Difference between "Static Decay Test" and "Dynamic Leak Test"

<p>Hi,</p><p></p><p>Does anybody of you know the difference between the static decay test and the dynamic leak test? I know what the BSM performes in each case but I do not know, when to choose which test.</p><p></p><p>Thanks + regards</p><p>Ronald</p>


  • Wow, so much response. In the meantime I know that the static decay test was skipped with firmware update from 1.3 to 1.5 of the BSM. The reason was, that the outcome of both tests is equal, therefore one test is obsolet (regarding lokal Waters dealer).

  • Both are part of the Testing the system's fluidic integrity. Dynamic leak test: test to assess the flow path thorugh the binary solvent manager or auxiliary solvent manager. By monitoring plunger travel during constant pressure phase, it calculates teh leak rates of the primary and accumulators actuators. These leak rates can indicate whether the check valves, tubes, fitttings, or plunger seals are faulty. A rate below 0.150 uL/min (at least for nanoAcquity) for each actuators indicates a satisfactory test result (passed). STATIC DECAY TEST: performs a pressure ramp-up, and then monitors the pressure decay in the solvent manager to determine whether the check valves, tubes, fitting, or plunger seals are faulty. Anyway, if you have the operator's guide, this information is at page 6-60.

  • lei

    how can I get PDF manual?

  • If you are already registered to www.waters.com, you can log in with your user name and password and then search for nanoAcquity UPLC Operator's guide. You will see the file in pdf to dowload.

  • apologize, I tried to say download.

  • lizh


    This will be a long post my apologies, but  I am warning you at the beginning! But your interest deserves a full answer!

    I wanted to weigh in a little too.The nanoACQUITY uses a different test, as it test the flow controllers. I am assuming the question here is around the analytical scale instrument.

    A better explanation of the replacement of Static by Dynamic is that we "hid" the static leak test in service to discourage its use for new users, the dynamic does take longer, but is a far better test. The Dynamic Leak test is used for H-Class QSM and now available for both ACQUITY UPLC and I-Class BSMs. The reason we favor Dynamic is that it will give a fail or pass outcome, if it passes you can eliminate a leak. If it fails your leak suspicion is confirmed. Further, it measure dynamically and measures a real leak rate volume, not a calculated one. The volume is a value you can compare and understand, whether for a system or the pump alone. Note: As the newer ACQUITYUPLC I-Class has a wider backpressure range (than H-Class ACQUITY UPLC QSM or original ACQUITY UPLC BSM, both rated to 15,000 psi)  it must therefore have a higher leak rate.

    Here is some formal explanation:

    Static Decay Test and Dynamic Leak Test


    The static decay test and dynamic leak test are diagnostic tools that help identify issues with

    check valves, tubes, fittings, plungers, plunger high pressure seals or the vent valve on the

    BSM. These tests are not for use as a performance qualification. These tests should only be initiated if there are operational problems on the pump. He test is exercising the sealing.

    During the testing it is good practice to monitor the actual head pressures using the ACQUITY console window. Note it is necessary to set up the traces before starting the tests. It is recommended to at least display the Primary and Accumulator pressure traces for the side to be tested. The pressure scale should be fixed to have a low of 0 psi to a high of the test pressure and the time scale should be set to 5 minutes for the static decay test and 10 minutes for the dynamic leak test.

    Testing should only be performed using new, clean solvent and the system should be thoroughly primed. Any remaining air in the system can cause the testing to fail. Additionally, the tests should not be performed on new seals until they have been exercised for at least 30 minutes at 14000 psi, otherwise the test may fail.

    Static Decay Test

    The static decay test performs a pressure ramp up to the test pressure and then monitors the pressure decay. It reports a pressure decay rate in psi/min. This value is used to determine a pass/fail criterion with a threshold of 500 psi/min. It also reports a calculated leak rate in ul/min, percent of plunger stroke required to get to pressure and a final pressure at the end of the test.

    The static decay test is performed on one side of the pump (A or B) for a given test for QSM only a single pump. The test first pressurizes the accumulator pump head and monitors the pressure decay and then pressurizes the primary head and monitors the pressure decay again. The default initial test pressure is 14000 psi for the accumulator head and 12000 psi for the primary. The test pressure for the accumulator can be changed but the primary will always be tested at 2000 psi below the accumulator.

    The test fails if either head fails to reach its testing pressure, if the pressure decay is greater than 500 psi/min or if the primary head pressure increases during the accumulator head test.

    If a head does not reach its testing pressure this i...