When a scope is used in atmospheres exposed to radiation, quartz fiberscopes are generally used. Alternatively, the temperature and resistance of the wire can be maintained at a constant value, and the required power input measured either directly or indirectly in terms of applied voltage or current. Cox General Dynamics Corporation Robert Cribbs Folsom Research Inc. Harper 1923-1926 Member, 1923-1926 C. The magnitude, respect, and success of this unprecedented reference set calls for a special tribute to its many supporters.
Heat losses are reduced as gas pressure is lowered. Anderson, American Gas and Chemical Company System Response The response of a leaking system to a leak is important in leak testing; if the response is too slow, it can be very time consuming to locate the leak, or the leak can be missed. The third section discusses the application of nondestructive methods to specific product types, such as one-piece products castings, forgings, and powder metallurgy parts and assemblies that have been welded, soldered, or joined with adhesives. Cooper 1984-1986 Member, 1981-1986 E. The use of a visible liquid penetrant for leak testing is only slightly limited by the configuration of the item to be inspected. However, leak-rate measurement can be accomplished by placing a calibrated leak over the probe tip to calibrate the leakdetector-tube-probe system. If leak location is the purpose of the test, methods that include the use of probes or portable detectors are necessary so that the surface of the test vessel can be scanned.
Extendable borescopes allow the user to construct a longer borescopic tube by joining extension tubes. Process engineers determined that tensile wire breaks were the cause of reported electrical continuity failures. The positive charge of the ions is imparted to the target, or collector, and the resulting current flow is proportional to the quantity of the ions of that particular mass. The laser Doppler velocity gage is a non-contact instrument that uses laser beams and microprocessors to measure the speed and length of a moving surface. As the stylus moves, the follower projects a contour on the screen. The pump reduces the response time, and the permeation membrane reduces the pressure drop into the mass spectrometer and also causes accumulation of the entering tracer, which increases sensitivity. Reference cited in this section 1.
Although most scopes can operate at temperatures from -34 to 66 °C -30 to 150 °F , especially designed scopes can be used at temperatures to 1925 °C 3500 °F. Leakage of gas through the discontinuity causes the indicator to change color. Detector cleanup time the time required for the leak detector to purge itself of tracer gas can range from a few seconds to several minutes, thus affecting the time between searches for a leak. Acoustic 1 to 10-2 1 to 10-2 Smoke tracer 1 to 10-2. Lasers are used in both of these functions.
Another method is to maintain the upstream pressure at a level high enough to produce flow of sonic velocity at the nozzle throat, thus making the leakage independent of upstream pressure. Maniar 1979-1980 Member, 1974-1980 J. However, if any changes must be made in a fixed system for any reason--for example, a different measurement of the same part or measurement of a different part--making the change will be costly and time consuming. However, the mean free path or the concentration of molecules controls such vacuum properties as viscosity, thermal conductance, and dielectric strength. The tube, which can be rigid or flexible with a wide variety of lengths and diameters, provides the necessary optical connection between the viewing end and an objective lens at the distant, or distal, tip of the borescope.
However, in the scanning, sorting, and triangulation applications described in this article, lasers are used because of the brightness, unidirectionality, and collimated qualities of their light; temporal coherence is not a factor. The purging occurs when a rather large leak is encountered and the probe tubing becomes filled with a high concentration of tracer gas. Ultrasonic leak detectors have also been successfully used with ultrasonic sound generators when the system to be tested could not be pressurized. Merten 1927-1930 Member, 1923-1933 N. Part Program and Data Storage. However, an extremely wide range of nondestructive testing methods are available to help the engineer to examine these different problems and various defects in an assortment of materials and under varying circumstances. In this technique, a finely focused laser spot of light is directed at the part surface.
If more than 3 h had elapsed before leak testing, the transistors were pressurized again. Zorc, Technical Editor; Heather J. Frissell, Editorial Supervisor; George M. A scan of the array determines the edge image location and then the location of the part edges from which the dimension of the part can be determined. Ionization gages will measure vacuums to 1.
However, some pressurized systems such as pipelines, lend themselves to leak testing by this method. Dornfield, Inspection and Quality Control in Manufacturing Systems, American Society of Mechanical Engineers, 1982 C. The constituents are detected as they leave the adsorbent column, usually by thermal-conductivity instruments, but they may also be detected by infrared analyzers or vapor-density balances. The thermal conductivity of a gas can be measured by a hot-wire bridge method Fig. Their efforts, combined with the considerable knowledge and technical expertise of literally thousands of authors, contributors, and reviewers, have resulted in reference books which are comprehensive in coverage and which set the highest standards for quality.