Helium Leak Research Articles

Study of performance of aerostat envelope materials on the coast

In this article, the performance of several naturally aged envelope materials in Hainan, China, was studied. The results show that the outer layer contributes to the properties of the envelope materials, where PVF and PVDF are better candidates for a weathering layer than TPU and aluminum. Due to the superior water and mildew resistance of PVF and PVDF, the loss of tensile strength for 3216LV and FV1175 was slight, whose value reduced from 101.43 ± 5.45 Kgf/cm and 76.15 ± 3.81 Kgf/cm to 79.73 ± 6.40 Kgf/cm and 70.20 ± 6.57 Kgf/cm, respectively, when aging for 24 months with the helium permeability reduction from 0.8818 L/m2•day•atm and 0.6360 L/m2•day•atm to 0.2047 L/m2•day•atm and 0.2169 L/m2•day•atm aging for 18 months, in the case of FV1175 showed leakage after aging for 24 months due to delamination. However, the tensile strength of HV150 dropped from 82.13 ± 3.61 Kgf/cm to 15.22 ± 2.16 Kgf/cm at 24 months with helium leakage, owing to heavy mildew and degradation. Meanwhile, ETAV150 also exhibited a decreased tensile strength of 57.92 ± 1.32 Kgf/cm after 6 months aging, 32.8% lower than that of the original sample, and showed leakage when aging for 12 months. This research provides a theoretical guidance for the structural design and screen of envelope materials for aerostat used along the coast.

Low-Temperature Sandwich Structure Wafer-Level Hermetic Packaging via Three-Layer Simultaneous Bonding for 3-D Microsystems

A sandwich structure, which is stacked by a wafer-level copper–copper (Cu–Cu) thermocompression bonding and a silicon–silicon (Si–Si) direct bonding, has been investigated for potential application as a hermetic seal in 3-D microsystem packaging. First, the bottom and middle layers are prebonded by hydrophilic Si direct bonding. Oxygen plasma is employed for surface activation. Then, the prebonded wafers and the top wafer are bonded via Cu thermocompression bonding at a bonding temperature of 300 °C and a bonding force of 8000 mbar for a duration of 1 h. The entire bonding process of the three layers has borne only one heating procedure, which could effectively reduce the residual stress after bonding. Cavities are etched to a volume of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$21.4\times 10^{-3}$ </tex-math></inline-formula> cm3 following the MIL-STD-883E standard prescribed for microelectronics packaging. The helium leak test demonstrates that 96.8% of the samples present a superior leak rate smaller than <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.7\times 10^{-8}$ </tex-math></inline-formula> atm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> cm3/s. Moreover, the interfacial adhesion energy between the Cu–Cu bonding interface and the Si–Si bonding interface was projected at 16.4 ± 4.6 J/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{m}^{2}$ </tex-math></inline-formula> and Si breakage energy. The results hold great promise for 3-D microsystem wafer-level packaging.

Container Closure Integrity of Vial Primary Packaging Systems under Frozen Storage Conditions: A Case Study.

As the complexities of the pharmaceuticals needed to prevail over serious diseases continue to grow, the need for technologies to enable their efficient storage and delivery are as essential as ever. Lately, drugs such as vaccines, proteins, and stem cells are increasingly requiring frozen storage to maintain their efficacies before use. Notably, the advent of cellular therapy products has invariably elevated the need for cryopreservation and frozen storage of cellular starting materials, intermediates, and/or final product. The container closure integrity (CCI)-which is a major requirement for aseptic or sterile packaging systems-at these extremely low temperatures has not been fully understood. For vial-based systems particularly, the commonly used rubber stoppers are expected to lose their elastic properties below their glass transition temperatures, suggesting a potential temporary loss of sealability under frozen storage conditions and posing a risk to CCI. The measurement of the CCI at these conditions such as -80°C is therefore critical; a process that can be very challenging. Previous works had explored the use of Oxygen Headspace Analysis to measure CCI at low temperatures. Here, we present the evaluation of the CCI of rubber-stoppered aluminosilicate glass vials (Valor®) and plastic vials (Crystal Zenith®) using the helium leak CCI test method at -80°C, with correlation to residual seal force (RSF). The results and their implications are then discussed with regard to the suitability of certain packaging components as frozen storage container closure systems.

