Blogs

What is helium leak detection?

The pharmaceutical industry has seen a significant rise in the use of pre-filled syringes in recent years. This demand is expected to accelerate over the coming decades. Pre-filled syringes offer benefits to the pharmaceutical industry in the form of reduced drug waste and increased product life span. Health care workers consider pre-filled syringes as an efficient, convenient and reliable drug administration method. However, they pose several challenges in manufacturing and require extensive testing.

Just like any other drug product, pre-filled syringes should be free from pyrogens and should be sterile. Not just that, they are expected to be biologically, chemically and physically stable throughout its shelf life. Considering the complex nature of these products, it isn’t surprising that there are many opportunities for it to fail to meet quality requirements. Defects in pre-filled syringes mainly depend on drug product design and syringe process design. Additionally, patient related issues are also an area of concern. Therefore, it is important for manufacturers to have knowledge and understanding of various tests involved to ensure patient safety.

Container Closure Integrity testing of pre-filled syringes

Sterility is the most important quality attribute associated with any pharmaceutical/ parenteral drug product. Container Closure Integrity (CCI) testing is one of the key tests performed by manufacturers so that the product is guaranteeing sterility and microbiological quality until point of use. Container closure integrity testing evaluates the ability of container closure systems to maintain a sterile barrier against possible contaminants that can deteriorate the quality of final pharmaceutical and biological products. There are multiple methods to conduct container closure integrity tests, each with its own set of benefits and limitations. For instance, techniques like dye ingress and microbiological ingress are destructive to the samples being tested. Such tests rely on statistically representative number of samples from the batch and assume that defects are uniformly present throughout the batch. On the other hand, deterministic methods are non-destructive in nature and can be used to test every unit from the batch.

Helium Leak Testing for Pre-Filled Syringes

Helium leak testing refers to the act of finding leaks in some type of enclosed or sealed system using helium as a “tracer” gas and measuring its concentration as it escapes due to leakage. Under this technique, the package is helium filled and subjected to vacuum. The amount of helium escaping the package is quantitatively measured with the help of a helium leak detector. The result is stated as a leak rate. Apart from being an effective container closure integrity test method, helium leak testing is also applicable in product design, product quality analyses, failure analyses and validation.

Why use helium as a tracer gas?

Helium is considered as an ideal choice of tracer gas because of the following reasons:

• Helium is non-toxic, non-condensable, non-flammable.
• It is inert, making it safe for use as it will not interact with the components being tested.
• The atom size of helium is really small, allowing it to breach pathways reliably and easily.
• Compared to other tracer gases, helium is less expensive and readily available.

What is helium leak detection?

Helium leak detection refers to the process of identifying leaks in an enclosed or sealed system using helium as a tracer gas. Helium is an ideal choice of tracer gas to find leaks because it is non-toxic, non-flammable, non-condensable, and its presence in the atmosphere is limited to 5ppm. Helium can pass easily through leaks because of its small atomic size. Additionally, helium is safe to use because it does not react with materials of parts being tested.

Overview of sniffer probe leak detection

Sniffer leak testing is a common tracer gas leak detection method that uses a sniffer probe to detect the presence of tracer gas and identify an area that is leaking. Under sniffer probe helium leak detection, helium is used as a tracer gas in combination with instrumentation to detect the presence of helium and more precisely an increase in helium due to the leaking part.

The prime objective behind conducting a sniffer probe leak detection test is to locate leaks in parts or systems so that they can be identified and repaired. The part or system is first pressurized with the tracer gas and then systematically scanned with a sniffer probe so as to detect possible leaks. Sniffer probe leak detection cannot be considered as a quantitative leak detection technique because the test results may vary depending on skill of the operator and the technique used. However, with the use of calibrated instruments, calibrated leak standards, and well-trained operators, quantitative results may be achieved. Sniffer leak testing is considered as an economical leak detection method that involves relatively low tool cost investment depending on the tracer gas used. Although sniffer probe leak testing is very effective in locating micro leaks, it may not be an ideal choice in high volume production environment.

How does sniffer probe leak detection work?

