Leak Testing System Research Articles

Air leakage test system for product without atmosphere air connection

With the air leakage test methods, the leakage tests of the products that are required to be leakproof are carried out. This leakage test starts with placing the product on a fixture. The in-ternal pressure is increased by filling compressed air into the product placed in the Fixture. The product is filled with compressed air up to a previously calculated test pressure value. After the test pressure value is reached for the desired product, the air filling process is completed, and the stabilization period begins. At the end of this period, information about the leakage of the product is obtained, depending on whether there is a change in the internal pressure of the product. In order to fill the product with compressed air, there must be an air hole on the product. Products without this air hole cannot be tested with these methods. With the new method we will develop, it will be possible to test the leakage of closed products without atmosphere-air connection.

A Three-Factor Accelerated Aging Test Platform of Thermal, Mechanical Compression, Pressured SF6, and a Leakage Test System for GIS O-Ring Seals

The multifactor accelerated aging test is an important means to predict the lifetime of gas-insulated switchgear (GIS) O-ring seals, while the leakage rate (LR) is a potential index for failure evaluation. This article proposed a three-factor accelerated aging test platform and a leakage test system (LTS) for GIS seal rings. The aging factors are thermal, mechanical compression, and pressured SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> gas. The pressure aging vessel (PAV) can be filled with various gases to simulate the operating conditions of the GIS and age multiple samples simultaneously. During the aging process, leakage tests are conducted on flange pairs without disassembling and separating the seal rings. After the test, the aging can be continued so as to study the evolution of LR with aging time. In order to analyze the properties of leakage test and validate the platform, a three-factor accelerated aging and a traditional two-factor accelerated aging (thermal and compression) were conducted on GIS O-ring seals of EPDM material. Compression set (CS) and LR were tested. The result showed that a steady inherent LR F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> exists for the LTS. The LR rose linearly with accumulating time, allowing simplified calculation of LR. The three-factor aged samples had significantly smaller CS than those of the two-factor aged samples, indicating that the working condition of GIS with SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> atmosphere significantly slows the aging rate of GIS seal rings. The findings proved that the three-factor accelerated aging test platform and LTS effectively simulate the operating conditions of GIS seal rings and evaluate their properties.

Development of leakage test system of cartridge valve based on NI vision

In order to realize the leakage test of cartridge valve, an automatic test system based on machine vision is designed, and the working principle of the system is described. Through the analysis and processing of the leakage image obtained by industrial camera, the leakage flow of the valve are obtained to determine whether they meet the national standards. Finally, the feasibility of the test system is verified by theoretical analysis and experiment.

Effect of Nd: YAG laser on the apical seal after root-end resection and MTA retrofill: a bacterial leakage study

Laser irradiation has been investigated in terms of preventing leakage in retrofilled root canals. The aim of the present study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the bacterial leakage of mineral trioxide aggregate (MTA)-retrofilled roots. In this ex vivo experimental study, 90 single-rooted incisor teeth were filled with gutta-percha and AH26 sealer. The apical 3mm of all the roots were resected and 3-mm retrocavities were prepared by an ultrasonic device. The specimens were randomly divided into two experimental (n = 25), one positive control (n = 10), and two negative control (n = 10) groups. In the laser + MTA group, the cavity walls were irradiated by Nd: YAG laser prior to MTA placement. In the MTA group, MTA was placed without laser irradiation. The root surfaces were covered with two layers of nail varnish except for the apical 2mm. The specimens were then embedded in a bacterial leakage test system and examined daily for 90days. Contamination periods were recorded. Data were analyzed by Kaplan-Meier and Mann-Whitney U tests (α = 0.05). Five teeth with and five teeth without laser irradiation underwent scanning electron microscopic evaluation. The specimens in the laser + MTA group were contaminated earlier than those in the MTA group (p < 0.05). Comparison of survival times between the two groups showed significant differences (p < 0.05). Nd: YAG laser irradiation can decrease the sealing capacity of MTA in comparison to the apical seal achieved by MTA without laser irradiation. Further studies are recommended to provide a better seal for the MTA-retrofilled teeth after laser irradiation.

