Sanitary Seal

Figure 6.2 Joint types (a) butt joint (b) expansion joint (c) (i) glass-to-glass lap joint, (ii) concrete-to-concrete lap joint (d) triangular joint (e.g. sanitary seals and glazing seals). H = sealant S = backing material [part (c)]...

Because of its elastic recovery properties, PTFE, a self-lubricating compound, is used in sealing and flexing applications such as sanitary seals, valve diaphragms, o-rings in mechanical seals, and seals and seats of stem and rotary valves such as ball valves. It is also commonly used as a liner or coating material for valves and pumps for the pharmaceutical industry. 

Joaquin Valley, California. Selection was based on well sampling survey results conducted during the summer of 1983 (5). Both soil coring locations consisted of agricultural fields as close as possible to one of the previously sampled wells. Location 1 was 62.0 meters from a domestic well 42.7 meters deep where EDB residues were detected. The well had a sanitary seal 6.0 meters deep and was perforated between 31.4 and 37.5 meters. Location 2 was 111 meters from a domestic well 36.6 meters deep where EDB residues were not detected. This well also had a sanitary seal 6.0 meters deep and was perforated from 31.0 to 34.0 meters. 

During the drought year, 1977, over 20,000 new wells were drilled in California with nearly half of these in the Central Valley. The rate of well construction and abandonment is increasing by approximately 5 percent per year. Current state standards do not require sanitary seals on most agricultural wells. Thus, unless action is taken to reverse this situation, the problem of poorly sealed or repaired water wells which allow surface pollutants to reach ground water is likely to increase. 

It appears that the only approach that appears to be viable would be the one in which the product is contained in a replaceable, access restricted package that protects the product and the consumer from overexposure and cross-contamination. Examples of low to medium risk bulk dispensers would include dispensers that minimize direct contact with the nozzle, utilize automatic rather than manual dispensing, and restrict easy access to the bulk compartment. By far the safest dispensers are those that use replaceable sanitary sealed bags or cartridges that include a new nozzle or delivery device. 

The primary non-woven applications for hot melts are in disposable articles such as diapers and sanitary napkins (see Fig. 22). These articles are made by high speed processes and are immediately packaged in sealed plastic bags, thus they are prime candidates for hot melt use. The applications are broken down into three categories, requiring three different types of adhesives construction, elastic attachment, and garment attachment. 

Pumps should be of sanitary design with seals that prevent contamination of the water. 

Figure 3.45 By perforating the antitelescoping device, a small controlled bypass of fluid past the module seal is achieved to eliminate the stagnant area between the reverse osmosis module and the pressure vessel walls. This device is used in food and other sanitary applications of spiral-wound modules [115], Reprinted from Reverse Osmosis Technology, B.S. Parekh (ed.), Marcel Dekker, New York (1988), p. 359, by courtesy of Marcel Dekker, Inc.

The water circulation pump must be of sanitary design and may be equipped either with a single or a double mechanical seal. In the latter case, the purified water from the pump s discharge is used as a seal flush fluid (Fig. 5). If a spare circulation pump is installed for reliability, it is important to ensure that it does not constitute a long dead leg. This can be avoided either by valving it off and draining it free of water... 

Most of the room temperature crosslinking silicone rubbers are utilized for filling holes in buildings e.g. so-called expanding fillers, in the sanitary sector and for the sealing of windows. 

After filling, it remains to cap the cans or put the lids on, cook the contained fish, seal, clean, and label. The canning process involving the use of soldered cans has been supplanted almost entirely by that based on the use of the solderless or so-called sanitary can. The latter process, being almost entirely automatic, effects a great saving in labor as well as floor space, and is commendable from both a mechanical and a sanitary point of view. 

SPILL CLEAN-UP absorb as much as possible in dry earth or sand deposit in sealed containers or place in a secured sanitary landfill remove all ignition sources. 

DISPOSAL AND STORAGE METHODS chromic acid and chromates may be disposed of in sealed containers in a secured, sanitary landfill store in a cool, dry location maintain adequate ventilation separate form combustible materials, halogens, sulfides, and metals. 

DISPOSAL AND STORAGE METHODS absorb spilled material in dry earth or sand, and bury in a sanitary landfill store in tightly sealed containers storage should be in a cool, dry, well-ventilated area away from heat and ignition sources. 

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