Stainless Steel Filters

Quadrupole Hyperbolic, Mo Binary gold coated ceramic, producing hyperbolic field Mo rods with prepost filters Stainless steel rods locked into ceramic mounts, producing hyperbolic field... 

Adsorption of t-PA to process equipment surfaces consisting of either stainless steel or glass was minimized by adding the detergent polyoxyethylene sorbitan monooleate (Tween 80) to the semm-free culture conditioned media at 0.01% (vol/vol). The equipment was also rinsed, before use, with phosphate buffered saline (PBS) containing 0.01% Tween 80. Hydrophilic, plastic equipment was used whenever possible. AH buffers were sterile filtered. Sterile filtration of Hquids and gases is usually carried out using 0.2 or 0.45 p.m filters. 

Pentaerythritol may be nitrated by a batch process at 15.25°C using concentrated nitric acid in a stainless steel vessel equipped with an agitator and cooling coils to keep the reaction temperature at 15—25°C. The PETN is precipitated in a jacketed diluter by adding sufficient water to the solution to reduce the acid concentration to about 30%. The crystals are vacuum filtered and washed with water followed by washes with water containing a small amount of sodium carbonate and then cold water. The water-wet PETN is dissolved in acetone containing a small amount of sodium carbonate at 50°C and reprecipitated with water the yield is about 95%. Impurities include pentaerythritol trinitrate, dipentaerythritol hexanitrate, and tripentaerythritol acetonitrate. Pentaerythritol tetranitrate is shipped wet in water—alcohol in packing similar to that used for primary explosives. 

Extrusion. The filtered, preheated polymer solution is deHvered to the spinneret for extmsion at constant volume by accurate metering pumps. The spinnerets are of stainless steel or another suitable metal and may contain from thirteen to several hundred precision-made holes to provide a fiber of desired si2e and shape. AuxUiary filters are inserted in front of the fixture that holds the spinneret and in the spinneret itself to remove any residual particulate matter in the extmsion solution. 

For the production of tartar emetic (antimony potassium tartrate [28300-74-5]), potassium bitartrate [868-14 ] and antimony oxide, Sb202, are added simultaneously to water in a stainless-steel reactor. The reaction mixture is diluted, filtered, and collected in jacketed granulators where crystallization takes place after cooling. Centrihiging, washing, and drying complete the process. 

Porous parts and bearings are made by both the press and sinter techniques, whereas filters are made by loose powder sintering. The metals most commonly used for P/M porous products are bron2e, stainless steel (type 316), nickel-base alloys (Monel, Inconel, nickel), titanium, and aluminum. 

The manufacture of silver nitrate for the preparation of photographic emulsions requires silver of very high purity. At the Eastman Kodak Company, the principal U.S. producer of silver nitrate, 99.95% pure silver bars are dissolved in 67% nitric acid in three tanks coimected in parallel. Excess nitric acid is removed from the resulting solution, which contains 60—65% silver nitrate, and the solution is filtered. This solution is evaporated until its silver nitrate concentration is 84%. It is then cooled to prepare the first crop of crystals. The mother Hquor is purified by the addition of silver oxide and returned to the initial stages of the process. The cmde silver nitrate is centrifuged and recrystallized from hot, demineralized water. Equipment used in this process is made of ANSI 310 stainless steel (16). 

Microstrainers. Microstrainers are rotating steel screens with extremely fine stainless steel mesh (85—170 perforations per square centimeter (13—26/in. )). The flowing Hquid enters the open end of the dmm and passes through the mesh to the effluent end. The mesh traps soHd impurities and rotates with the dmm. A wash-water spray washes the trapped soHds into a hopper for final disposal. The mesh is washed with filtered effluent discharged from jets fitted into the dmm and then exposed to uv radiation to inhibit microbial growth. The mesh is washed with chlorine water at intervals of 7 to 28 days in order to control slime growth removal efficiencies are 30—55% of the appHed BOD and 40—60% of suspended soHds. 