Leakage research on supercritical carbon dioxide fluid in rolling piston expander

The leakage research on supercritical carbon dioxide fluid in rolling piston expander was investigated experimentally. Using expander instead of throttle valve is an important way to improve the efficiency of carbon dioxide refrigeration system. However, the supercritical fluid leakage in expander is serious and is the main factor affecting the expander’s efficiency. This paper presented and compared four classic leakage models. The analysis indicated that laminar leakage model is suitable in leakage simulation of expander. A leakage test system, including the leakage test part which has two types of leakage specimens with different gaps ranging from 5 to 15 μm, was established. The experimental results indicated that lubricant film played an important role. When the leakage clearance of cylindrical specimen was 5 μm, the mass flow rate of leakage was about 0.88 g s−1. The data was 3.638 g s−1 with leakage clearance being 10 μm and 7.11g s−1 with leakage clearance being 15 μm. A modified leakage model was developed, whose average deviation was within 10% compared with the experimental data. At last, this paper simulated the leakage in rolling piston expander presented by Tian et al. (2010). The leakage between rolling piston and cylinder was the most serious part with the value up to 0.04 kg s−1.

Development of Helium Leak Testing System and Procedure for testing Welds of Steam Generator

Abstract The main function of Steam Generator (SG) in FBR is to extract the reactor heat through secondary sodium system and convert the feed water into superheated steam in the tubes of SG. The Steam Generator is a vertical, once through, shell and tube type heat exchanger with liquid sodium in the shell side and water/steam in the tube side. The highly reactive nature of sodium with water/steam requires that the sodium to water/steam boundaries of the steam generators mus t possess a high degree of reliability against failure. This paper highlights the experiences in helium leak-testing in vacuum mode to detect a leak rate of the order 6.66 X 10-9 Pa.m3/s, as specified.

Evaluation of the burst characteristics for axial notches on SG tubings

Some events of steam generator tubes have been reported in some nuclear power plants around the world. Main causes of the leakage are from various types of corrosion in the steam generator (SG) tubing. Primary water stress corrosion cracking (PWSCC) of steam generator tubing have occurred in many tubes in Korean plants, and they were repaired using sleeves or plugs. In order to develop proper repair criteria, it is necessary to ascertain the leak behavior of the tubings. A high-pressure leak and burst testing system was manufactured. Various types of electro-discharged-machined (EDM) notches having different lengths were machined on the o.d. of test tubes to study SG tube behavior. Leak rate and ligament rupture pressure as well as the burst pressure were measured for the tubes at room temperature. Rupture pressure of the part through-wall defect tubes depends on the defect depth and length. Water flow rates after the rupture were independent of the flaw types; tubes having 20–60 mm long EDM notches showed similar flow rates regardless of the initial defect depth. A fast pressurization rate generated a lower burst pressure than the case of a slow pressurization.

The NTL Leak Testing System for Fuel Transport Flasks

AbstractThe NTL Leak Testing System for Fuel Transpon Flasks has been developed to ensure the integrity of the lid sealing system used on NTL's fleet of ‘wet’ fuel transpon flasks prior to shipment. The flask lids are sealed using two concentric elastomer O-rings. The performance of the seals is tested by pressurising the space between the seals to approximately 7 bar (gauge) and observing the pressure change with time. Historically, the test has been performed using a Bourdon gauge, however this presents two problems: (1) The insensitivity of the gauge results in long test times. (2) The flasks are loaded with hot fuel. This results in gas pressure rises as the temperature of the flask increases following fuel loading. To overcome these problems, a system has been developed which uses a water manometer to measure the pressure drop. The system is fully compensated for the post loading temperature changes, and offers a substantial increase in sensitivity when compared to the Bourdon gauge. The problems ass...

