO 80369 test system is the best long term solution. It costs a little more upfront compared to a manual system but offers much better value in the long run. Manual machines require manual operation, as they don't have a controller. They are inherently risky and become expensive to operate. This is why we recommend a semi-automatic system.

131AT axial torsion test machine with upgradability from one channel to full functionality

131AT Configurations 131-250  131-X-10  131-X-X-P  131-250-10-P 
Measurement Axial Rotation Pressure Axial, Rotation & Pressure
Channels 1 1 1 3
Force 1100 N (250 lbf) X     X
Torsion 10 Nm (90 in-lbf)   X   X
Load Cell 250 N (56 lbf) X     X
Torque Cell 2 Nm (18 in-lbf)   X   X
Pressure Cell     X X
Footprint 12 in x 12 in X X X X