Cleanable

The tubeside fluid must be clean or at least chemically cleanable. With a large number of tubes in the coil, cleaning of inside surfaces is not totally rehable. Fluids that attack stressed materials such as chlorides should be reviewed as to proper coil-material selection. Fluids that contain sohds can be a problem due to erosion of relatively thin coil materials unlike the thick plates in spiral-plate units and multiple, parallel, fluid passages compared to a single passage in spiral-plate units. 

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. 

Cleanable Granular-Bed Filters The principal objective in the development of cleanable granular-bed filters is to produce a device that can operate at temperatures above the range that can be tolerated with fabric filters. In some of the devices, the granules are circulated continuously through the unit, then are cleaned of the collected dust and returned to the filter bed. In others, the granular bed remains in place but is periodically taken out of service and cleaned by some means, such as backflushing with air. 

Air-Filter Types Air filters may be broadly divided into two classes (1) panel, or unit, filters and (2) automatic, or continuous, filters. Panel filters are constructed in units of convenient size (commonly 20- by 20-in or 24- by 24-in face area) to facilitate installation, maintenance, and cleaning. Each unit consists of a cleanable or replaceable cell or filter pad in a substantial frame that may be bolted to the frames of similar units to form an airtight partition between the source of the dusty air and the destination of the cleaned air. 

FIG. 17-64 Typical dry filters, (a) Throwaway type, Airplex. (Davies Air Filter Coij)oration.) (h) Replaceable medium type, Airmat PD24, cutaway view. (Ameiican Air Filter Co., Inc. ) (c) Cleanable type, Amirglass sawtooth. (Ami iion Company.)... 

Tube interiors cleanable difficult to do mechanically can do chemically yes, mechanically or chemically yes, mechanically or chemically yes, mechanically or chemically yes, mechanically or chemically... 

Tube exteriors with triangular pitch cleanable chemically only chemically only chemically only chemically only chemically only... 

Cleanable A filter that can be cleaned by manual or automatic washing. 

Cellular Replacement filter elements, which may be installed in a multiple, bark, or wall structure. Cleanable A filter that, having collected a given amount of particulate matter, can he removed from the filter frame, cleaned, and reused. 

Disposable The opposite of a cleanable filter, which after collecting a certain dust burden is thrown away. Dry cell panel A dry filter mounted in a rigid frame. In the past these were manufactured from woven fabrics and felts however, synthetic fibers are replacing these. They have fiber diameters of 20 pm with average spacing of 300 pm and allow air velocity in the 2 m s-1 range. 

Filter elements may be of the 5-micron, woven mesh, micronic, porous metal, or magnetic type. The micronic and 5-micron elements have non-cleanable filter media and are disposed of when they are removed. Porous metal, woven mesh and magnetic filter elements are usually designed to be cleaned and reused. 

That the authorities have refused unreasonably to accept compliance with alternative requirements or that the requirements of the notice are otherwise unreasonable in character or extent, or are unnecessary. This defense is self-explanatory. The local authorities are only permitted to ask for works that will abate the noise nuisance. Other works (perhaps to comply with legislation) should not be specified in the notice. They may, however, be contained in a letter separate from the notice. An example of this would be where the fitting of acoustic enclosures to food-manufacturing machines breached food hygiene requirements. Readily cleanable enclosures may be a requirement of the Food Hygiene Regulations, but it should not be contained in a Section 58 Control of Pollution Act notice. 

The interior surface finish, to comply with EEC and other health standards, must be rustproof, cleanable, and free from any crevices which can hold dirt. Bare timber in any form is not permitted. Most liners are now aluminium or galvanized steel sheet, finished white with a synthetic enamel or plastic coating. GRP liners are also in use. Floors are of hard concrete or tiles. Very heavy working floors may have metal grids let into the concrete surface. Floor concrete is coved up at the base of the walls to form a protective curb. 

The filter must be cleanable or reasonably cheap to replace... 

Heat exchangers for liquids will be double pipe, shell-and-tube and plates (see Figures 6.3, 6.4 and 17.1). Waste fluids may be contaminated by the process, and heat exchangers for such fluids must be cleanable, and kept clean. 

Furniture Work stations Hospital furniture Office furniture Outdoor furniture Flame retardance, appearance Flame retardance, cleanability Flame retardance, cost Weatherability, cost... 

In the laboratory, alkyd paints are preferable due to their durability and cleanability. Although latex paints have come a long way since their development, they do not measure up to the alkyd variety in laboratory applications. The popular latex enamels, in particular, are inferior to a good alkyd enamel. They are hard to apply smoothly and they pick up dirt far too fast. 

Clean and aseptic areas must be adequately illuminated lights are best housed above transparent panels set in a false ceiling. Electrical switches and sockets should fit flush to the wall. When required, gases should be piped into the area from outside the unit. Pipes and ducts, if they have to be brought into the clean area, must be effechvely sealed through the walls. Additionally they must either be boxed in (which prevents dust accumulation) or readily cleanable. Alternatively, pipes and ducts may be sited above false ceilings. 

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. 

In order to characterize the cleanability of a coal, washability tests are typically performed for a range of particle sizes and... 

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