New applications of the computerized multiprobe flux leakage test system STAR

New applications of the computerized multiprobe flux leakage test system STAR

Cryogenic leak testing of tube fittings/valves

A high pressure and variable temperature cryogenic leak testing system was conceived and designed in order to conduct leakage testing of pipe fittings/valves in liquid hydrogen supply lines of the space shuttle. The system can create a continuous testing environment of variable temperature, 5.5 K ∼ 300 K, and variable pressure, 10 −2 Pa ∼ 70 × 10 5 Pa, with a large sample space, 90 mm diameter × 228 mm length, and at low operating cost. In terms of cryogenic leak testing the system has a special capability for extensive applications. The system comprised a variable temperature cryostat, a high pressure sample chamber, a vacuum pumping station, gas flow control system, pressure and temperature control systems, and leak detecting and measuring systems. A general discussion of cryogenic leak testing methods is also presented.

New applications of the computerized multiprobe flux leakage test system STAR: 36895 Huschelrath, G.; Schneider, P. Proceedings of the 9th Congress of Materials Testing, Budapest (Hungary), 29 Sep. – 3 Oct. 1986. Vol. 2. pp. 616–617. Edited by E. Czoboly. Scientific Society of Mechanical Engineers (1986)

New applications of the computerized multiprobe flux leakage test system STAR: 36895 Huschelrath, G.; Schneider, P. Proceedings of the 9th Congress of Materials Testing, Budapest (Hungary), 29 Sep. – 3 Oct. 1986. Vol. 2. pp. 616–617. Edited by E. Czoboly. Scientific Society of Mechanical Engineers (1986)

Screening and characterization of membrane damaging effects in tissue culture

A leakage test system for specific detection, measurement and characterization of membrane damage in human lung fibroblasts is discussed. Examples of applications with various types of substances are presented, i.e. tobacco smoke compounds; animal, plant and microbial cytolysins; membrane damaging antibiotics.

Introduction of leak-testing method and system for cans of rod-type fuel elements of reactor of first block at the Beloyarsk Atomic Power Plant

Introduction of leak-testing method and system for cans of rod-type fuel elements of reactor of first block at the Beloyarsk Atomic Power Plant

Abstract: Leak testing large vacuum systems

Testing of large vacuum systems for leaks may best be described as a problem in high vacuum engineering with leak detection methods as a tool for its accomplishment. Before any leak testing is performed, it is necessary to determine the operating limits for the vacuum system which in turn are used as the boundary conditions for specification of acceptable leak rates. After determination of the leak rates which are acceptable to the overall vacuum system operation, a leak testing system design and procedure is developed to satisfy the leakage criteria. The leak testing philosphy to be followed is little different than any other leak testing problem.Differences found in leak testing of large vacuum systems as compared to laboratory systems are primarily ones of physical magnitude and emphasis. For example, the roughing cycle commonly used on small components, i.e., laboratory vacuum systems and components of less than 50 ft 3 volume, is of little concern when making use of a mass spectrometer leak detector ...

New Automatic Leak Testing System with Helium Mass Spectrometer Leak Detector

To improve production leak testing of components of air conditioner, automobile, etc., new automatic systems with helium mass spectrometer leak detector were developed. Design basis and performances of typical two systems for automatic leak testing based on hood method and reverse hood method are described. In addition, reliability and durability of vacuum components for high speed operation of the system and the clean-up time of helium leak detector are discussed. A full automated leak testing system makes possible by adding sub-systems such as devices of loading, unloading, selecting good or leaky components, to the automated reverse hood method's system. Summarized performances of two systems are as follows : A) Automatic hood method's leak testing system.1. Detectable leak rate in working condition : About 1×10-6 Torr l/sec if the work volume is about 1 liter.About 2×10-6 Torr l/sec if the work volume is about 2 liter.2. Detectable sensitivity including all system : About 6×10-9 Torr l/sec/div. if the work volume is about 1 liter.About 1.3×10-8 Torr l/sec/div. if the work volume is about 2 liter.3. Operation speed : 2530 seconds per each one.4. Helium comsumption : 7m3 monthly, 7hr operation/day, 22 working days/month.B) Automatic reverse hood method's leak testing system.1. Detectable leak rate in working condition : About 1×10-6 Torr l/sec if the chamber volume is about 100 liter and the operating speed is 20 seconds per each one.2. Detectable sensitivity including all system : About 8.5×10-9 Torr l/sec/div. if the chamber volume is about 100 liter and the operating speed is 20 seconds per each one.