Analysis of three-layer gasket performance affected by flange surface

Gaskets are components that play a very important role in piping connections to prevent leakage. Several factors affect the performance of the gasket, one of which is the contact surface of the flange. The quality of the contact surfaces in the connection also influences the leakage rate of each connection, therefore the gasket sealing performance is assessed by the rate of leakage that occurs. As a result, the surface roughness of the flange has an effect on sealing. This study examines the capability of a three-layer corrugated metal gasket to prevent leakage when the outside layer thickness and flange roughness are adjusted. The feature of three-layer corrugated metal gasket was elucidated using the finite element analysis (FEA) and experimental method. The leak rate was tested using a helium leak quantity test experimentally. The gasket was constructed with oxygen-free copper (C1020) as the outside layer and SUS304 as the base layer, and it was structured in a three-layer pattern with no bonding. A mold press was used to make the gasket. The simulation method applies finite element analysis software to investigate the correlation between contact stress, contact width, surface thickness and surface roughness. The projected results matched the experiment results fairly well. A three-layer corrugated metal gasket shows improvement capability to prevent leakage than a single gasket (standard). The gasket three-layer shows sealing performance improvement that leakage did not occur in low axial force 40 kN for all surface roughness test. In terms of sealing, a three-layer gasket with a low thickness ratio works well. Surface roughness of the flange has no influence on the three-layer gasket

Copper electroplating technique for development of HTS current leads bottom joints using MgB2 wires

Low resistance, helium leak tight, cryo-stable superconducting (SC) joints with sufficient strength to absorb thermo-mechanical stress are commonly used in large sized magnets, their feeders and current leads (CL). Among high temperature superconductor (HTS), cuprate oxide based tapes are the popular options for CL applications. Recently composite magnesium diboride (MgB2) wires with superconducting transition temperature of 39 K are getting wide attention for low field applications. Use of Monel as a sheath material in MgB2 wires poses a major challenge while fabricating SC joints due to its low wettability and flowability using PbSn alloy based solder material. To tackle this issue, we exploited Cu electroplating technique to ease fabrication of MgB2 – NbTi: Cu as well as HTS: Cu - MgB2 joints. The details of in-house electroplating technique developed to fabricate bottom joints of BSCCO-2223 based HTS CL using MgB2 wires are reported. To study the morphology of such Cu coated MgB2 wires microstructural investigation is performed using Scanning Electron Microscope with energy dispersive X-ray spectroscopy (SEM/EDX) analysis. Similar Cu plated MgB2 wires are used to fabricate bottom joints of a prototype HTS CL. The performance of joints is preliminary attempted in the HTS CL test experiment up to 1.5 kA at 20 K.

Experimental and numerical study on rapid inflation process of air-launched balloon

The rapid inflation process is the most important stage in the whole working process of rapid deployment of aerostat. However, it is difficult to reveal its mechanical mechanism by existing experimental and numerical methods and reasonably explain the damage and helium leakage during the inflation process. An air-launched balloon for rapid deployment was designed and manufactured, and the related ground steady inflation experiment was carried out in this work. Then, the rapid inflation process of the folded balloon was studied by using the Simplified Arbitrary Lagrangian- Eulerian (SALE) method. Here, the folded balloon model was obtained by the reverse folding method. The structure and flow field were described by Lagrangian elements, and the coupling between them was obtained by a contact algorithm. The numerical results were in good agreement with the experimental results. The numerical method in this work could obtain abundant information on the structure and flow field which couldn’t be obtained by the experimental method. The change law of structure and flow field was obtained and the failure mechanism in the destructive experiment was explained. The numerical method proposed in this work could provide a reference for the material selection, gas source selection and structure optimization of the rapid deployment aerostat system.

