Leak Detection Device Research Articles

Minimum Leak Size Determination, under Laboratory and Commercial Conditions, for Bacterial Entry into Polymeric Trays Used for Shelf-Stable Food Packaging

This study sought to determine the minimum leak size for entry of Enterobacter aerogenes under laboratory conditions, and normal flora under commercial conditions, into tryptic soy broth with yeast extract (TSBYE), homestyle chicken, and beef enchilada packaged in 355-ml polyethylene terephthalate/ethylene vinyl alcohol/polypropylene trays. Channel leaks (diameters of 50 to 200 μm) were made across the sealing area of the trays. Pinholes (diameters of 5 to 50 μm) were made by imbedding laser-drilled metal and plastic disks into the tray lids. For the laboratory simulation, all trays were submerged and agitated for 30 min at 25°C in phosphate-buffered saline that contained 107 CFU/ml of E. aerogenes. Under commercial conditions, trays with channel leaks were processed in retorts to achieve commercial sterility. All trays were subsequently incubated at 37°C for 2 weeks, and their contents plated onto eosin-methylene blue agar (for laboratory simulation) to enumerate E. aerogenes and brain heart infusion agar (for commercial conditions) to determine the presence of any bacteria. Under laboratory conditions, minimum pinhole sizes for E. aerogenes entry approximated 5μm (TSBYE, metal disks; homestyle chicken, plastic disks), 20μm (beef, plastic disks), and 30μm (beef, metal disks). The minimum channel leak sizes for entry of E. aerogenes approximated 10μm (TSBYE), 70μm (chicken), and 200μm (beef enchilada). Under commercial conditions, the minimum channel leak size for bacterial entry approximated 40μm (TSBYE), 50μm (homestyle chicken), and more than 200μm (beef). Results showed that E. aerogenes can enter pinholes as small as 5μm under a worst-case scenario. This information can be used to set pass and fail parameters for leak detection devices.

Surmounting design problems in a complex piping system for groundwater remediation

AbstractThis paper describes the design of a fiberglass reinforced plastic (FRP) piping system which transports groundwater extracted from 43 wells at the site of a former chemical manufacturing plant in Toms River, New Jersey. This system conveys an average flow of 2.7 million gallons per day of groundwater contaminated with aromatics, chlorinated hydrocarbons and metals through seven miles of pipeline to a biological and physical treatment plant. The piping system, shown in Figure 1 exceeds the scale typically seen in most groundwater remediation projects, with respect to length, number of wells and volume of water treated.The groundwater extraction system is a manifold piping network that consists of the 43 wells and associated pumps, piping and controls and is capable of conveying 150% of the average flow. All piping within plant boundaries is above ground. Offsite piping is installed below ground and is double walled. Leak detection devices are installed below ground in manways along the buried pipe route. Discharge piping from well pumps is tied into manifolds which go to the groundwater treatment plant.This paper describes design choices significantly affecting the system construction, piping system components, design procedures and significant lessons learned in the construction of the system. System design commenced in 1993, was completed in 1995 and system construction was finished in 1996.

Examination of processes for multiple contaminant removal from groundwater

This paper has reviewed six processes for nitrate and hardness removal for the City of Seward, Nebraska. Of these processes, ion exchange nitrate removal was shown to be the least expensive process to meet water quality regulations. However, brackish water reverse osmosis, at 12% higher cost, will not only meet the regulations, but provide an overall better water quality with substantial hardness reduction as compared to the existing water supply. It is therefore an attractive alternative. The study showed that the cost of waste disposal has a dramatic affect on the overall cost of a project. In fact, waste disposal consists of more than half of the capital cost of the ion exchange processes. This is because of the need to construct double lined evaporation ponds with leak detection devices for these processes. In other locations where a more economical waste disposal alternative exists, these costs could be substantially lowered. Again, at this location it was determined that wastes produced by membrane processes could safely be sent to the existing wastewater treatment plant. This substantially reduced the cost of waste disposal for these processes, making them more attractive. In other locations where this form of disposal is not available, substantially different disposal costs might be found. It becomes obvious that selection of the appropriate treatment process for a specific location requires careful evaluation of the capabilities and costs of the processes and of their waste handling requirements.

