Fittings, clean areas

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. 

All operations (cleaning, filtration, acidification and sample handling) were carried out in a specially designed Class 100 room, either fitted in a standard 20 ft transport container which was fully equipped as a chemical laboratory or in a room transformed as such on board of the research ship. All operations with the sample were performed in a closed system, except for the sample acidification and the filling of the bottles, which were performed in a laminar flow clean bench inside the clean room. All personnel working in the clean area used polythene gloves, dust-free garments and shoe-covers. 

As far as practicable, equipment, fittings and services should be designed and installed so that operations, maintenance and repairs can be carried out outside the clean area If sterilisation is required, it should be carried out after complete reassembly wherever possible. 

To reduce accumulation of dust and to facilitate cleaning, there should be no hidden difficult-to-clean recesses and a minimum of projecting ledges, shelves, cupboards, equipment, fixtures and fittings. Covin c should be used where walls meet floors and ceilings in sterile areas and other clean areas. 

The number of laboratories used will depend on the space and funds available, and also on the estimated number of samples. There should be at least one laboratory available for the counting and identification of bacterial samples, with a separate media kitchen or clean area for the preparation and sterilisation of media. A separate area should also be available as a dirty area for the disposal of used materials. It has to be accepted however that it is not an ideal world, and frequently a new laboratory has to be fitted into available space rather than designed from the beginning on first principles. 

An obvious method of increasing the filtration area in the vessel is to stack several plates on top of each other the plates are operated in parallel. One design, known as the plate filter, uses circular plates and a stack that can be removed as one assembly. This allows the stack to be replaced after the filtration period with a clean stack, and the filter can be put back into operation quickly. The filter consists of dimpled plates supporting perforated plates on which filter cloth or paper is placed. The space between the dimpled plates and the cloth is coimected to the filtrate outlet, which is either into the hoUow shaft or into the vessel, the other being used for the feed. When the feed is into the vessel, a scavenger plate may have to be fitted because the vessel will be full of unfiltered slurry at the end of the filtration period. This type of filter is available with filtration areas up to 25 m and cakes up to 50 mm thick. 

A normal enclosure is meant for a reasonably clean atmosphere and a relative humidity not more than 50% for LT and 95% for FIT indoor enclosures. Where the atmosphere is laden with fumes or steam, saline or oil vapours, heat and humidity, excessive dust and water or contaminated with explosive and fire hazardous gases, vapours or volatile liquids (Section 7.11) a special enclosure with a higher degree of protection is required as in lEC 60529 or lEC 60079-14. For non-hazardous areas, the enclosure can be generally one of those discussed in Tables 1. 10 and 1. 11, and when required can be provided with special treatment to the metallic surfaces. For hazardous areas, however, special enclosures will be essential as discussed in Section 7.11. 

The above measurements all rely on force and displacement data to evaluate adhesion and mechanical properties. As mentioned in the introduction, a very useful piece of information to have about a nanoscale contact would be its area (or radius). Since the scale of the contacts is below the optical limit, the techniques available are somewhat limited. Electrical resistance has been used in early contact studies on clean metal surfaces [62], but is limited to conducting interfaces. Recently, Enachescu et al. [63] used conductance measurements to examine adhesion in an ideally hard contact (diamond vs. tungsten carbide). In the limit of contact size below the electronic mean free path, but above that of quantized conductance, the contact area scales linearly with contact conductance. They used these measurements to demonstrate that friction was proportional to contact area, and the area vs. load data were best-fit to a DMT model. 

Before hydraulic lines or fittings are disconnected, the affected area should be cleaned with an approved dry-cleaning solvent. 

Air filters are not used on cold store coolers, since the air should be a lot cleaner and small amounts of dust will be washed off the fins by condensate or by melted frost. Air-cooled condensers are not fitted with filters, since experience shows that they would never be maintained properly. In dusty areas, condensers should be selected with wide fin spacing, so that they can be cleaned easily. 

FIG. 7 Total energy per cross-sectional area as a function of interfacial separation between Fe and A1 surfaces for the clean interface and for monolayer interfacial impurity concentrations of B, C, N, O, and S. Graph (a) is for the case where the impurity monolayer is applied to the free A1 surface prior to adhesion, while graph (h) has the impurity monolayer applied to the free Fe surface prior to adhesion. The curves fitted to the computed points are from the universal binding energy relation. (From Ref. 28. Copyright 1999 hy the American Physical Society.)... 

Where floor drainage channels are necessary they should be open if possible, shallow and easy to clean. Connections to drains should be outside areas where sensitive products are being manufactured and, where possible, drains should be avoided in areas where aseptic operations are being carried out. If this cannot be avoided, they must be fitted with effective traps, preferably with electrically operated heat-sterilizing devices. 

Sudden exposures to high concentrations, through large leaks, may lead to immediate acute effects, such as unconsciousness, burning eyes, or fits of coughing. There is rarely lasting damage to individuals if they are removed promptly from the contaminated area. In this case ready access to a clean environment is important. 

Optical detectors shall be used in more open configurations where ressure buildup due to the incipient explosion is limited. Optical etectors shall not be used where high dust concentrations limit the reliability of the suppression system. Both uv and ir detectors are available for optical detection. The use of daylight-sensitive sensors shall be avoided to avoid spurious activation. The sensor shall be mounted such that the angle of vision allows it to cover all the protected hazard area. The performance of an optical detector will also be affected by any obstacles within its vision, and this shall be overcome by the introduction of more detectors. Optical detectors shall be fitted with air shields to keep the optical lens clean. 

To 500 ml. of absolute methanol (Note 1) in a 1-1. electrolytic (tall form) beaker is added 1.1 g. (0.05 g. atom) of clean sodium metal. After solution of the sodium, 216 g. (1.0 mole) of methyl hydrogen sebacate (Note 2) is dissolved in the sodium methoxide solution. A magnetic stirring bar is placed in the beaker which is then fitted with a large neoprene stopper (Note 3) holding a platinum sheet anode, 12 cm.2 in area and two platinum sheet cathodes, approximately 5.3 cm.2 in area, spaced equidistantly on either side of the anode at a distance of approximately 1.5 cm. (Note 4). The stopper is also provided with a stoppered entry tube and an efficient reflux condenser (Note 5). 

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