Determination of the partial and total pressures of the mixed gases in atomic vapor cells by optical absorption

We study the partial and total pressures of the mixed gases in a Rb vapor cell from its absorption spectrum under the influence of natural broadening, self-broadening, pressure broadening, the pressure shift, and Doppler broadening. A comprehensive model of the absorption coefficient on the Rb D2 line is developed, which takes into account the influence of multiple gas species. The importance of light intensity selection and frequency calibration to obtain accurate experimental results are discussed. Accurate abundances are deduced from the experimentally measured absorption spectra of vacuum cells and are used to optimize the abundance parameters in our model. We fit the experimentally measured absorption spectrum of a gas-filled cell to the optimized model and obtain a root mean square error better than 0.1%. The extracted partial pressures indicate that the mixture ratio agrees well with the designed value, while the total pressure has an increment of about 17% of its nominal value. We further estimate the amount of helium leakage in a cell to be 89.1 Torr for 6 months. Moreover, using a series of absorption spectra generated by our model as benchmarks, we evaluate the effectiveness of the commonly used single and double Lorentzian fitting models and give some suggestions for using the double Lorentzian model. This study provides a reference for designing the appropriate gas mixture for comagnetometer systems.

Performance testing of the liquid nitrogen cooled sorption cryopump for application in SST-1 Tokamak

SST-1 is a Superconducting Tokamak for a proposed plasma discharge of long duration. To have plasma discharges, ultra-high vacuum is maintained in the vacuum vessel of this plasma device before filling discharge gases [1]. To attain a targeted pressure of ∼2.0E-8 mbar in the vacuum vessel, the plasma-facing components are baked to a temperature of 250 °C and the SS vacuum vessel is baked around 150 °C to remove impurities adsorbed/absorbed, from the bulk of the materials [2]. During baking, mainly the gas load of water vapour is increased significantly. Therefore, to cater the need of pumping speed of water vapour during baking, a customized liquid nitrogen based sorption pump was designed [3] and fabricated for the installation on the radial port of the machine. In this report, the performance testing of the pump will be discussed for the helium leak test, operating temperature test, pressure test, pumping speed test for water vapour and the regeneration process of the pumped gases. This paper also describes the assembly of the pump and the pumping speed of the gases up to the temperature around 150 °C, which is close to the baking conditions of the vacuum vessel of the SST-1. The pump demonstrates a pumping speed of ∼ 26,000 l/s for water vapour at a dosing rate of ∼ 2.6E-2 mbar-l/s at room temperature.

Influence of Porosity on Ultra-High Vacuum Gas-Tightness in Cold-Sprayed Aluminum Coatings

Vacuum chambers used in high-energy particle accelerator experiments are conventionally made of bulk beryllium, which shows significant drawbacks due to cost and toxicity. An alternative solution could be to develop chambers made of polymer-based composites. Since these materials exhibit high outgassing not compatible with an ultra-high vacuum environment, a suitable gas-tight coating is required. Cold spray deposition of aluminum can be a solution, provided that the coating behaves as a perfect vacuum barrier. Porosity, especially percolating porous networks, is key to coating gas tightness issues. This work addresses the relationship between porosity and gas-tightness in cold spray coatings. To do so, coatings with different porosity were achieved playing with powder morphology, composition, and process parameters. Their gas tightness was evaluated by helium leak tests. Classical microscopy, being essentially a 2D analysis, is strongly limited when dealing with 3D properties as porosity percolation. For this reason, 3D X-ray microtomography images of coatings were obtained and treated by image analysis methods: pores were compared in terms of size and shape. Overall porosity properties, including percolation and a homogeneity criterion, were also investigated. Percolating porosity was highlighted for several samples which showed poor gas-tightness properties. The permeability of percolating pore structures was then numerically computed by a fast Fourier transform-based method, to quantify the mass flow through the coating. Results of those computations were finally compared to experimental coating leak rate measurements, in an effort to elucidate the link between gas tightness and morphology of the pore space.

Leak-tight crack repair for 304L stainless steel using friction surfacing

Friction surfacing (FS) was investigated as a method for sealing 50 μm wide thru-cracks in 3-mm-thick 304L stainless steel (304L) plate. Friction surfacing was performed using two sizes of 304L consumable rod, with diameters of 9.52 mm and 12.7 mm, on two substrate conditions (clean and oxidized). Friction surfacing was able to deposit a 600 μm thick coating and repair cracks to a depth of 100 μm - 200 μm below the original surface, when using the 12.7-mm-diameter consumable rod for both substrate conditions. Helium leak rates of 10−10 atm-cc/s were achieved on crack repairs, designating them as leak-tight by the ANSI N14.5 standard. Optical and scanning electron microscopy were used to investigate the coating microstructure and bond interfaces. In this study, the 12.7-mm-diameter rod performed better with disruption of the oxide layer on the oxidized substrate and providing a more homogenous coating. Mechanical properties of the coated samples were evaluated by performing micro-indentation, tensile, bending, and adhesion testing. Higher hardness in the coatings was observed due to the fine equiaxed grains resulting from dynamic recrystallization. Complete consolidation of plastically deformed material on the substrate and a strong diffusion bond across the interface was observed. This was reflected in tensile and bending properties of the FS coatings being comparable to those of uncoated specimen. No delamination of the FS coating was observed during adhesion testing. The results demonstrate that friction surfacing is a viable option to seal cracks in stainless steels.

