Pinholes detection

Steel Structure Paint Council white metal blast surface preparation Proposed test method for pinhole detection by high-voltage spark testing by DC... 

Used with materials which can be detected by interaction, i.e. ammonia on one side, hydrochloric acid gas on the other (formation of white cloud of ammonium chloride indicates transfer and leakage). This type of test has been used for pinhole detection. 

Excitation and detection geometry. The sample volume from which the fluorescence is detected can differ considerably. In two-photon imaging the excited volume is of the order of 0.1 pm. Confocal imaging with a wide pinhole detects from a considerably larger sample volume. Consequently, the fluorescence comes from a larger number of molecules, and a correspondingly higher intensity is available. The majority of FLIM experiments are performed in two-photon systems with a small focal volume and low intensity. 

Porotest, Pinhole detection device, Electro-Physik... 

The overall reaction takes place at a rate determined by the more difficult of these two steps. This simple concept, independent anodic and cathodic half-reactions, is the basis of the electrochemical mechanism of corrosion. The mechanism has profound effects on the corrosion protective properties of nonmetallic coatings materials. Some tests exploit the electrochemical mechanism to determine specific corrosion susceptibilities of coatings systems such as cathodic disbond-ment and pinhole detection. Coatings that are permeable to oxygen may be vulnerable to damage due to an alternative cathodic reaction... 

In enamels for chemical plant such as autoclaves it is not only the degree of acid resistance which is important but also the freedom of the finish from minute flaws detectable by high frequency spark testing or chemical methods. The chemical methods depend upon a colour change when the reagent such as ammonium thiocyanate reacts with the iron exposed at the bottom of the pinhole or flaw in the finish. Alternatively, an electric cell can be formed via the exposed iron in the flaw and detected chemically. 

Holiday Detector a high-voltage low-current output generator with a built-in spark gap used for detecting pinholes (holidays) in pipeline coatings. 

The very first spectroscopic instruments, from Newton s prism and pinhole to Frauenhofer s simple spectroscope, were constructed to observe luminescence. Even though the great sensitivity of luminescence detection seemed to promise that luminescence would become an important tool for chemical analysis, the fact is that absorption spectroscopy was the first spectroscopic technique to be widely used. At first glance, this may seem surprising since absorption spectroscopy is inherently less sensitive and had to await the development of more complex instrumentation, especially, electronically amplified detection. 

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. 

Figure 10. Optical setup for LDA consisting of a laser beam being split and focused by a lens through a suspension of particles in a sample cell. Scattered light is focused through a pinhole and detected by a photomultiplier tube.

Fig. 2. Depth discrimination (z-axis resolution) properties of a confocal microscope. The illumination and detection images in a confocal microscope are diffraction-limited and confined to a small region of the specimen (1). Only light emitted in the plane of focus and on the optical axis will pass the detector pinhole and form an image. Light emitted from other areas of the specimen does not enter the detector pinhole.

AFM (cp-AFM). This specific measurement detects highly local and isolated penetration spots caused by either static pinholes or local blocking of a thiol terminal group at the SAM/vacuum interface due to some local disorder in the SAM. 

If there is a pinhole in the glass which is sufficiently large, it will attract the discharge from the Telsa coil in the form of a long blue spark which ends on the glass surface at the pinhole in a sharp, blue-white point fortunately, leaks too small to be detected by the Tesla discharge are extremely rare. 

Spark tester - A high voltage test unit used to detect breaks or pinholes in a lining. 

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