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In World War II, helium mass spectrometry was used in Uranium enrichment plants for leak detection. This approach is still in use today, with some adjustments, as it is regarded to be one of the most accurate ways for locating leaks. Helium gas is utilized in this approach as a tracer gas. This occurs when helium leaks in/out of the tested product and enters the detector, where its partial pressure is recorded and shown on a screen. Leakage is detected using an instrument called a Helium Mass Spectrometer, which also measures the rate of leakage.

Principle of helium leak detector

Leak Detector works on the concept of a sector field mass spectrometer. Containers that need to be tested for leakage are usually filled with Helium and put in a vacuum chamber. The tracer gas helium is ionized in a vacuum after analysis. With the addition of voltage, helium ions are accelerated and then separated in a magnetic field. Using a particular detector, the ion current is converted to an electric current. Leak detecting units accelerate the current and display it on the screen. Helium concentration determines the measured current, which is equivalent to the measured leak.

What makes helium suitable for leak detection?

Due to its numerous advantages, helium is the ideal choice for leak detection purposes.

• Non-toxic and non-flammable
• Inert and non-condensed
• Low cost
• Due to its low atomic mass, it can easily pass through even very small leaks
• Present in the atmosphere, only in trace amount

Leak detection methods using helium mass spectrometer

There are two primary methods of testing: vacuum testing and pressure testing. The goal is to find the leak and determine how much or how fast it is leaking. When using either technique, it's vital to maintain circumstances that are comparable to what the system would encounter in real life.

As part of the vacuum testing, the leak detector is inserted into the system or product that has to be tested for leaks. In order to remove air from a system and create a vacuum, a pump is utilized. Helium is then sprayed on locations where the leakage is likely to occur. Spraying should be done with proper care to ensure that no portion of the body is skipped. As soon as the detector detects a leak of Helium, it alerts the user. This approach is also known as the spray probe method, or the spray probe technique.

Under pressure testing, the product must be placed within a vacuum chamber that has been properly constructed. Helium is pumped into the chamber, and the detector is used to check for leaks. This method is also known as the sniffer probe method. Helium filled system put in a chamber with a detector attached to a vacuum pump is another mode of this approach for determining leakage rate. If there is a leak, Helium will leak out of the pump and the detector will calculate the rate of leaking once the pump is running.

Helium mass spectrometry can be used in a variety of ways to discover extremely small leaks.

Helium leak detection technology is used to identify tiny leaks in a contained system. Other detection techniques may not be applicable due to operating limitations or if the leaks are so small that other techniques cannot find them. Due to its tiny size and inert nature, helium is an excellent choice for testing purposes. It has no effect on the materials in the item to be tested. Because of a variety of factors, helium is a preferable option as a tracer gas.

• Non-toxic, inert, and non-flammable
• The tiny atomic size makes it easy to pass through leaks

Helium is detected with a mass spectrometer or helium sniffer, however, it is also possible to utilize a residual gas analyzer. In comparison to other methods of finding leaks, helium testing is a thousand times more sensitive.

Various technologies

• SIMS 1915+

SIMS 1915+ is the ideal option for helium leak detection in pharmaceutical and medical device packaging systems. Vials, syringes, cartridges, and blister cards are some of the most common applications. Helium is commonly used to test the rubber stopper on a vial or the plunger on a syringe or cartridge assembly for leaks in parenteral goods. Sensitivity level as low as 1 x 10-10 mbar/L/sec may be measured with SIMS 1915+, which offers useful data sets instead of a basic pass/fail condition while allowing testing to be done at ambient temperature. It is important to note that each SIMS 1915+ Helium Leak Testing device is custom-built to meet client-specific requirements and package specifications.

• Cold storage package test systems

In an effort to retain product quality features, pharmaceutical and biologic firms continue to push for extended cold storage. In addition to requiring storage at temperatures below -20°C, many of these goods also require dry ice (-78.5°C) or liquid nitrogen (-200°C) for storage and delivery. However, many of the materials utilized in these package systems and responsible for preserving package integrity are not routinely evaluated at these temperatures. The glass transition state of elastomeric materials can be reached or exceeded at deep-cold or ultra-cold temperatures, causing leaks at low temperatures that would not otherwise be detected at room temperature.

• HSAM and Vial Filler

When it comes to helium-based leak testing systems, the Head Space Analyzer Module (HSAM) with vial filling assemble is a key component. As part of the HSAM, a probe measures the helium content in the headspace of a container system. With the optional vial filling assembly, previously sealed vials may be prepared for testing by replacing the headspace gas with 100 percent helium before the test is performed. After capping, this module can be used to prepare samples for testing or to prepare samples that have been kept for some time before testing. They may be used in conjunction with the VM-2 to get precise readings that can be included in flexible research designs.

• Sniffer Probe

This simple technique of tracer gas leak detection employs a sniffer probe to detect the gas's presence and locate the location of the leak. The tracer gas is initially applied to the part or system. With the sniffer probe, the operator then conducts a systematic search for probable leak spots. When it comes to finding micro leaks, sniff leak locating is quite successful. It is best used for examining smaller quantities of items. While the cost of sniffer testing depends on the kind of tracer gas utilized, it is a proven option for leak detection and localization.

• Package Test Fixtures

Outside the box, no leak testing is possible using a Helium Leak Detector. An HLD is only one component of a matrix that makes a useable system, just like a display is part of a computer system. Checking for quality packing material and sealing is a part of testing a package. By squeezing and holding it underwater, an operator checks for bubbles in a package using the manual leak testing method. The package retains atmospheric pressure when there are leaks.

• Calibrated Leak Standards

To support everyday usage, daily performance verification or system suitability tests, as well as planned certifications, LDA supplies full sets of calibrated helium leak standards. Each SIMS 1915+ has an inbuilt helium leak standard. Using a given leak rate, this technique releases a certain concentration of Helium. On each day of usage, it is utilized automatically by the instrument, or on-demand for autocalibration prior to analysis. Each external helium leak standard by LDA releases helium at a defined leak rate, similar to the internal leak standards. But instead of living inside the instrument, they attach to the test port in the same manner that a sample fixture would be installed in the system.

Some basic applications

• Glass Vials
• Pre-filled Syringes
• Bottles
• Blister Packs
• Foil Pouches
• Combination Products