Containment Integrity and Sealing Assessment for HTR-PM600 Fresh Fuel Transport Package Under Impact Loading

Reliable transportation of fuel elements is vital for High Temperature Reactor (HTR) power plant. Therefore, the safety performance of the containment boundary in HTR-PM600 fresh fuel transport package under impact loading should be assessed. Specifically, factors such as the structural integrity, bolt safety, and sealing performance of the flange are considered. However, it is not convenient to assess the sealing performance using the helium leakage test without a prototypical experiment. Therefore, to accurately assess the safety performance in the design stage, we propose a detection technique combing with the finite element method to measure the leak channel in the flange for HTR-PM600 transport package. The results show that the boundary containment has no failure, and there is no complete leak channel in the flange of HTR-PM600 package. Hence, this package has a great safety performance under impact loading. This work also provides references for design of fresh fuel transport packages in pebble-bed reactors.

Fabrication and performance examination on explosively welded ODS-Cu / 316 L clad plate for CFETR divertor heat sink

Copper alloys are among the most promising candidate materials for divertor heat sinks owing to their remarkable advantages. However, it is challenging to use CuCrZr alloys as heat sink materials because of the harsh loading environment expected for plasma-facing components (PFCs) in future fusion reactors. Explosive welding is an effective method for manufacturing high-quality oxide dispersion strengthened copper (ODS-Cu) / 316 L stainless steel (SS) clad plates. Non-destructive testing results revealed a soundness bonding interface between ODS-Cu and 316 L without any detectable defects or cracks. In this study, optical microscopy and scanning electron microscope analysis revealed that the bonding interface did not contain any cavities and a typical wave-bonding morphology was observed. Moreover, the tensile stress of the bonding interface was higher than that of the ODS-Cu parent metal, and there was an increment in hardness on both sides near the bonding interface. The helium leak testing results indicate that the welded ODS-Cu / 316 L exhibits soundness without deformation or leakage at cyclic room and high temperatures. The results prove that the explosive welding method is a practical method for manufacturing high-quality ODS-Cu / 316 L clad plate that meet the design requirements and can provide critical references for the engineering design of the China Fusion Engineering Test Reactor (CFETR) divertor heat sink.

Assembly and interconnection technology for high-temperature bulk acoustic wave resonators

Abstract. A sensor based on a piezoelectric single crystal enables operation even under harsh environmental conditions. In addition to the sensor element, the packaging technology is crucial for sensor performance. In this paper, a suitable assembly and interconnection technology concept of Ca3TaGa3Si2O14 (CTGS) resonators for high-temperature applications is presented as a platform for future sensor assemblies. The concept described here has already been functionally tested as a temperature sensor (Schulz et al., 2021). The concept includes a sapphire base plate, a housing lid, and a spacer made from aluminium oxide (Al2O3). The substrate is metallised with platinum manufactured into thin film and thick film technology. The ceramic components are fused with glass solder. The connection of the resonator to the conductive tracks is realised by thermosonic bonding with 25 µm platinum wire. Initially, the stability of the metallisation must be investigated before subsequent electrical testing under high temperature. Diffusion processes play a major role in this temperature range, and the stability of the layer is a necessary condition for subsequent investigations. A suitable set of bonding parameters and the strength of the platinum bonds prior to and after thermal load is analysed. Shear tests are used to evaluate the quality of the ceramic materials fused with glass solder after thermal ageing. The dielectrical properties of sapphire and glass solder such as the isolation resistance, the relative permittivity, and the loss factor at high temperatures are evaluated using interdigital structures. The loss factor is measured on both bare interdigital structures and the samples coated with glass solder to make an estimation about the conductive behaviour up to 1000 ∘C. A ceramic lid for the sensor housing is attached by a high-temperature stable glass solder. Since platinum conductors are fed through this glass solder connection, the electrical conductivity of the glass solder is characterised at high temperature. Furthermore, the hermeticity of the assemblies is verified by means of helium leakage tests. These investigations are the basis for the implementation of an assembly and interconnection technology that is suitable for reliable operation under extreme temperature conditions. The packaging technology also offers further possibilities for pressure or chemical sensors that can withstand high-temperature loads.

