Wetted Materials of Construction

The amount of resin to pack in a column, column geometry, flow rates, pressure, column hardware, and wetted materials of construction should all be evaluated in development. Chromatography columns must be properly packed prior to validating the purification process. From a business perspective there should be some criteria other than purification of the product by which the quality of the packed column can be assessed prior to applying the feedstream, which by this time in the process is quite expensive. Height equivalent to a theoretical plate (HETP) and asymmetry determinations can be used to evaluate the quality of column packing, but may have limited value for some types of packed columns... 

Fig. 13.10 Flat top experiment, all stainless steel wetted materials of construction.

Materials of Construction. Glass has excellent corrosion-resistance to wet or dry bromine. Lead is very usefiil for bromine service if water is less than 70 ppm. The bromine corrosion rate increases with concentrations of water and organics. Tantalum and niobium have excellent corrosion-resistance to wet or dry bromine. Nickel has usefiil resistance for dry bromine but is rapidly attacked by wet bromine. The fluoropolymers Kynar, Halar, and Teflon are highly resistant to bromine but are somewhat permeable. The rate depends on temperature, pressure, and stmcture (density) of fluoropolymer (63). 

Standard materials for the compressor are cast iron for the cylinder and carbon steel for the shaft. The rotor parts are steel. The liquid pistf f compressor has another feature that compensates for low efficiency, using special materials of construction and compatible liquid compr sant, unusual or difficult gases may be compressed. By using titanium internal materials and water as a compressant, gases containing wet chlorine can be compressed. This is a very difficult application for most o( the other compressor types. 

Moist chlorine is corrosive to skin and to most common materials of construction. Wet chlorine at low pressure can be handled in chemical stonewear, glass or porcelain and in certain alloys and plastics. 

Note that when packing is changed from one material of construction to another, it is important to recognize the effect on minimum wetting rate for the new condition. 

Air/water vapor mixture, chart, 364,365 Air/water vapor, 359 Capacity at ejector suction, 369 Capacity for process vapor, 362 Evacuation time, 371, 380 Load for steam surface condenser, 367 Non-condensables, 362, 363 Size selection, 371 Steam pressure factor, 373 Steam requirements, 372 Steain/air mixture temperature, 361 Total weight saturated mixture, 362 Capacity, 358 Discharge, pressure, 358 Effect of excess steam pressure, 358 Effects of back pressure, 359 Effects of wet steam, 356 Inter-and-after condenser, 351 Load variation, 370 Materials of construction, 347 Molecular weight entrainment, chart, 360 Performance, 358, 370, 375 Relative comparison, 357... 

The dispersed phase should be the one that has the higher volumetric rate except in equipment subject to backmixing where it should be the one with the smaller volumetric rate. It should be the phase that wets the material of construction less well. Since the holdup of continuous phase usually is greater, that phase should be made up of the less expensive or less hazardous material. 

The capital costs associated with wet oxidation depend on several factors such as capacity of the system, oxygen demand of the wastewater, the properties of the waste to be treated, and the materials of construction of the system. Operating costs of the system are a function of the capacity of the unit, and the external energy requirements. (D16657Y, p. 8.88). 

Range of instrument and manufacturer s accuracy Materials of construction, especially of process contact (wetted) parts Process connection details (e.g., chemical seals, capillary lengths, flange rating)... 

When wetting or underwetting effects are likely, pilot-test at the composition range expected in the prototype. Also, use identical materials of construction and surface treatment in the pilot tests and the prototype. 

The facilities engineer must consider the materials used to construct the wetted parts of the unit operations used to treat the waste. The goal is to select a cost-effective material that will not degrade in the presence of the waste stream to be treated. In general, the most commonly used materials of construction for the unit operations are 316or316L stainless steel. However, if chlorides, fluorides, and other halogens are present in the CMP chemistry, it may be necessary to consider nickel, titanium, Hastelloy, or other high-performance metals. 

Range of instrument (calibrahon range) or switch set point values Materials of construction of wetted parts Control characterishcs... 

To ensure the cleanliness of the ceramic membrane gas filters, the housing typically made of stainless steel should have electropolished internal wetted surfaces and welded parts free of flux materials. In addition, considerations need to be given to the materials of construction for housing (e.g., stainless steel) and seals. 

Materials of construction for wetted portions of the instrumentation must be selected using similar considerations to those used for the equipment itself. In addition, plastic diaphragm seals are available to cover and protect the pressure-sensing faces of immersed level transmitters. This allows the use of stainless steel in apph-cations where, if unprotected, the corrosion rate would be unacceptably high on the thin face of the instrument. A diaphragm seal is recommended for pressure instruments in the presence of suspended or entrained solids. 

---