Gaskets membrane materials

There are special applications where it is required that essentially no dissolution or reaction takes place between the membrane/module material and the process stream. One such application area is food and beverages. For these uses, not only the membrane material but also the housing and gasket materials need to pass certain tests for sanitary reasons (e.g., FDA approval). Stainless steel (especially the 316L type) is typically used as the casing material and fluorinated polymers, EPDM, silicon or other specialty... 

Disc/flat-sheet membrane reactors are mostly applied in research work because they can be fabricated easily in laboratory with a small amount of membrane material. Figure 7.11 shows the structure of the disc/flat-sheet membrane reactor. The membrane disc is mounted between two vertical ceramic or quartz tubes, and then placed in a bigger quartz tube. Pyrex or gold gaskets are used to obtain an effective seal between the disk and the walls of the inner tubing at high temperatures by placing the assembly in... 

Fouling Industrial streams may contain condensable or reactive components which may coat, solvate, fill the free volume, or react with the membrane. Gases compressed by an oil-lubricated compressor may contain oil, or may be at the water dew point. Materials that will coat or harm the membrane must be removed before the gas is treated. Most membranes require removal of compressor oil. The extremely permeable poly(trimethylsilylpropyne) may not become a practical membrane because it loses its permeability rapidly. Part of the problem is pore collapse, but it seems extremely sensitive to contamination even by diffusion pump oil and gaskets [Robeson, op. cit., (1994)]. 

Confirm the selection of membrane and gasket material for a full-scale facility. 

Auxiliary equipment and fittings that require seals, gaskets, diaphragms, filter media, and membranes should exclude materials that permit the possibility of extractable, shedding, and microbial activity. 

D. Little, Inc., report for Contract 210-76-0130 to the National Institute for Occupational Safety and Health(11) and are shown in Fig. 1. The cell was constructed of Pyrex 1720 glass with stainless steel membrane holders and stainless steel top covers. Gaskets for the cell were constructed from Teflon (trademark DuPont) with the test material placed between the gaskets and with the bolts tightened to a torque of 5 2.5 pounds. This torque was chosen because values less than 2.5 in pounds did not seal the protective material firmly,and torques greater than 7.5 in pounds would put such pressure on the material that it would tear or degrade rapidly at the points of contact. 

All spiral wound modules also have a brine seal (see Figures 4.23a and 4.23b). The brine seal is a U-cup-shaped rubber gasket material that is used to prevent feed water from passing by on the outside of the membrane module, thereby preventing feed water from bypassing the membranes (see Figure 4.24). The brine seal... 

Chemical compatibility of construction materials of inorganic membrane, gaskets, header plates and housing with various chemical reagents... 

Plate modules are mainly used for dehydration applications, with stainless steel used as construction material for support plates for the membranes and for spacers. Gaskets are normally graphite based and... 

The L79 is easy to build and uses a few common materials in a unique way (see illustration, next page). It consists of a six layered sandwich composed of one PVC end plate, two PC (printed circuit) board elec-trode/gas flow field plates, one 12 PEM MEA (membrane electrode assembly) layer, and 2 rubber gaskets, one of which also acts as a gas supply line. 

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