Air, Helium and Water Leakage in Rubber O-ring Seals with Application to Syringes

We study the leakage of fluids (liquids or gases) in syringes with glass barrel, steel plunger and rubber O-ring stopper. The leakrate depends on the interfacial surface roughness and on the viscoelastic properties of the rubber. Random surface roughness is produced by sandblasting the rubber O-rings. We present a very simple theory for gas flow which takes into account both the diffusive and ballistic flow. The theory shows that the interfacial fluid flow (leakage) channels are so narrow that the gas flow is mainly ballistic (the so called Knudsen limit). We compare the leakrate obtained using air and helium. For barrels filled with water we observe no leakage even if leakage occurs for gases. We interpret this as resulting from capillary (Laplace pressure or surface energy) effects.

Development of automated fumigation chamber for treatment of grapes with SO2 and CO2

AbstractThe export of grapes from one country to another is dependent on the grape's quality that should pass the strict phytosanitary requirements of the importing country. There is a requirement of fumigation of grapes with CO2 and SO2 at specified concentrations for a certain period besides the other pack‐house protocols and export standards. This study was focused to develop and establish an electronically controlled model fumigation chamber for the treatment of grapes in the grapes‐producing region. The gas injection and evacuation systems are electronically operated, and the fumigant concentration can be varied according to the requirement. Heaters of 2 kW are fitted inside the chamber to maintain the treatment temperature above 16°C for grapes fumigation. The fumigation chamber was found leak‐proof during pressurized helium leak testing. The CO2 and SO2 gas concentrations can be maintained between 600 and 60,000 ± 100 ppmv and 10 and 10,000 ± 2 ppmv, respectively, for 1–90 min (1% is equivalent to 10,000 ppmv). The fumigation of grapes with 6% CO2 for 30 min followed by fumigation with 1% SO2 for 30 min ensured 100% mortality of the adult fruit fly (Drosophilla melanogaster). This chamber may also be used for the fumigation treatment of other fruits, vegetables, nuts, and so on, as per the time and concentration of gases required for the 100% mortality of target pest. Nevertheless, the protocol for such treatments should be developed for other fruits, and the effect of the gases on the quality of the products should be studied.Practical ApplicationsThe developed automated fumigation chamber for treatment of grapes with CO2 and SO2 is an effective measure for disinfesting the grapes from invasive pests like Drosophilla suzukii, spiders, and so on. This would help in overcoming phytosanitary measures put in place by many grapes importing countries like New Zealand, Australia, and so on. These countries offer huge market potential for export of Indian grapes, and if the trade barriers are overcome, it would lead to earning huge foreign exchange. Furthermore, the developed automated fumigation chamber can be used as an integral part of horticultural pack houses both for domestic as well as international trade as it would eliminate most of the adult field pests at preliminary stages before pack‐house operation.

Sealing behaviour of glass-based composites for oxygen transport membranes

In this study, seven different filler materials in different proportions were added to a Ba-Ca-Si glass matrix “H” to investigate new sealant with higher thermal expansion coefficient (CTE) value and good sealing performance for application in oxygen transport membrane (OTM). SrTi0.75Fe0.25O3-δ (STF25) was used as an OTM, and the sealing partners were ferritic steel Aluchrom and pre-oxidized Aluchrom. Compatibility tests were carried out to investigate the feasibility of the composites. Higher CTE values were found in dilatometer tests on composite samples by adding 40 wt% Ag (HAg40) and 30 wt% Ni-Cr (HNC30). Gas-tightness measurements of sandwiched samples produced appropriate helium leakage rates in the range of 10−6 mbar·l·s−1. Sealing behaviour of sealants HAg40 and HNC30 were investigated by joining STF25 and as-delivered/pre-oxidized Aluchrom together. Scanning electron microscopy (SEM) on cross-sections of the joints revealed a homogeneous microstructure and good adherence of the glass sealants to support metals and STF25.

