ISO 594 | LUER TESTING

ISO 594 | PRIMARY TEST STANDARD FOR LUER FITTINGS

Conical Luer fittings are used in many medical devices, including hypodermic needles, syringes, catheters and infusion sets. A Luer fitting is the most common means of achieving a leak-free connection between two medical devices that carry small volumes of fluids.

There are two types of Luer fittings, Luer slip and Luer lock. A Luer slip fitting consists of a tapered cone and a mating tapered cavity. A Luer lock fitting consists of a Luer slip fitting with locking threads added. The Luer lock fitting creates a more secure connection and is therefore the more popular of the two. DDL tests both standalone Luer adapters and Luers which are components of various devices.

The governing standard for dimensional specifications and performance requirements of Luer fittings is ISO 594; Conical fittings with a 6% (Luer) taper for syringes, needles and certain other medical equipment. It consists of two separate standards, ISO 594-1 (Part 1: General requirements) and ISO 594-2 (Part 2: Lock fittings), first issued in 1986 and 1991, respectively. The first edition of ISO 594-2 allowed two different configurations of the female fitting thread–either full threads or two short lugs. However, other thread variants were being developed and introduced. In 1996, the European Community issued EN 1707, a European standard with the same title as ISO 594-2, but with two additional thread alternatives for the female fitting. In 1998, the second edition of ISO 594-2 was issued, containing the additional thread designs of EN 1707.

ISO 594 and EN 1707 contain 8 separate tests, some of which are only applicable to Luer lock fittings. The tests require that the sample be assembled to a particular precision steel reference fitting. The purposes of the various tests are outlined below:

  • Gauging: A dimensional check is performed using a calibrated plug gauge.
  • Liquid Leakage: Ensures that the sample Luer does not leak when pressurized with water.
  • Air Leakage: Ensures that the sample Luer does not leak when a vacuum pressure is applied.
  • Separation Force: Ensures that the sample Luer remains attached to the reference fitting when an axial load is applied
  • Ease of Assembly: Ensures that the sample Luer can be assembled with minimum axial force and torque.
  • Unscrewing Torque: Ensures that the sample Luer remains attached under a specific unscrewing (counter-clockwise) torque.
  • Resistance to Overriding: Ensures that the threads cannot be overridden by a specific screwing (clockwise) torque.
  • Stress Cracking: Ensures that the sample Luer does not crack when assembled for 48 hours.

In order to quickly turnaround Luer testing projects, DDL owns one of the largest collections of calibrated reference fittings in the testing industry. For repeatable and reliable assembly of the sample Luer to a reference fitting DDL uses a Medi-Luer ISO 594 Test Assembly
Apparatus. To further support the quality of the data DDL provides, we have validated our internal test methods and have added the ISO 594 tests to the scope of our ISO 17025 accreditation.

DDL has tested Luer fittings for many companies seeking to market their products in the United States, Europe, Asia and elsewhere. Many additional industry standards require testing per ISO 594 including ISO 7864, ISO 7886, ISO 8536, ISO 8537, ISO 10555, ISO 11040-4, ISO 11070, JIS 3209, JIS 3211, JIS 3223 and JIS 3228.

ISO AND EN TEST STANDARDS FOR LUER
FITTINGS

  • ISO 594-1 – Conical fittings with 6% (Luer) taper – Part 1: General requirements
  • ISO 594-2 – Conical fittings with 6% (Luer) taper – Part 2: Lock Fittings
  • EN 1707 – Conical fittings with 6% (Luer) taper – for syringes, needles and certain other medical equipment – Lock Fittings
  • EN 20594-1 – Conical fittings with 6% (Luer) taper – for syringes, needles and certain other medical equipment – Part1: General Requirements

ISO 80369 | SMALL-BORE CONNECTOR TESTING

In the 1990’s, concern grew as an increased number of medical devices utilized Luer connectors and a rising number of misconnections in the field were reported. In response to this risk, International Organization for Standardization (ISO) introduced ISO 80369 which consists of eight parts with one part (ISO 80369-1) addressing general requirements, six parts (ISO 80369-2 through -7) addressing specific applications and one part (ISO 80369-20) addressing general test methods. The overall intent of the standard is to reduce the risk of misconnection by creating six application-specific connector styles which cannot interconnect with one another. The application and general test method standards are in various stages of draft and publication.

ISO 80369-1 | TEST STANDARD FOR SMALL-BORE CONNECTORS FOR LIQUIDS AND GASES

ISO 80369-1, “Small-bore connectors for liquids and gases in healthcare applications – Part 1: General Requirements” became available at the end of 2010. The standard introduces its intent, defines the six connectors’ applications, provides terms and definitions and outlines the procedure that ISO will use to determine the final designs to be used in ISO 80369-2 through ISO 80369-7. The applications to be covered are as follows:

  • Part 2: Connectors for breathing systems and driving gases applications
  • Part 3: Connectors for enteral applications
  • Part 4: Connectors for urethral and urinary applications
  • Part 5: Connectors for limb cuff inflation applications
  • Part 6: Connectors for neuraxial applications
  • Part 7: Connectors for intravascular or hypodermic applications

One critical component to the ISO 80369 series is Annex B in ISO 80369-1. Annex B, titled, “Mechanical tests for verifying NON-INTERCONNECTABLE characteristics” provides test methods intended to demonstrate that two connectors intended for different applications cannot be connected. In an effort to address our customers’ needs to demonstrate compliance with Annex B of ISO 80369-1, DDL has purchased an axial/torsion (biaxial) test system that can perform the assembly procedure prescribed by the test method.

In an effort to address our customers’ needs to demonstrate compliance with the non-interconnectability requirements, DDL has purchased an axial/torsion (biaxial) test system that can perform the assembly procedure prescribed by the test method.

ISO 80369-2 to -7 | APPLICATION STANDARDS FOR SMALL-BORE CONNECTORS FOR LIQUIDS AND GASES

Each application deemed to carry unacceptable risk associated with unintended connections has been given a separate governing document. The applications to be covered are as follows:

  • Part 2: Connectors for breathing systems and driving gases applications
  • Part 3: Connectors for enteral applications
  • Part 4: Connectors for urethral and urinary applications
  • Part 5: Connectors for limb cuff inflation applications
  • Part 6: Connectors for neuraxial applications
  • Part 7: Connectors for intravascular or hypodermic applications

Each standard contains the dimensional requirements and acceptance criteria for the general performance tests contained in 80369-20. The most familiar method for performance characteristics of medical device connectors, ISO 594, will be replaced by ISO 80369-7 upon its publication, which improves upon many aspects of the standard.

ISO 80369-20 | GENERAL TEST METHODS FOR SMALL-BORE CONNECTORS FOR LIQUIDS AND GASES

ISO 80369-20 defines all of the general test methods which are referenced by the various application standards. Many of the test methods are based on those in ISO 594, but with modification to reduce the subjectivity of the tests (for example, performing a leakage test to determine the presence of stress cracking rather than a visual inspection) and to allow for variable testing which can reduce the required number of samples in order to achieve the same confidence intervals as an attribute test.

Please contact us today for more information on ISO 594 or ISO 80369 testing.