Automatic drying

Figure 38. Exaanple of aa Automatic Dry Polymer Feed System. 311...

Figure 38. Example of an automatic dry polymer feed system.

In addition to the sprinkler system adequacy, is additional fire protection, such as an automatic dry chemical extinguishing system or a other system, warranted Is an explosion suppression system warranted ... 

Small batches and large articles are made. The automatic dry bag process is used to mass-produce small articles such as spark plug insulators. The pressure medium is a gas. Isostatic pressing avoids problems of die-wall friction but does not provide as accurate tolerances as die-pressing. The process was invented by H. D. Madden (US Pat. 1081 618, (1913). 

Automatic dry polymer dilution systems can be used to perform the wetting, diluting, and mixing functions however, the system must be manually recharged with dry polymer periodically. Although costly, these systems can save time and usually improve consistency. 

Commercial instruments also provide for automatic drying of moisture from the trap, baking the trap at elevated temperatures between runs, and may include special options to handle water vapor from liquid samples, cryogenic ability for cold trapping, cryogenic refocusing on the GC column for sharper peaks, and automation of multiple samples. 

The purified commercial di-n-butyl d-tartrate, m.p. 22°, may be used. It may be prepared by using the procedure described under i o-propyl lactate (Section 111,102). Place a mixture of 75 g. of d-tartaric acid, 10 g. of Zeo-Karb 225/H, 110 g. (136 ml.) of redistilled n-butyl alcohol and 150 ml. of sodium-dried benzene in a 1-litre three-necked flask equipped with a mercury-sealed stirrer, a double surface condenser and an automatic water separator (see Fig. Ill, 126,1). Reflux the mixture with stirring for 10 hours about 21 ml. of water collect in the water separator. FUter off the ion-exchange resin at the pump and wash it with two 30-40 ml. portions of hot benzene. Wash the combined filtrate and washings with two 75 ml. portions of saturated sodium bicarbonate solution, followed by lOu ml. of water, and dry over anhydrous magnesium sulphate. Remove the benzene by distillation under reduced pressure (water pump) and finally distil the residue. Collect the di-n-butyl d-tartrate at 150°/1 5 mm. The yield is 90 g. 

The main features in which the Radford process differs from the batch operation are in thermal dehydration and compounding. Water-wet nitrocellulose on a continuous vacuum belt filter is vacuum-dried followed by hot air transfusion (80°C) to reduce the moisture to less than 2%. After cooling, alcohol is sprayed on the nitrocellulose to a concentration of 15—20%. The alcohol-wet nitrocellulose is then transferred from a surge feeder to a compounder by a continuous weigh-belt along with the other ingredients of the composition, which are also weighed and added automatically. 

Most cleaners are available for < 2.20/kg either as a dry blend or as aHquid. Liquid cleaners are usually less expensive than the dry blend type. A trend toward Hquid cleaners is evident as of this writing (ca 1994) because of convenience features such as automatic additions of the cleaner by chemical feed pump. Safety features such as minimized heat generation upon blending with water to make the desired concentration are also important. 

Centrifugal Sedimentation Equipment. Commercial sedimentation centrifuges are characterized priacipaHy by how soHds are discharged, and the general dryness of these soHds. There are batch and automatic batch soHd bowl machines which coUect the soHds at the bowl wall. SoHds are removed very dry. Almost any soHd is coUectable, even those that are very soft and compressible. 

Phospha.tes, Pentasodium triphosphate [7758-29-4] sodium tripolyphosphate, STPP, Na P O Q, is the most widely used and most effective builder in heavy-duty fabric washing compositions (see also Phosphoric acid and phosphates). It is a strong sequestrant for calcium and magnesium, with a p c of ca 6, and provides exceUent suspending action for soils. Because of its high sequestration power, it also finds extensive appHcation in automatic-dishwashing detergents. Sodium tripolyphosphate forms stable hydrates and thus aids in the manufacture of crisp spray-dried laundry powders. 

