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Helium leak detection is referred to as the process of detecting leaks in various packaged or sealed systems by utilizing helium as tracer gas and measuring its concentration as it escapes due to leakage. A package system such as a vial that consists of a container and an elastomeric closure, is a good example. The vial is filled with helium and vacuum is applied. The quantity of helium that escapes from the package is quantified and expressed as a leak rate. A pre-filled syringe, a foil pouch, or a cold form blister card are some more examples of package systems. Each of these package types is designed to keep the pharmaceutical product enclosed while keeping out potentially harmful environmental pollutants like dust, bacteria, or even gases. The helium leak testing method can evaluate each of them.

Helium leak testing is widely utilized in the pharmaceutical and medical device industries because of its relevance in guaranteeing package integrity and quality. Now, let us see how these sectors benefit by using this technique.

1. Pharmaceutical Industry: The pharmaceutical industry has experienced enormous progress in terms of technological developments and drug delivery system innovations over the last two decades. However, such developments have created new quality assurance challenges for drug manufacturers. As a result, pharmaceutical manufacturers give major priority to both quality control procedures and pharmaceutical package leak detection.

CCI Testing is a leak detection technique that evaluates the capacity of container closure systems to maintain a sterile barrier against external contamination. These tests may be divided into two types: probabilistic test and deterministic test. Although probabilistic test methods like Bubble Tests and Dye Ingress were initially common, due to technological advancements, non-destructive approaches are now the preferred way for ensuring container integrity. Hence, pharmaceutical manufacturers are encouraged to switch to more dependable deterministic test methods, such as helium leak detection, which offer quantitative findings that are assured and precise. By using helium leak detection early in the development process, companies can improve the quality of their drug delivery system. This not only saves money and time, but also improves safety.

2. Medical Devices Industry: In the medical device industry, package integrity testing is important since product failure presents considerable risks to patients and healthcare professionals, as well as liability for manufacturers. Barriers between fluids or gases are frequently used in medical equipment. These barriers must be functional in order to safeguard the patient and, in many cases, the medical equipment. Some devices operate as channels for delivering or extracting fluids to or from specific parts of the body. If a leak develops along the channel, fluids might be supplied to the incorrect place by mistake or wrong fluids could be extracted, resulting in hazardous effects. As a result, medical device industries use various CCI test methods including helium leak testing to ensure package integrity.

Helium leak testing is the most common tracer gas method in the medical device industry. Helium or a helium-air combination is used to pressurize the test component within a vacuum chamber. The chamber enclosing the part is next evacuated, generating a vacuum that allows the helium to enter the chamber through any leaks. A mass spectrometer designed to detect helium takes a sample of the vacuum chamber and ionizes any helium detected. Even a small amount of helium is easily detected in this method.

The major reason for choosing the tracer gas technique by manufacturers is the necessity for high leak-detection sensitivity in particular medical device equipment applications. Product testing is a crucial part of the device production process in the medical industry. As quality requirements have gotten increasingly strict, leak testing has become increasingly important for medical equipment as well as pharmaceutical manufacturers.

The use of helium gas as a medium for leak testing during the gas diffusion process dates back to the 1940’s. The mechanism that enables leak testing using helium is the helium mass spectrometer which, at its core, is simply an air sampling tool that takes accurate measurements, using a series of pumps, to quantitatively measure the amount of helium in, around or leaking from a closed vessel or system is completed. Using helium as the “tracer” gas enables the user to discover and measure extremely small leaks. With so many available gases in our ecosystem, what is it about helium that makes it the ideal tracer gas for leak testing?

In the case of leak testing, size really does matter. Helium is one of the smaller molecules known to man and boasts of an atomic mass of 4 making it “light and smalll”. In comparison, only hydrogen is lighter than helium but as the passengers of the Hindenburg can attest, hydrogen displays some other explosive properties that may make the average laboratory technician shy away from its use. Because of its size, helium has the ability to flow through much smaller openings and at a much faster rate than other gas compounds. In technical parlance, you will often see this referenced as helium displays a high sensitivity rate as low as 1 X 10-10 cc/s. In laymen’s terms, this simply means that the small molecule size of helium makes it easy to “quantitatively detect and measure”.

While we note above the major disadvantage of using hydrogen as a tracer gas due to its explosive nature, helium is on the other extreme. Helium has three key characteristics that make its use easy and ideal. It is non-explosive, non-toxic and non-destructive. These characteristics insure that helium will not interfere with, or in any way impact, the type of material or vessel that you are testing. In most instances, the system being leak testing is constructed of plastic, glass or some type of metal. The inert and odorless nature of helium makes it chemically inactive when it comes in contact with any of these material types.

The presence of helium in the atmosphere tends to hold in the 5 ppm (parts per million) range. This feature helps to insure that false readings and general atmospheric interference in a non-factor when using helium gas as a testing agent.

Collectively, the characteristics of helium gas outlined above make it a very user friendly tool for leak testing. Couple these features with the easy availability and relatively inexpensive acquisition cost, helium has become the “first choice” method for leak detection in a wide variety of settings. Advances in the development of better mass spectrometers have led to more superior and more robust techniques and methods.