I SO 80369-7: Changing the Standard for Connecrs White Paper By: Levi Loesch, Product and Mat erials Engineer, DDL, I nc 1 I SO 80369-7: Changing the Standard for Connecrs
On Ocber 14, 2016, I SO form ally published 80369 Part 7, the long-awaited replacem ent everyone s fam iliar friend, I SO 594, the standard governing dim ensions and perform ance requirem ents of connecrs. The publication caps a m onum ental change in the fundam ental thinking surrounding devices that transfer liquids and gases in healthcare settings. Despite the Technical Com m ittee s desire disrupt as little as possible surrounding the current practices with connecrs, I SO 80369-7 still m akes m any significant changes. I n this paper, I ll highlight the changes that m ost significantly affect how one should construct their design verification plan, which are: stricter requirem ents on dim ensional and m echanical specifications, testing against slip and lock reference connecrs, m odifications assem bly and test procedures, and addition of guidance for perform ance of variable tests. As should be expected with changes of this m agnitude, there are m any nuances in the new standard that require som e interpretation. At DDL, we have had the opportunity work with m em bers of the I SO Technical Com m ittee and m any industry partners interpret these changes. Stricter Requirem ents on Dim ensional and Mechanical Specifications Prior the im plem entation of I SO 80369-7, the ubiquius use of connecrs m ade it possible for two incom patible devices be accidentally connected, which could lead patient injury. The principal goal of I SO 80369 is reduce the likelihood of these adverse events by introducing unique connecr designs for different m edical applications whose geom etry m akes it extrem ely difficult m ake these harm ful connections. One consequence of using the geom etry of the connecrs preclude m isconnections is that the connecrs now need be m easured ensure that they m eet the dim ensions and lerances of the prints in the standard. This differs dram atically from I SO 594, where as long as connecr perform ance could be proven against a reference standard, the dim ensions of the connecr largely did not need precisely m atch the standard. This is by far the m ost burdensom e new requirem ent resulting from the standards change and m any of our clients are incredulous learn that their thread design that has perform ed adequately m ust now be changed. I n addition stricter dim ensional requirem ents, there are also new restrictions on what m aterials m ay be used construct connecrs. The elastic m odulus of the m aterials m ust be greater than 700 MPa when tested in either tension or flexure per standard ASTM m ethods. Som e polym ers com m only used as connecrs do not m eet this requirem ent, including m any polyethylenes. Testing Against Slip and Lock Reference Connecrs W hen is it Required? The separation of I SO 594-1 for slip s and 594-2 for locking s created a convenient distinction between their separate requirem ents, but also a lack of clarity about if and when both sets of tests needed be perform ed. I SO 80369-7 contains both requirem ents within the sam e docum ent, but is still not explicit about when one should invoke the tests against I SO 80369-7: Changing the Standard for Connecrs 2
both slip and lock reference connecrs. This is an im portant consideration when qualifying a fem ale locking, as both m ale slip and locking s can easily be connected. The sim plest answer is that if a device with a fem ale locking is intended connect with a specific device that has a m ale locking, then the fem ale locking only needs be tested against the m ale locking reference connecr. I f the device s use is not as specific, or if it s uncertain, then both sets of requirem ents are in play. The table below lists the test requirem ents for each possible configuration. ISO 80369-7 Test Test Piece Type Slip Slip Reference Connecr Type Slip Slip Slip Fluid Subatmospheric Pressure Air Stress Cracking from Axial Load from X X X X X X X X X X X X X X X X X (*) X (*,^) X (*,^) X (*) X X X X The tests with a (* ) are only required if the fem ale locking under test isn t specifically indicated for use with a m ale lock device. I n addition, the tests with a (^ ) can be om itted through a worst-case analysis and justification. I n our discussions with representatives from the I SO Technical Com m ittee responsible for I SO 80369-7, we were able conclude that in certain circumstances, a rigorous exam ination of each test could lead a determ ination of a worst-case configuration. Modifications Assem bly and Test Procedures One of the critical elem ents of I SO 594 was a standardization of the rque and axial force used assem ble a test sam ple a reference connecr. I SO 80369-20, which is the st andard that defines how conduct the test m ethods, narrows the range of acceptable rque and axial force, utilizes the sam e assem bly values for every test and clarifies the assem bly procedure for products with floating or rotatable collars. 3 I SO 80369-7: Changing the Standard for Connecrs
