Pinhole leaks

Rupture discs are also used below relief valves to protect them from corrosion due to ves.sel fluids. The rupture disc bursts first and the relief valve immediately opens. The relief valve reseals, limiting flow when the pressure declines. When this configuration is used, it is necessary to monitor the pressure in the space between the rupture disk and the relief valve, either with a pressure indicator or a high pressure switch. Othei-wise, if a pinhole leak develops in the rupture disk, the pressure would equalize on both sides, and the rupture disk would not rupture at its set pressure because it works on differential pressure. 

What are potential consequences if a pinhole leak develops in a tube in the... 

If there is a large pinhole leak a few inches below tlie liquid surface, it will behave like a leak above the liquid. How ever, a small pinhole leak in the same location may have zero inleakage due to capillary effects. The problem becomes complicated as the depth becomes large, and... 

In the long term (20-40 years), the overall domestic HW system is subject to pinhole leaks stemming from the galvanic corrosion of steel riser pipes (usually located in inaccessible areas), with resultant flooding within the building. Galvanic corrosion develops because these systems typically contain a wide range of mixed metals such as black... 

Instrumentation exists that reveals pinhole leaks or cracks by detecting a tracer gas which escapes when the package is placed in a partial vacuum [11], In addition to their normal contents, therefore, packages to be tested must contain an easily identifiable tracer gas. It is desirable that this gas be inexpensive, nontoxic, inert, and easy to detect. Carbon dioxide (C02) is one gas that meets these general requirements. 

When using a rupture disc followed by a spring-operated relief, it is important to periodically check the pressure gauge to be sure that there is no pinhole leak in the rupture disc. Describe several methods to satisfy this requirement. 

General corrosion in the top 5 -inch region of the upper liner after the 500-hour test was also observed. This relatively uniform corrosion is estimated to penetrate the 0.15-inch-thick liner to about 0.008 inch. Had it not been for the pinhole leaks, the liner would have had significant remaining service life. However, Foster Wheeler concluded that the test did indicate the upper... 

Moderate (3 weeks) Pinhole leak floor tube Faulty weld on membrane bar between floor tubes, made 10-15 yr earlier... 

The initial incident involved a pinhole leak on a 6-in. line located 112 feet above grade. The unit might have been shut down at this point, but a decision was made to keep it on line. Efforts to isolate the circuit by closing four block valves failed. The line remained hot and the level in the downstream stripper vessel continued to rise. Several attempts were made to depressure the circuit and free drain all the residual naphtha. At least 15 work orders were issued over a 13-day period and most of these failed to meet the company s own work standards. 

To demonstrate that HEPA filters are properly installed by verifying the absence of bypass leakage and other defects such as tears and pinhole leaks... 

Recently, Kohout and Lampe264 decomposed H2 or D2 by mercury sensitization in the presence of NO. The experiments were done in a cell with a pinhole leak to a Bendix time-of-flight mass spectrometer. They directly observed mass spectral peaks at m/e = 31 or 32, which correspond to HNO or DNO, respectively. 

Lossing, Ingold, and Tickner287 slowly flowed mixtures of ethylene oxide and nitric oxide, in a He diluent, into a heated quartz tube with a pinhole leak to a mass spectrometer. They measured the decrease, resulting from the addition of NO, in both CH4 and CH3. In this way, they could follow the competition between reaction (7) and... 

The experiments of Kistiakowsky and Kydd [1] were done by single-pulse photolysis with a 500-J flashlamp, the reaction vessel contents being sampled via a pinhole leak into the electron ionization source of a Bendix time-of-flight (TOF) mass spectrometer. Mass spectra were obtained by pulsed extraction of ions from the ion source at 50-fis intervals after the flash. The signal from the electron multiplier detector was displayed on a cathode ray tube, which was photographed with a rotating drum camera. 

Generators. When placed in service, two units developed leaks at the header tube connections which had not appeared under test. These were welded in place. One tube developed a pinhole leak. This was cut out and replaced by a new tube. 

The success of the analysis in correlating experimental data for clean filters offers convincing support for the theory of convective diffusion of particles of finite diameter to surfaces. As particles accumulate in the filter, both the efficiency of removal and the pressure drop increase, and the analysis no longer holds. Some data on this effect are available in the literature. Care must be taken in the practical application of these results because of pinhole leaks in the filters or leaks iU ound the frames. 

In our laboratory a microwave discharge was generated in helium by a 100 watt Raytheon microtherm generator and sampled through a pinhole leak at the apex of a conical probe into a quadrupole mass filter. Typical variations in the intensities of He+ and He2+ with pressure are given in Figure 1. If the He2+ is formed by the three-body process (Equation 11) the rate constant would have to be about 10"28 cc.2/mole-cule2/sec. which far exceeds the measured value (84). We conclude then that the diatomic ion is formed principally by the chemi-ionization process (Equation 10). 

The exception to the rule IMS must be interfaced to MSs through a pinhole leak is when they are interfaced to some type of ion-trapping MS. Because ion traps collect ions for several seconds, IMS mobility resolution is lost. Thus, ion traps such as Paul traps, linear traps, Orbitraps, and FTICR instruments require a mobility-filtering type of IMS. When drift tube IMS instruments are interfaced to trapping MSs, a two ion gate system must be employed to select specific mobilities to trap in the MS. 

As expected from Graham s law, helium escapes from containers through tiny pinhole leaks more rapidly than other gases of higher molecular weight ( FIGURE 10.20). 

Suppose you have two 1 -L flasks, one containing N2 at STP, the other containing CH4 at STP. How do these systems compare with respect to (a) number of molecules, (b) density, (c) average kinetic energy of the molecules, (d) rate of effusion through a pinhole leak ... 

---