Slit perforation

The chief disadvantages of a Buchner funnel for filtration are (i) it is impossible to see whether the underside of the perforated plate is perfectly clean, and (ii) the larger sizes are top heavy. The first drawback is absent in the Jena slit-sieve funnel (Fig. 11,1, 7,/) this is an all-glass funnel provided with a sealed-in transparent plate, perforated by a series of angular slots, upon which the filter paper rests. The sintered glass... 

Protection of the Detector. With all direct calibration methods the primary beam intensity must be measured. If the primary beam itself is attenuated, shape of the beam and spectral composition of the radiation may be altered. This problem is avoided if the load of the detector is reduced by scanning the beam using a slit or a perforated disc. On the other hand, in order to be useful at a powerful synchrotron beamline these devices should have very tiny and well-defined slits or holes. 

The lay-flat film is then either kept as such or the edges of the lay-flat are slit off to produce two flat film sheets and wound up onto reels. If kept as lay-flat, the tube of film is made into bags by sealing across the width of film and cutting or perforating to make each bag. This is done either in line with the blown film process or at a later stage. 

For a large quantity of precipitate, a small Buchner funnel (b in Fig. II.9, shown enlarged for the sake of clarity) is employed. This consists of a porcelain funnel in which a perforated plate is incorporated. Two thicknesses of wellfitting filter paper cover the plate. The Buchner funnel is fitted into the filter flask by means of a cork. When the volume of liquid is small, it may be collected in a test-tube placed inside the filter flask. The Jena slit sieve funnel, shown in c, is essentially a transparent Buchner funnel its great advantage over the porcelain Buchner funnel is that it is easy to see whether the funnel is perfectly clean. 

Fig. 66 shows the bottomhole of an injection well used for testing of the in situ combustion method by Mene Grande Oil Company in an oil rield of eastern Venezuela. In this design of the injection well, the annular space is sealed with a packer. Perforated slits, suspended liner, and a gravel rilter are employed to prevent sand from plugging up the well. 

The back-scattered fluorescence is collected back up the same fiber, reflected from the mirrored face of the perforated mirror (PM), and imaged by another lens onto the entrance slit of a monochromator (SLM-Aminco, Inc.) with a spectral band-pass of 8 nm. Fluorescence is detected with another photomultiplier tube (D), identical to the reference channel unit. The cross-correlation (heterodyne) frequency (16,18) is produced with a second PTS 500 frequency synthesizer amplified by a 5W power amplifier (PA2 Amplifier Research, model 5W1000). The output from this amplifier is directed simultaneously to the second dynodes of the both reference and detection photomultiplier tubes using a simple power splitter (PS Adam Russell, model H-9). The cross-correlation frequency employed for this instrument is 25 Hz. 

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