The following table outlines the assem bly param eters of I SO 594 and 80369. Test Standard Test Method Assembly Parameters Axial Force (N) Torque (N m) ISO 594-1 All 27.5 0.1, Force, Torque, 27.5 0.12 ISO 594-2 Ease of Assembly 20 0.08 Stress Cracking 27.5 0.12 ISO 80369-7 Slip Connecrs 26.5 x 27.5 0.8 x 0.10 Lock Connecrs 26.5 x 27.5 0.8 x 0.12 I n addition changes in the assem bly param eters, m any of the tests have changed substantially as well; titles and test param eters have been m odified, new tests have been added, and the ease of assem bly test was elim inated because of its subjectivity. The following table com pares and contrasts som e of the m ost significant changes each test. ISO 594 Test Liquid Air Force Torque Ease of Assembly Stress Cracking ISO 80369-7 Test Equivalent by Pressure Decay Falling Drop Positive Pressure Liquid Sub-Atmospheric Pressure Air from Axial Load from None Stress Cracking I SO 80369-7: Changing the Standard for Connecrs Comments This is a new test which utilizes a pressure decay leak tester in order determine the pressure decay rate of the connection using air as the medium. The fluid leakage requirement in ISO 80369 is satisfied by performing either this test or the falling drop positive pressure liquid leakage test. The ISO 80369 test resembles the ISO 594 test without significant changes Rather than pulling a vacuum using a syringe and moniring for formation of bubbles, ISO 80369 specifies the vacuum pressure applied the connecrs and the rate of pressure loss is recorded. Use of a pressure decay leak tester is preferred for this test. There aren t significant changes the method; however, the acceptance criterion is more specific in ISO 80369, which specifies that the interface between the connecrs should not detach. The ISO 80369 test resembles the ISO 594 test without significant changes The ease of assembly test was not included in ISO 80369 because the analysis was o dependent upon test operar subjectivity. The ISO 80369 test resembles the ISO 594 test without significant changes The stress cracking preconditioning has not changed significantly; however, the method of detecting cracks has changed. In ISO 594, a visual inspection was performed. In ISO 80369, one the two fluid leakage tests is performed in order reduce the subjectivity of the test. 4
Addition of Guidance for Perform ance of Variable Tests Annex J in I SO 80369-20 contains specific instructions and guidance on how each test can be m odified in order obtain data of a variable (num erical) type, which m ay help reduce the sam ple size needed in order achieve the desired confidence intervals. For som e tests, e.g. sub-atm ospheric pressure air leakage, the change is trivial, only requiring one or two additional calculation steps. For others, like the positive pressure falling drop liquid leakage test, the apparatus used perform the variable test m ethod requires additional levels of control beyond what is needed perform the attribute test m ethod. The determ ination of whether or not utilize the variable m ethods is typically m ade on a case-by-case basis and takes in account the potential extra test m ethod validation work, fixturing and increased cost for tests which require m ore tim e and com plex equipm ent perform. Closing Caveats On Decem ber 23 rd, 2016, the FDA added I SO 80369-7 its list of recognized consensus standards. The FDA website states that the Agency will continue accept declaration of conform ity I SO 594 in support of prem arket subm issions until Decem ber 31 st, 2019. DDL will continue offer testing both I SO 594 and 80369 m eet the needs of our cusm ers. Finally, this paper is intended give a high-level overview of the differences between I SO 594 and 80369-7 and is not intended be a substitute for a com prehensive understanding of the contents of the standards and how it m ay affect design and testing. We at DDL always welcom e an opportunity discuss the nuances of the standards in greater detail, so don t hesitate contact us if you have any lingering questions or would like discuss an upcom ing project. Please visit www.t est edandproven.com for m ore inform ation about I SO 80369, or contact us at info@testedandproven.com. 5 I SO 80369-7: Changing the Standard for Connecrs