Why Use ISO 594 Test Assembly Machine

ISO 594 Test Assembly Machine is Needed for Valid Test Results.
This issue has many parts which will be addressed individually

ISO 594 Specifies Very Light Torque and Force Requirements.
When the ISO 594 Luer Fitting Standard was designed, the test method was targeted to replicate the lightest assembly strength needed to make a leak proof Luer connection. The torque and force requirements were set at the low end of the scale so that even a child could assemble the Luer connection and the seal would hold fast. It is known that as more force or torque is applied the seal will improve. Testing the Luer seal at low values automatically validates higher torque or force values.

ISO 594 Specifies Specific Values which are Verifiable.
When a test piece and reference fitting are assembled, the force and torque applied to the assembly should be recorded. Both force and torque are defined in ISO 594 Luer Standard as maximums and can be measured and shown to not exceed the ISO 594 required maximum. This is important because if the test is performed on an assembly that has been assembled in excess of the maximums, the test is invalid. If assembled with too much force or torque the probability that the assembly pass the test is greatly improved.

ISO 594 Requires Simultaneous Application of Both Force and Torque.
ISO 594 is cited below and in each of the citations the force and torque must be applied at the same time; simultaneously. Applied separately the force and torque have different results in the Luer Test Piece/Reference Fitting assembly and will exhibit different results under test conditions. To assure compliance with the ISO 594 Luer Standard, and repeatability of ISO 594 designated test results, the force and torque must be applied in unison.

Variation in Test Results Create Test Disputes.
If there is a contest between two entities about test results; when the test results are reporting disparate test results; check for adherence to the ISO 594 Luer Standard requirements. Assure that torque and force 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 594 Luer Standard requirements. As of the date of this post, many companies do not use a machine like the ISO 594 Test Assembly Machine. This holds true for both manufacturers and testing laboratories. The problem with that fact is that the 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 594 Luer Standard are flawed and worthy of being questioned.

How to Correctly Make the ISO Luer Test Piece/Reference Fitting Assembly.
The best way to correctly make the ISO Luer Test Piece/Reference Fitting assembly is to use the ISO 594 Test Assembly Machine. When used appropriately the ISO 594 Test Assembly Machine will eliminate the ISO 594 test violations because the ISO 594 Test Assembly Machine is designed specifically to make the ISO Luer Test Piece/Reference Fitting assembly. What makes the ISO 594 Test Assembly Machine so special is that it applies the force and torque simultaneously. This is a little tricky to accomplish, but the ISO 594 Test Assembly Machine does it well. The ISO 594 Test Assembly Machine has an automatic stop when the maximum torque is reached and has an arrangement to assure the maximum force is not exceeded. The degree wheel on the ISO 594 Test Assembly Machine is available for monitoring the occasional 90° maximum rotation specification.

If the requirement is only to have a few pieces tested, a limited testing requirement, we can make a referral to a laboratory which will make the ISO Luer Test Piece/Reference Fitting assembly in full accordance with the ISO 594 Luer standard.

Citations from ISO 594: Conical fittings with 6% (Luer) taper for syringes, needles and certain other medical equipment.
This Standard is supplied in two parts:
Part 1: General requirements
Part 2: Lock fittings

ISO 594/1 pp 5.2.1
Assemble the components by applying an axial force of 27.5 N for 5 s whilst applying a twisting action to a value of torque not exceeding 0.1 N-m to give a rotation not exceeding 90°.

ISO 594/1 pp 5.3.1.1
Apply the male fitting to the female reference fitting with an axial force of 27.5 N for 5 s whilst applying a twisting action to a value of torque not exceeding 0.1 N-m to give a rotation not exceeding 90°.

ISO 594/1 pp 5.5.1
Assemble the components by applying an axial force of 27.5 N for 5 s whilst applying a twisting action to a value of torque not exceeding 0.1 N-m to give a rotation not exceeding 90°.

ISO 594/1 Annex A.2
Assemble the components by applying an axial force of 27.5 N for 5 s whilst applying a twisting action to a value of torque not exceeding 0.1 N-m to give a rotation not exceeding 90°.

ISO 594/2 pp 5.2.1
Assemble the fittings by applying an axial force not exceeding 27.5 N while applying a torque not exceeding 0.12 N-m.

ISO 594/2 pp 5.3.2.1
Connect the male fitting to the female reference fitting by applying an axial force not exceeding 27.5 N while applying a torque not exceeding 0.12 N-m.

ISO 594/2 pp 5.6
Apply an axial force not exceeding 20 N together with a torque not exceeding 0.08 N-m.

ISO 594/2 pp 5.8.1
Assemble the fittings by applying an axial force not less than 27.5 N for 5 s while applying a torque not less than 0.12 N-m.

Initial Publication: May 6, 2009