Draining Requirements

When removing the first manway, the following guidelines can be used  

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Designers must include all the tasks in their designs. Designs for steady state operation have been reported to lack start-up or shutdown capability. Some plant designs lacked the vents and drains required to empty, flush, and clear the equipment. 

Is a piped drain required in the suction can of vertical double case pumps Yes No... 

P047 Drain Required DRAIN c 1 1 yes (true) 0 no (false)... 

Floors must be easily cleaned and disinfected. Drains should be avoided, as these are important sources of contamination. If a drain is unavoidable because the equipment demands it, it should be equipped with a sanitary valve, preferably a type that closes automatically when the connected equipment is shut down. Such a drain requires a well-documented disinfection procedure. 

Worcester series. Red silt loam (or silty clay loam) formed from Keuper Marl and found in the East and West Midlands and in the south west. They are slow-draining, require subsoihng regularly and are best suited to grass and cereals. 

Batteries designed for operation at low current drain require modification of the structure to prevent internal electrical discharge paths from forming from the conductive materials in both anode and cathode. After partial discharge, metallic mercury globules are particularly troublesome in this respect. The problem can be minimized by the use of silver powder in the cathode. 

Table 14.23 lists the characteristics of the cylindrical Li/FeS2 AA-size battery that is currently available commercially. This battery has better high-drain and low-temperature performance than the conventional zinc cells and is intended to be used in applications that have a high current drain requirement, such as cameras, computers, and cellular phones. An example of the advantage of the lithium cell, compared to the Zn/alkaline/Mn02 battery is shown in Fig. 14.85, which plots the number of flashes obtained with an autoflash SLR camera. The lithium battery outperforms the alkaline battery by delivering more flashes with a more rapid recycle time. See Fig. 6.12 for additional comparative data on the use of several battery types in photoflash use. 

Spirally Wound Cells. Cylindrical batteries in C and D sizes have been designed with spirally wound electrodes to meet higher drain requirements. Figure 14.93 shows the discharge performance of a Li/CuO D-size battery at various temperatures and at relatively low and high discharge rates. 

Using thin-film technology, sohd state microbatteries are compatible with microelectronics. One can in principle prepare an on-chip microbattery capable of maintaining its memory during a power outage. The combination of the thin-film configuration and the low current drain requirements (1 to 10 riA cm for a C-MOS memory) allows for the use of electrolytes with much lower conductivities than are necessary in the Na/S cell apphcations, for example. 

In general, IdR2,d is the potential drop at the drain required to drive an injection current 7d across the contact. In Fig. 7 calculated transfer characteristics for different Rp d (substitute 2 —> p) are depicted [43]. The charge carrier species 1 and 2 in Eq. (8) correspond again to electrons and holes, respectively. While a contact resistance of OQ is essentially an ohmic contact, an increase in Rp can be seen as an increase in the hole injection barrier at the drain contact, i.e., by the choice of another metal. The contact resistance acts twofold on the transfer characteristic. On one hand the hindered injection of the complementary charge carriers results in a delayed onset of the ambipolar behavior. On the other hand, the characteristic in the ambipolar region is influenced by the reduced injection rate at the drain contact itself. Apparently, for a very high contact resistance the ambipolar behavior is fully eliminated and the device turns to an essentially unipolar behavior. 

The top of the bench should always be kept clean and dry this can easily be done if a wet and a dry rag are kept at hand. Apparatus not immediately required (a) should be kept as far as possible in a cupboard beneath the bench if it must be placed on the bench, it should be arranged in a neat and orderly manner. All apparatus should be washed immediately after use and placed in a position to drain at the first opportunity, the apparatus should be dried. It must be emphasised that as a general rule a deposit of dirt or tar is more easily removed when it is freshly formed a suitable cleaning agent can usually be found while one still remembers the nature of the material or the circumstances attending its formation. It is hardly necessary to add that sohd waste and filter papers must not be thrown into the sink, and that all operations requiring the handhng of unpleasant and noxious materials sliould be carried out in the fume cupboard ( hood ). 

Dissolve 5 g. of phenol in 75 ml. of 10 per cent, sodium hydroxide solution contained in a wide-mouthed reagent bottle or conical flask of about 200 ml. capacity. Add 11 g. (9 ml.) of redistilled benzoyl chloride, cork the vessel securely, and shake the mixture vigorously for 15-20 minutes. At the end of this period the reaction is usually practically complete and a sohd product is obtained. Filter oflf the soUd ester with suction, break up any lumps on the filter, wash thoroughly with water and drain well. RecrystaUise the crude ester from rectified (or methylated) spirit use a quantity of hot solvent approximately twice the minimum volume required for complete solution in order to ensure that the ester does not separate until the temperature of the solution has fallen below the melting point of phenyl benzoate. Filter the hot solution, if necessary, through a hot water funnel or through a Buchner funnel preheated by the filtration of some boiling solvent. Colourless crystals of phenyl benzoate, m.p. 69°, are thus obtained. The yield is 8 g. 

In Chap. 9 we shall examine the flow of a solution through a capillary tube. The rate of volume delivery in that case is given by Poiseuille s law [Eq. (9.29)], which states that the time required for a constant volume of liquid to drain out of the capillary is proportional to r jp. Accordingly, the viscosity is proportional to the product pt, and when the delivery times for two liquids are compared in the same capillary. 

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