Water-cleanable

Modem latex paints are based on acrylic (ethyl and other acrylates) latices because of the acrylic s superior chemical stability and, therefore, resistance to color change and degradation. Most water-cleanable house paints today are based on acrylic latex. 

Figure 11-69 describes a typical central system. Either water or direct-expansion refrigerant coils or air washers may be used for cooling. Steam or hot-water coils are available for heating. Humidification may be provided by target-type water nozzles, pan humidifiers, air washers, or sprayed coils. Air cleaning is usually provided by cleanable or throwaway filters. Central-station air-conditioning units in capacities up to about 50,000 cu ft/min are available in prefabricated units. 

Otner Collectors Tarry particulates and other difficult-to-handle hquids have been collected on a dry, expendable phenol formaldehyde-bonded glass-fiber mat (Goldfield, J. Air Pollut. Control A.SSOC., 20, 466 (1970)] in roll form which is advanced intermittently into a filter frame. Superficial gas velocities are 2.5 to 3.5 m/s (8.2 to 11.5 ft/s), and pressure drop is typically 41 to 46 cm (16 to 18 in) of water. CoUection efficiencies of 99 percent have been obtained on submicrometer particles. Brady [Chem. Eng. Prog., 73(8), 45 (1977)] has discussed a cleanable modification of this approach in which the gas is passed through a reticulated foam filter that is slowly rotated and solvent-cleaned. 

Sinks supplied to clean areas should be made of stainless steel and have no overflow, and the water should be of at least potable quahty. Wherever possible, drains in clean areas should be avoided. If installed, however, they should be fitted with effective, easily cleanable traps and with air breaks to prevent backflow. Any floor channels in a clean area should be open, shallow and cleanable and should be connected to drains outside the area. They should be monitored microbiologically. Sinks and drains should be excluded from aseptic areas except where radiopharmaceutical products are being processed when sinks are a requirement. 

Porcelain enamels meet a variety of performance characteristics required for different applications. The common characteristics of all enamels include good adherence to the substrate and good thermal expansion lit to the metal. Specific properties depend on usage for example, acid and alkali resistance, hot water resistance, abrasion resistance, thermal shock resistance, high gloss, high reflectance, specific color, heat resislance. and cleanability. 

Aqueous Cleanable. All parts should preferably be cleanable in water or a safe solvent, unless they come out of the production process clean enough to be double-bagged and shipped directly to the clean-room assembly area. When soldering is involved, for example, the specification should call out for the use of water-soluble or noclean fluxes. Parts and assembly design should allow suppliers to quickly switch to a non-CFC solvent. 

Glassware and glass-lined equipment also offer excellent resistance to corrosion, similar to that of ceramic materials. In addition to the advantages of corrosion resistance, it also affords a very cleanable surface. Glass-lined vessels are used in the pharmaceutical industry for reactors, mixers, storage tanks, transfer piping, and high-purity water systems. 

Fig. 4 Multipurpose room with an easily cleanable covered terrazzo floor, dry-wall fiberglass mat with epoxy-painted walls, floor drain, and utility panel. The room has a self-contained hot and cold water wash-down capability.

Downward-facing surfaces should not trap or absorb water and should be cleanable. 

The isolation/purification facilities will be designed with GMP considerations consistent for the final stage of the product. Some of those considerations include product isolation and separation (Fig. 5), cleanable surfaces, purified water systems, and temperature, airfiow, and humidity controls. 

---