Evaluation of the interfacial adhesion between polymer and metal on polymer-metal hybrids

Up to now there is no measuring method to quantify the interfacial adhesion between metal and polymer on hybrid parts. The present paper suggests a possible solution. With regard to interfacial tightness, the investigation on both a monolithic and a hybrid test specimen with a helium vacuum leakage measurement proved to be target-oriented for evaluating interfacial adhesion. The recording of the helium leakage rate over test duration enables the determination of a tight and thus well-adhering bond between polymer and metal. The results show that the previous consideration of absolute values instead of the time course of the leakage rate is not useful for determining a gap-free and thus tight interface, since gaps in the microscale result in a correspondingly low leakage rate. The determination of the leakage rate on both specimens allows the separation between measurand falsifying permeation rate and actual interfacial leakage rate. Therefore, gap-free interfaces from different material combinations can be compared regarding their true adhesion performance. On the other hand, microscopic studies of the interfacial zone as well as mechanical testing of the interfacial strength do not provide complete information on interfacial adhesion, micrographs especially can present interpretation confusing artefacts. The new developed and presented method will enable research into compatible material combinations, effective adhesion modifications and suitable processing conditions for improving interfacial adhesion between polymer and metal.

A Multicompany Survey Study for Helium Leak Container Closure Integrity Test.

All products labeled as sterile are required to be free of microbial contamination throughout their shelf life (obligatory critical quality attribute). Container closure integrity (CCI) needs to be addressed with a holistic life cycle strategy comprising adequate primary packaging components selection and the assessment of critical unit operations and critical process parameters (CPPs) according to quality by design (QbD) principles. The helium leak method is currently the most sensitive CCI test method and preferably used for the initial container closure system (CCS) qualification and characterization studies. Currently, two different measuring principles are used in the pharmaceutical industry, and no data is available in the public domain for typical method performance parameters such as accuracy, precision, intermediate-precision, and limit of quantification of the method. Furthermore, the performance of different types and sizes of artificial leaks as well as certified helium leak standards have not yet been characterized across different test laboratories. In this multicompany study, we shared 17 artificially prepared leak samples using the most common types of artificial leaks in relevant nominal size ranges that are commercially available or can be easily prepared in a laboratory. Each participating company generated results according to their in-house methods, applying their established test parameters as the aim of the study was not to create a standard for helium leak measurements, but to compare real-world performance between different laboratories. Consequently, this study is not an interlaboratory study using the same test method across laboratories.

RAMM-TM for detection of gas leakage from canisters containing spent nuclear fuel

Remote Area Modular Monitoring (RAMM) for canister surface temperature measurement (TM), or RAMM-TM, is a novel remote monitoring device for detection of gas leakage based on surface temperature measurements of canisters containing spent nuclear fuel. Development of RAMM-TM is described in this paper, as is the demonstration of its performance in detecting canister gas leakage from a small, simulated chloride-induced stress corrosion crack in experiments using a 1/4.5-scale model cask. Both helium and air gas leakage from a canister were detected within hours after the start of the leakage. The change in surface temperatures at the top and bottom of the canister (ΔTBT) during gas leakage (depressurization) triggered automatic alarms, providing a sound basis for early detection of gas leakage from the canister. This methodology would allow consequence management through the implementation of mitigatory actions to continue effective aging management and to reduce risks to public safety, health, and the environment.

New Method of Leak Rate Measurement in SF6 Free Medium Voltage Switchgear Using Helium and Ambient Air

Abstract The current medium voltage Gas Insulated Switchgears (GIS) predominantly use Sulphur Hexafluoride (SF6) as insulation medium. The leakage tests performed on GIS use either SF6 or Helium medium to ensure gas tightness. However, SF6 has been strictly regulated for the last years due to the high global warming potential effect on the planet. As a response, new technologies are emerging using air as insulation medium. The present work establishes a basic comparison of the leakage rate in a medium voltage GIS using two different leak detection methods: Helium leak detector and Residual Gas Analyser (RGA). Both methods use Helium and additionally RGA using air as tracer gas.