Viewing ports

Figure 5-29. This view shows the conicai stainiess-steei backup piate ciosing the exhaust casing. The two fianged connections on the right are for the rotor biade viewing ports. The bearing housing is shieided from the backup piate by 3.5 in. (90 mm) of insuiation.

The Kel-F polychlorotrifluoroethylene view ports let us see what is happening on the hydrogen side of the screen (see later discussion). If it were really necessary to view the fluorine side, sapphire or diamond windows could probably be used. It is difficult to see below the electrolyte level of an operating cell because of gas bubbles. 

The conversion reactor was placed on a balance, which made it possible to monitor the mass loss rate of the fuel bed. The inner cylinder wall of the fuel bed section was a quartz glas tube, which was insulated with a 100 mm thick rockwool layer on the outside. The outer cylinder wall was a sheet-iron. A view port was used on the front of the pot for observation of the thermochemical processes taking place inside the fuel bed. 

Heat losses are a major issue in pilot and Oldershaw columns and can lead to optimistic scale-up. Special precautions are needed to keep these at a minimum. Vacuum jackets with viewing ports are commonly used. 

Lee etal. determined the concentration of glucose, acetate, formate, lactate, and phenylalanine simultaneously in two E. coli bioreactions using Raman spectroscopy.33 The bioreactor was modified to have a viewing port, and spectra were collected through the port window. This enabled researchers to sterilize the reactor and ensure that it would never be contaminated by contact with the instrument. 

Experimental differences between calibration work and routine use can introduce model error. The sapphire viewing port was used as a convenient, built-in reference sample. The calibration models were built before the reactor was sterilized. Unfortunately, the window material changed slightly during sterilization. The resulting subtle differences in the reference spectra collected before and after sterilization hurt the model s predictive ability. Reference samples are useful only if they are stable. 

Between the feeding system and the reactor there is a view port that is used to ignite the bed and acts as well as a safety pressure release valve. 

Apart from graphite tube furnaces, both cups and filaments are used as atomizers in electrothermal AAS [271]. The models originally proposed by L vov et al. [171] and by Massmann [172] were described in Section 3.4. In the case of the latter, which is most widely used, the optical beam is led centrally through the graphite tube, which is closed at both ends with quartz viewing ports mounted in the cooled tube holders. Sample aliquots are introduced with the aid of a micropipette or a computer controlled dispenser through a sampling hole in the middle of the tube. 

No air leaks Most of the ULNB use internal FGR to dilute the flame. Air leaks result in a high oxygen level in the flue gas that is recirculated and result in higher NO levels. Leaks into the furnace may need to be welded shut, and gaskets may need to be installed to stop air leaks around view ports. 

The main part of the apparatus is a cell, which can resist different chemicals, and is normally made of PTFE (poly tetrafluoroethylene). The cell is used to restrain the specimen during contact with the pressurized test liquid via a restraining ring. It consists of a chamber which can contain approximately 60 ml of the challenge liquid. The cell has an outer diameter of approximately 10 cm and an inner diameter of 6 cm. It has a viewing port which allows observation of the specimen during the test. 

An alternative method of presentation has been evolved which is useful in situations when repeated measurements have to be made on solid materials which have a high oil or fat content. These materials may smear or coat the surfaces of a glass cell. The method utilises clear PVC film (e.g., Saran Wrap). The film is stretched across the viewing port of the colorimeter and the sample is placed on the film. Measurement is made from below. After each measurement, the specimen can be quickly wrapped up in the film and discarded, thus eliminating the need for frequent washing of valuable glass sample cups (Mabon... 

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