Leak measurements

Figure 5 Leak measurement for each load level...

Figure 7.34. Allometric relationship of mitochondrial proton leak and body mass. Proton leak measured at a potential of 170 mV is expressed per unit volume (ji ) of mitochondrial matrix. Numbers refer to the following species (1) mouse, (2) hamster, (3) rat, (4) ferret, (5) Dutch rabbit, (6) New Zealand rabbit, (7) sheep, (8) pig, and (9) horse. (Figure modified after Porter et al. 1996.)...

Nguyen, L.T. Muangsiri, W. Schiere, R. Guazzo, D.M. Kirsch, L.E. Pharmaceutical container/closure integrity IV development of an indirect correlation between vacuum decay leak measurement and microbial ingress, PDA. J. Pharm. Sci. Technol. 1999, 53, 211-218. 

Helium leak tests were carried out under load pressure up to 4 MPa and surface temperature of the models up to 500°C. All cormections were installed in a vacuum electric furnace, and leak rates were measured with a helium leak detector. Table 2 shows the leak rates obtained at 500°C in the third times at the heat cycle up to 5()()°C, and Table 3 obtained under 2()°C after the leak measurement at 500°C shown in Table 2. In these tables, line loads and seating stresses (tightening forces) are also indicated. As seen these tables, although the tightening forces under 500°C decreased down to less than... 

Leak measured relative to the specifications BWRs PWRs... 

Samples for measurement were parallelepipeds (5 x 5 x 30 mm). Results are listed in Table IV and shown in Fig. 1. They were obtained with the double flux method, which permits the elimination of first order systematic errors owing to the parasitic heat leak. Measurements below 7 K were taken with superconducting heating leads to reduce the heat leak. The temperature difference was measured with a gold/iron - Chromel thermocouple, xsrhich constitutes a thermal shunt. This must be taken into account to calculate the sample thermal conductivity. At values near 10 W/cm K at 2 K, for instance, the calculated correction amounts to nearly 30%. 

Spanish NPPs with extensive degradation phenomena in the steam generators have in operation a detection system, based on the monitoring of the short-lived N-16, installed in the steam lines. This system has been introduced into the Technical Specifications. The previous method of leak measurements, based on the monitoring of the steam generators blowdown, is used to confirm the N-16 readings. 

In electron spin echo relaxation studies, the two-pulse echo amplitude, as a fiinction of tire pulse separation time T, gives a measure of the phase memory relaxation time from which can be extracted if Jj-effects are taken into consideration. Problems may arise from spectral diflfrision due to incomplete excitation of the EPR spectrum. In this case some of the transverse magnetization may leak into adjacent parts of the spectrum that have not been excited by the MW pulses. Spectral diflfrision effects can be suppressed by using the Carr-Purcell-Meiboom-Gill pulse sequence, which is also well known in NMR. The experiment involves using a sequence of n-pulses separated by 2r and can be denoted as [7i/2-(x-7i-T-echo) J. A series of echoes separated by lx is generated and the decay in their amplitudes is characterized by Ty. ... 

All calorimeters consist of the calorimeter proper and its surround. This surround, which may be a jacket or a batii, is used to control tlie temperature of the calorimeter and the rate of heat leak to the environment. For temperatures not too far removed from room temperature, the jacket or bath usually contains a stirred liquid at a controlled temperature. For measurements at extreme temperatures, the jacket usually consists of a metal block containing a heater to control the temperature. With non-isothemial calorimeters (calorimeters where the temperature either increases or decreases as the reaction proceeds), if the jacket is kept at a constant temperature there will be some heat leak to the jacket when the temperature of the calorimeter changes. 

Hence, it is necessary to correct the temperature change observed to the value it would have been if there was no leak. This is achieved by measuring the temperature of the calorimeter for a time period both before and after the process and applying Newton s law of cooling. This correction can be reduced by using the teclmique of adiabatic calorimetry, where the temperature of the jacket is kept at the same temperature as the calorimeter as a temperature change occurs. This teclmique requires more elaborate temperature control and it is prunarily used in accurate heat capacity measurements at low temperatures. 

In practice the laser can operate only when n, in Equation (9.2), takes values such that the corresponding resonant frequency v lies within the line width of the transition between the two energy levels involved. If the active medium is a gas this line width may be the Doppler line width (see Section 2.3.2). Figure 9.3 shows a case where there are twelve axial modes within the Doppler profile. The number of modes in the actual laser beam depends on how much radiation is allowed to leak out of the cavity. In the example in Figure 9.3 the output level has been adjusted so that the so-called threshold condition allows six axial modes in the beam. The gain, or the degree of amplification, achieved in the laser is a measure of the intensity. 

In applying the definition of rehabihty, the concept of adequate performance must be estabhshed clearly. Products usually do not fail suddenly, but degrade over time. Gasket leaks on equipment, for example, may start as a slow weep and increase in volume over time. The point at which this undesirable occurrence is called a failure must be clear before rehabihty can be measured objectively. Changing the failure definition for a product changes its rehabihty level, although the product itself has not changed. 

Leak or spill source Characteristics Root causes Preventive measures... 

Precision mass and volumetric methods use very precise measurements of pressure and/or level in the tank to detect leaks. The tank must be closed so that no Hquid enters or leaves the tank. The threshold of detection and fuimel required to perform a rehable test become greater as tank size increases. 

Detecting Leaks Small leaks are difficult to detect. The USEPA and American Petroleum Institute standard for nonlealdng underground tanks is 0.05 gaUh (3.15 cmVmin), above which a tank is considered to be leaking. Leak detection measurements can be influenced by many factors, making it difficult to detect small leaks. 

Systematic Operating Errors Fifth, systematic operating errors may be unknown at the time of measurements. Wriile not intended as part of daily operations, leaky or open valves frequently result in bypasses, leaks, and alternative feeds that will add hidden bias. Consequently, constraints assumed to hold and used to reconcile the data, identify systematic errors, estimate parameters, and build models are in error. The constraint bias propagates to the resultant models. 

P IDs (piping and instrumentation diagrams) should identify instruments, sample locations, the presence of sample valves, nozzle blinding, and control points. Of particular importance are the bypasses and alternate feed locations. The isolation valves in these hues may leak and can distort the interpretation of the measurements. 

However, given that reconciliation will not always adjust measurements, even when they contain large random and gross error, the adjustments will not necessarily indicate that gross error is present. Further, the constraints may also be incorrect due to simphfications, leaks, and so on. Therefore, for specific model development, scrutiny of the individual measurement adjustments coupled with reconciliation and model building should be used to isolate gross errors. 

---