Leak detectors, electronic

After making a connection, check for leaks by placing a few drops of ethanol, an electronic leak detector, or a high boiling polypropylene glycol solution around the joint. If bubbles appear, then a leak is present. Do not use a soap solution (phosphates) or other leak detectors (halogens). 

SOLID STATE HALOGEN LEAK DETECTOR - An electronic leak detector for all halogen, related refrigerants. 

Electronic leak detectors, which are capable of sensitivities far greater than the other methods-often in terms of fractions of an ounce of fluorocarbon per year. 

FIGURE 10.21 Leaks checking a valve with an electronic leak detector [reprinted with... 

Electronic leak detectors, which are capable of sensitivities far greater than the other methods—often in terms of fractions of an ounce of fluorocarbon per year. When the probe of the instrument is placed near a leak, positive identification of the leak is indicated by a flashing light, by meter deflection, or by audible means. 

National Dreager Inc., manufacturer of detector tubes and respiratory equipment, has developed two versions of the Model 80 facemask fit-test device using 2% by volume ethylene as the test gas. This method uses either a detector tube or an electronic leak detector to measure the concentration of test gas exhaled in the breath. With detector tubes, 0.5-10 ppm of ethylene leakage tests can be detected in the range of 0.0025 to 0.05%. 

In the use of an electronic leak detector method, a 2% mixture of sulfur hexafluoride in air is used as the test gas. Detector sensitivity is approximately the same as the detector mbe method of test. The presence of the radiation source in this detector, however, requires a special... 

The injection port septum is an unsolved weak point in GC. It is arguably the most important but often overlooked functional part of the injector. The septum is used to seal the injection port, and withstands the inlet pressure and provides smooth and repeated access for the syringe needle to inject the sample. The syringe needle punches the septum repeatedly in a small area causing only gradual small leaks, which are detectable with an electronic leak detector already before a noticeable analyte response drop occurs. The risk of leaks increases with use, older septa take longer to re-seal than new ones (Hinshaw, 2008). 

We could also refer to this as reduced sensitivity. The peaks are smaller than expected based on previous observations when equal or greater quantities of a particular sample were injected. Such an observation usually means a problem with injection (less injected than assumed) or a problem with the detector such that a smaller electronic signal is sent to the recorder. One should check for a leaky or plugged syringe, a worn septum, a leak in the pre- and postcolumn connections, or a contaminated detector. Of course,... 

Radon is present in the air and soil. It can leak into the indoor environment through dirt floors, cracks in walls and floors, drains, joints, and water seeping through walls. Radon can be measured by using charcoal containers, alpha-track detectors, and electronic monitors. Results of the measurement of radon decay products and the concentration of radon gas are reported as working levels (WL) and picocuries per liter (pCi/L), respectively. The continuous exposure level of 4 pCi/L or 0.02 WL has been used by USEPA and CDC as a guidance level for further testing and remedial action [33]. 

When the baseline varies randomly over times similar to the peak width, it is called wander (Figure 5.2). Wander interferes most with interpreting a chart recording or the operation of an electronic integrator. It can come either from the detector or from extraneous sources, such as a small leak at a column fitting. 

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. 

An automated solvent controller is available in the latest ASE system. It allows up to four solvents to be mixed and delivered to the extraction cells. This can reduce the time for measuring and mixing solvents and decrease users exposure to toxic solvents. The solvent controller can be programmed to change solvents between sequential extractions of multiple samples. The same sample can also be reextracted using different solvents. The ASE system has many built-in safety features, which include vapor sensors, liquid-leak detectors, vial overfill monitors, electronic and mechanical overpressurization prevention systems, solvent flow monitors, and pneumatic source pressure monitors. 

Industrial codes and standards for hydrogen are thus strict for a good reason. Some 22 percent or more of hydrogen accidents are caused by undetected hydrogen leaks.44 And this is despite the standard operating procedures, protective clothing, and electronic flame gas detectors provided to the limited number of hydrogen... 

Silicon oils do not break down on contact with air while hot, but on the other hand they can polymerize and develop an insulating film on electronics. Thus, their use is not acceptable for instruments such as mass spectrometers (including He leak detectors). Some specific properties of a spectrum of diffusion pump fluids are shown in Table 7.9. 

Silicone Fluids (IO 6 - IO 9) Are thermally stable and are resistant to oxidation and reasonably resistant to chemical attack. Are also reasonably priced. Form insulating polymeric layer when irradiated by electrons, so they cannot be used where physical electronic equipment is being pumped, such as in helium leak detectors. 

When helium leak detectors first became available, they were large and cumbersome and required highly trained technicians. They were also very expensive. Now, like most electronic equipment, they are smaller (relatively), easier to use (for some operations, they can be automated), less expensive, more reliable, more sensitive, and faster. As is typical of most things, helium leak detectors cannot have all the aforementioned attributes at once. However, it is possible to pick and choose which options are more important to you and select a detector that has features that are best suited to your needs. The usual tradeoff is sensitivity for speed. 

Helium has the distinction of being the smallest of all atoms. Both is electrons are pulled toward the nucleus more than in hydrogen and atoms of larger Z must place electrons in shells farther from the center. A practical consequence is in the technology of leak detectors for vacuum systems, because helium atoms entering through the smallest leaks can be counted and thereby locate the leak. 

Other methods of leak detection include using soap fluid with a little water in it, ultrasonic detectors, stethoscopes, feathers and electronic gas leak detectors. The reality of leak detection is that each method has its place, but each method is limited to certain leak characteristics. If one type of sensor does not show a leak, another may find it. 

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