Protocol for selecting an in‐tank leak detection device

A protocol has been developed to rank in‐tank detection devices for underground storage tanks. Eleven leak detection devices were selected and evaluated relative to 12 decision factors. The importance of the factors differs with environmental, physical and economic conditions, therefore, four hypothetical operating situations were used for evaluation. The unranked paired‐comparison technique was used to weight the decision factors. The ranking approach for the in‐tank detection was devices simplified by a categorization scheme. The resultant decision matrix indicates that the selection of a leak detection device should be based upon the operating conditions and choices among devices that satisfy regulations and decrease the possibility of user liability.

History of helium leak detection

The first atomic bomb used uranium isotope 235, which occurs in nature together with uranium-238, from which it has to be separated. The separation was accomplished in 1944–1945 in a huge ‘‘diffusion’’ plant using microporous tubing as the diffusion medium. The process was such that moist ambient air could not be tolerated in the process chambers. Accordingly, all the equipment had to be ‘‘free’’ of leaks. Equipment of the size used in the diffusion plant had never been tested to such an extreme specification. A number of leak detection devices were tried and proved inadequate. Ultimately, a simplified mass spectrometer based on the Nier 60 in. spectrometer tube was chosen for leak detection. It could easily be set to detect helium which was the choice for ‘‘probe’’ gas. From an original sensitivity such that a flow of 10−6 std cm3 of helium could be detected, the current unit has been improved so as to detect a flow of 10−10–10−11 std cm3. Size of the detector has been reduced by almost an order of magnitude and operation is highly automated.

Development of a Standard, Pure‐Compound Base Gasoline Mixture for Use as a Reference in Field and Laboratory Experiments

AbstractIn recent years, leaking underground petroleum storage tanks have become a major environmental concern. Federal, state, and local agencies are making efforts to assess, control, and remediate petroleum product leaks. Because petroleum products are mixtures of many compounds and the composition frequently changes, there exists a need for a standard reference mixture that can be used as a basis for comparison in the study of fluid transport properties in porous media and to evaluate leak detection devices. The proposed standard presented here retains the most important liquid and vapor properties (such as vapor density, air diffusion coefficient, and basic chemical constituency) of gasoline mixtures. It also reduces the complexity of the mixture to make it an acceptable standard for routine use in laboratory and field experiments.

Leak-before-break in French nuclear power plants

Practical applications of the leak-before-break concept at the present stage are quite limited in French nuclear power plants. However, discussions with safety authorities have included leak-before-break arguments for the different types of reactors: pressurized water reactors (PWRs), liquid metal fast-breeder reactors (LMFBRs) and gas graphite reactors (GGRs). At present, the fracture mechanics part of the studies are complete for the following components: • —pipes in GGRs; • —primary and auxiliary lines in PWRs; • —steam-generator tubes in PWRs; • —pipes and main vessels in LMFBRs. The different approaches are consistent but some specific problems have to be taken into account, depending on the plant, such as creep regime, thin shell components, in-service inspection or the issue of design safety. A large research and development program, realized in different cooperative agreements (national or international), completes the general approaches. It comprises different topics, such as material properties, elastoplastic fracture mechanics, leak-area determination and leak-detection devices. Although practical applications are limited at present, EDF, in conjunction with Framatome, Novatome and CEA, will define a complete validated methodology to be used on a variety of cases.

Method and device for leak detection: Esso Research and Engineering Co French Patent 1, 568, 814 (2 May 1969) (Applied for 3 May 1968) (in UK 5 May 1967)

Method and device for leak detection: Esso Research and Engineering Co French Patent 1, 568, 814 (2 May 1969) (Applied for 3 May 1968) (in UK 5 May 1967)