Insight into Expanding Our Testing Technologies: Enhancing with the Most Sensitive Helium Leak Testing Method, Comparison of Two Manufacturers

Introduction

In the field of CCIT (Container Closure Integrity Testing), there are various test technologies available, each with different advantages and disadvantages depending on the application. Since we are focusing on two helium leak testers here, we will naturally place our emphasis on this technology. Helium leak testing has established itself across industries as a highly sensitive method for detecting leaks. This technology enables precise defect detection in many areas and can be very beneficial for CCIT when this level of sensitivity is needed. However, we will not go into detail today on the topic of MALL (Maximum Allowable Leakage Limit) and inherent package integrity, even though the strengths of helium leak testing shine particularly in these areas. I would like to emphasize, however, that tightness should be understood as a continuum. Within this continuum, different levels of tightness are relevant to the pharmaceutical industry. The upper detection range is more relevant, for example, for packaging material development or root cause analysis.

Our lab experience shows that the laser headspace analysis method using Tunable Diode Laser Absorption Spectroscopy (TDLAS), which has already been successfully established, is sufficiently sensitive for many of the areas mentioned above. This is also described in the paper by Christian Proff from Hoffmann-LaRoche, which we mentioned in a previous article, where TDLAS and helium leak testing are compared.

So, why the step toward helium leak testing?

The key advantage of helium leak testing, in our view, lies in its ability not only to detect the presence of a defect but also to provide comparability of defects through the leak rate. This gives you information about the size of a defect. While this is not scientifically accurate – further parameters such as defect geometry need to be known to determine the exact size – it provides a good first approximation of what is generally understood. In any case, it allows the measurement to be assigned to defect categories according to USP1207.

This information is made possible by the mass spectrometer connected to the helium leak tester, which “counts” the molecules passing through the defect and determines the helium gas flow.

TDLAS does not allow such direct measurement. We won’t dive into the other pros and cons between CO?-TDLAS and helium leak testing at this point, as we’re focusing on the devices mentioned.

Device Overview

In our lab, we recently tested two excellent laboratory devices, as seen in the image, from renowned manufacturers Pfeiffer Vacuum and Leybold. The devices are the ASM310 from Pfeiffer and the Phoenix Quadro from Leybold.

Both devices offer excellent capabilities for detecting leaks in parenteral containers and can significantly enhance our range of testing technologies. The helium leak test is particularly valuable for the defect models we create since it allows us to verify defect categories using the measuring device.

Pfeiffer Vacuum’s device stands out with its more compact design and lightweight construction, making it easier to transport. The detachable touch screen is a nice feature, allowing flexible operation. Additionally, it integrates easily into existing systems via a Bluetooth dongle, giving it a more modern touch.

The Pfeiffer device also seems quieter, and this impression is not misleading – the operating noise is about 8dB lower according to the specifications, though at 53dB for Leybold, neither is unpleasant or particularly loud. The higher noise level in the Leybold device is partly due to the rotary vane pump used.

In contrast, the Pfeiffer ASM310 uses a membrane pump as its fore pump. For our day-to-day lab work, this option is usually sufficient, and we’ve never experienced saturation of the membrane pump.

The Leybold device is larger and appears more robust, although both have a high-quality feel. Due to the use of an oil-sealed piston pump, it is also significantly heavier. However, this results in a higher helium pumping speed, which seems to contribute to faster stabilization of the measurement values. The Leybold device also offers an IO box for connecting external peripherals, which we did not take into account during this test. In addition to the touch screen that both devices have, the Leybold device has three mechanical control buttons. A useful feature is the ability to vent the system and break the vacuum by pressing the stop button for an extended period, making format or sample changes easier. However, this can also be set as an auto-function on both the Pfeiffer and Leybold devices, so that stopping the measurement automatically triggers ventilation. So, it’s a matter of personal preference.

Both devices feature an exhaust outlet for the measured test gas flow, allowing it to be directed out of the lab via a hose connection. This prevents helium from accumulating in the lab and raising the background level over time. Both devices also have a standard purging gas supply, such as nitrogen, for this purpose.

Test Conditions and Results

Our tests were conducted using prototype format parts that we manufactured ourselves at short notice. Once a device like this or a comparable one is used in our lab, custom sample holders with helium supply will be used.

Our tests focused on the usability and everyday practicality of the devices rather than measurement performance. Nevertheless, we were able to achieve surprisingly reproducible results with these simple setups. We may discuss this in more detail in a future article, but for now, the number of samples is too small for a thorough analysis.

Both devices are calibrated using internal test leaks.

Since the systems were introduced by field service representatives who kindly took a lot of time for us, we nevertheless weren’t able to explore all the functions in detail. There is also the possibility that further advantages and disadvantages could emerge with more extensive familiarity with the systems. One interesting feature in the Leybold device is the partial flow function, which allows measurements with high leak rates without overloading the detector. This feature was not shown to us on the Pfeiffer device, though it may also exist. In the practical use of a pharmaceutical lab, however, the need for this partial flow function should rarely arise.

Decision Making

We now face the exciting challenge of deciding which of these two excellent helium leak testers we will ultimately select for our measurement services. Both systems offer comparable outstanding performance, each with specific advantages that we have carefully analyzed during our intensive testing phase. It is extraordinary that, as an emerging test lab, we have had the opportunity to evaluate these advanced devices over an extended period and thoroughly test their performance in our specific environment. This extensive test phase has given us valuable insights beyond the usual evaluation processes. We hope that you, as the reader, have gained some insights as well. If you need services related to CCIT, please don’t hesitate to contact us.

• What technology comparisons would you like to see? Let us know in the comments. We will try to conduct further tests and reviews for you.

The advantages of both devices are so impressive that we would ideally like to add both to our portfolio. Each has its strengths, and we will make our decision based on the specific needs and priorities we currently have in our lab.

We look forward to announcing soon which device best fits our requirements and how it will further enhance our testing capabilities. We extend our sincere thanks to both companies for providing these devices. Special thanks go to Pfeiffer Vacuum and Leybold and of course their respective sales representatives Michael Frenz and Tobias Grotenrath for their trust and the opportunity to explore these advanced technologies so thoroughly.

Stay tuned for more updates and insights into our decision-making process and learn how be integral GmbH can support you comprehensively with CCI topics.