Lime-Sulfuric. Recovery of citric acid by calcium salt precipitation is shown in Figure 3. Although the chemistry is straightforward, the engineering principles, separation techniques, and unit operations employed result in a complex commercial process. The fermentation broth, which has been separated from the insoluble biomass, is treated with a calcium hydroxide (lime) slurry to precipitate calcium citrate. After sufficient reaction time, the calcium citrate slurry is filtered and the filter cake washed free of soluble impurities. The clean calcium citrate cake is reslurried and acidified with sulfuric acid, converting the calcium citrate to soluble citric acid and insoluble calcium sulfate. Both the calcium citrate and calcium sulfate reactions are generally performed in agitated reaction vessels made of 316 stainless steel and filtered on commercially available filtration equipment. 

Spray Drying and Agglomeration. Most instant coffee products are spray-dried. Stainless steel towers with a concurrent flow of hot ak and atomized extract droplets are utilized for this purpose. Atomization, through pressure nozzles, is controUed based on selection of the nozzles, properties of the extract, pressures used, bulk density, and capacity requkements. Low inlet ak temperatures (200—280°C) are preferred for best flavor quaHty. The spray towers must be provided with adequate dust coUection systems such as cyclones or bag filters. The dried particles are coUected from the conical bottom of the spray drier through a rotary valve and conveyed to bulk storage bins or packaging lines. Processors may screen the dry product to... 

The calcium cyanamide feed is weU mixed with the recycled slurry and filtrate ia a feed vessel. The calcium cyanamide is added at a rate to maintain a pH of 6.0—6.5 ia the cooling tank. The carbonation step can be conducted ia a turbiae absorber with a residence time of 1—2 min. After the carbonation step, the slurry is held at 30—40°C to complete the formation of calcium carbonate, after which the slurry is cooled and filtered. AH equipment for the process is preferably of stainless steel. The resulting solution is used directiy for conversion to dicyandiamide. 

In order to upgrade the melamine, the solution obtained after prethickening and stripping is treated with activated carbon passed over a clarifying filter and fed to a two-stage vacuum crystallization system from which the pure melamine is recovered in a continuous centrifiige. Stainless steel is used as constmction material for nearly all parts of the equipment exposed to product streams. 

Plating T anks. An electroless plating line consists of a series of lead-lined (for plastics etching) or plastic-lined tanks equipped with filters and heaters, separated by rinse tanks (24). Most metal tanks, except for passivated stainless steel used for electroless nickel, cannot be used to hold electroless plating baths because the metal initiates electroless plating onto itself. Tank linings must be stripped of metal deposits using acid at periodic intervals. 

Disk Filters A disk filter is a vacuum filter consisting of a number of vertical disks attached at intervals on a continuously rotating horizontal hollow central shaft (Fig. 18-127). Rotation is by a gear drive. Each disk consists of 10 to 30 sectors of metal, plastic, or wood, ribbed on both sides to support a filter cloth and provide drainage via an outlet nipple into the central shaft. Each sector may be replaced individually. The filter medium is usually a cloth bag slipped over the sectors and sealed to the discharge nipple. For some heavy-duty applications on ores, stainless-steel screens may be used. 

When the pressure rises to the permissible maximum, the cartridge must be opened and the element replaced. Micronic elements of the fiber type cannot be cleaned and are so priced that they can be discarded or the filter medium replaced economically. Stone elements usually must be cleaned, a process best accomplished bv the manufacturer of the porous ceramic or in accordance with the manufacturer s directions. The user can clean stainless-steel elements by chemical treatment. 

Recently in some types of refuelling stations, corrosion-resistant materials have been used between the filter-water separator and the outlet pipeline and valves, usually stainless steel, rarely aluminum. If these are buried, they must have good insulating coating and be electrically separated from other tank installations by insulating couplings. 

In some service stations, stainless steel or aluminum materials are used for all the filters, pipes and fittings to maintain the purity of the fuel. The rest potentials of these materials are different from that of plain carbon steel (see Table 2-4). 

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