Humidity can be a problem. Whereas it was shown (284) that 33% RH was best for spore inactivation, and that at least 30% RH was needed for effective sterilisation (285), dried spores are difficult to kill, and the spore substrate material and wrappings compete with the spore for the available moisture (286). Therefore, the relative humidity is adjusted to 50—70% to provide sufficient moisture for the spores to equiUbrate. The exposure time depends upon the gas mixture, the concentration of ethylene oxide, the load to be sterilised, the level of contamination, and the spore reduction assurance requited. It may be anywhere from 4—24 hours. In a mn, cycles of pre-conditioning and humidification, gassing, exposure, evacuation, and air washing (Fig. 9) are automatically controlled. 

If an ethyl ether fire occurs, carbon dioxide, carbon tetrachloride, and dry chemical fire extinguishers meeting National Eire Prevention Association Code 1 and 2 requirements may be used successhiUy (23). Water may also be effectively appHed (see Plant safety). Hose streams played into open tanks of burning ethyl ether serve only to scatter the Hquid and spread the fire. However, ether fires may be extinguished by a high pressure water spray that cools the burning surface and smothers the fire. Automatic sprinklers and deluge systems are also effective. 

When the mean annual temperature is 16.7°C (30°F) lower than the design dry-bulb temperature and when both fans in a bay have automatically controllable pitch of fan blades, annual power required has been found to be 22, 36, and 54 percent respectively of that needed at the design condition for three process services [Frank L. Rubin, Tower Requirements Are Lower for Air-Cooled Heat Exchangers with AV Fans, Oil Gas J., 165-167 (Oct. 11, 1982)]. Alternatively, when fans have two-speed motors, these dehver one-half of the design flow of air at half speed and use only one-eighth of the power of the full-speed condition. 

Current designs for venturi scrubbers generally use the vertical downflow of gas through the venturi contactor and incorporate three features (I) a wet-approach or flooded-waU entry sec tion, to avoid dust buildup at a wet-dry pmction (2) an adjustable throat for the venturi (or orifice), to provide for adjustment of the pressure drop and (3) a flooded elbow located below the venturi and ahead of the entrainment separator, to reduce wear by abrasive particles. The venturi throat is sometimes fitted with a refractoiy fining to resist abrasion by dust particles. The entrainment separator is commonly, but not invariably, of the cyclone type. An example of the standard form of venturi scrubber is shown in Fig. 17-48. The wet-approach entiy section has made practical the recirculation of slurries. Various forms of adjustable throats, which may be under manual or automatic control. 

Automatic filters are made with either viscous-coated or dry filter media. However, the cleaning or disposal of the loaded medium is essentially continuous and automatic. In most such devices the air passes horizontally through a movable filter curtain. As the filter loads with dust, the curtain is continuously or intermittently advanced to expose clean media to the air flow and to clean or dispose of the loaded medium. Movement of the curtain can be provided by a hand crank or a motor drive. Movement of a motor-driven curtain can be actuated automatically by a differential-pressure switch connected across the filter. 

A unit is available in which electrostatic precipitation is combined with a dry-air filter of the type shown in Fig. 17-64Z . In another unit an electrostatic field is superimposed on an automatic filter. In this case the ionizer wires are located on the leading face of the unit, and the collecting electrodes consist of alternate stationary and rotating parallel plates. Cleaning in this case is automatic and continuous. 

Electrostatic method This is also a w et method like the conventional process, except that the paint is now electrostatically charged, similar to the powder ptiint in a dry method as discussed later. The paint, being highly charged electrostatically, is wrapped around the object automatically. 

Perfluorobutyric acid [375-22-4] M 214.0, m -17.5", b 120"/735mm, d 1.651, n 1.295, -0.17. Fractionally distd twice in an Oldershaw column with an automatic vapour-dividing head, the first distn in the presence of cone H2SO4 as a drying agent. 

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