Sniffer probe leak testing begins by first filling the test object with tracer gas. The pressure inside the test object is increased to a pre-determined rate in order to create a differential in pressure. The outside of the test object is scanned using a sniffer probe that is connected to a leak detector. Because of the innate properties of helium, it readily penetrates through leaks and is sucked into the sniffer probe. The leak rate meter shows a display of the signal. On reaching maximum leak rate display, leak is located. Although the sniffer probe leak detection technique is very sensitive, its accuracy can be affected due to the amount of helium present in the atmosphere.

Advantages of Sniffer Probe leak detection

• Sniffer probe is very effective in locating minute leaks.
• Does not require expensive fixtures or test chambers and can be employed at low cost.
• Useful in testing small parts as well as complex systems.
• Higher test sensitivity can be achieved by increasing tracer gas pressure.
• Capable of detecting leaks in the range of 1.6x10-1 to 1x10-5 scc/s.

Container closure integrity plays an integral role in maintaining the stability of sterile pharmaceutical products. Most often, defects that cause vials to leak cannot be detected by a visual inspection process. Examples of such defects include microscopic cracks & scratches in the glass or temporary defects such as stopper pop-up that result in temporary container leakage. In such situations, helium leak testing ensures high sensitivity leak detection, which cannot be attained by many other leak test methods.

Overview of helium leak testing

Helium leak testing refers to the process of finding leaks in some type of enclosed or sealed system using helium as a “tracer” gas and measuring its concentration as it escapes due to leakage. It is an effective container closure integrity test method, aimed at evaluating the integrity of pharmaceutical and parenteral products. Helium leak detection works in the following way: Initially, the package is helium filled and subjected to vacuum. Then using a helium leak detector, the amount of helium escaping the package is quantitatively measured and stated as a leak rate. Apart from analyzing container closure integrity, helium leak testing is also applicable in product design, product quality analyses, failure analyses and validation. Helium leak testing is a flexible method that can be used with or without a test chamber in order to test "in-leakage" or "out-leakage", as well as leak location.

Why use helium as a tracer gas?

Helium is considered as an ideal choice of tracer gas because of the following reasons:

• Helium is non-toxic, non-condensable, non-flammable.
• It is inert, making it safe for use as it will not interact with the components being tested.
• The atom size of helium is really small, allowing it to breach pathways reliably and easily.
• Compared to other tracer gases, helium is less expensive and readily available.
• Its presence in the atmosphere is not more than ppm.

Glass vial leak testing using SIMS 1915+

Seal Integrity Monitoring System (SIMS) 1915+ is an ideal choice for helium-based leak detection of vials, blister cards, syringes, and cartridge systems. Compared to conventional vacuum bubble and dye penetration test methods, packages can be quantitatively tested using helium as the tracer gas that ensures higher levels of accuracy. Proven to be an affective leak detection method, SIMS1915+ can also be used for package design, tooling qualification, production line setup and on-going product quality monitoring. Designed specifically for the needs of pharmaceutical and medical device industries, SIMS1915+features an oil-free pump, detector and integrated power system that ensures quantitative analysis of package systems at sensitivity levels as low as 1 x 10 -10 cc/s at room temperature. Based on the client’s specific requirement, each SIMS 1915+ Helium Leak Testing instrument manufactured by Leak Detection Associates can be customized. Given below is a list of SIMS 1915+ Leak Detection System specifications along with add-on components.

• Helium Leak Detector Module (HLDM): Oil Free, Production version in Console Frame Assembly, with Stainless Steel working surface and Dual Test Port Manifold (allows concurrent use of VTFM & HSAM on HLDM unit).
• Vacuum Test Fixture Model (VTFM) – custom designed for use in testing of vial container samples
• Head Space Analyzer Module (HSAM) – Model VM-2 that includes three (3) Puncture Probes (two spares) for determination of Helium Concentration in the headspace of vial containers.
• Integral Calibration Chamber (w/ Calibrant Gas Flow Meter/Controller) provided for HSAM Calibration and a Universal Holder to be used for various vial diameters.
• Helium Filling Device specific for vial testing sample prep to enable vials to be filled with helium
• LT Low Temperature Add on units specifically designed for testing products under ultra-cold storage testing down to –140 °C.