Hand centrifuge

A cyUndrical or, preferably, a pear-shaped separatory funnel (Fig. II, 1, 5, e and d) of 10-15 ml. capacity is usually employed for the separation of immiscible liquids. For separations on a smaller scale, a dropper pipette may be used the upper layer is best removed with a bent pipette as in Fig. XII, 1,3. For liquids which tend to emulsify, centrifugation (a hand centrifuge is satisfactory) will usually produce a clean line of demarcation between two immiscible liquids. 

Small amounts of precipitates which are difficult to filter are conveniently and rapidly separated by means of a small hand centrifuge. 

It is supplied with a dual purpose head. The buckets can either swing out to the horizontal position or, by means of a rubber adapter, the buckets can be held at a fixed angle of 45° (M.S.E.) or 51° (International) in the latter case, the instrument acts as an angle centrifuge. This is an alternative to the hand centrifuge. 

A. A small 2-tube hand centrifuge with protecting bowl and cover (Fig. 

Cytoplasmic extracts have been made from immature oocytes, either unactivated or artificially activated (Longo et aL, 1994). Ovaries are dissected from ripe females and incubated in seawater to release germinal vesicle (GV)-stage oocytes. Oocytes are washed three times in seawater by suspension and spinning in a hand centrifuge. 

Sodium polyacrylate was put in a tea bag of polyester nonwoven fabric and dipped into distilled water or solutions. The tea bags were centrifuged by a hand centrifuge as soon as possible, then weighed at intervals of 20-30 sec. 

In equation 6, characterizes the settling behavior of the soHd particles or Hquid drops in the suspension, whereas the second part of the right-hand side refers to speed and size of the centrifuge and is expressed by the capacity factor Z g. For a bottle centrifuge, it takes the following form ... 

In general, overall efficiencies of positive-displacement pumps are higher than those of centrifugal equipment because internal losses are minimized. On the other hand, the flexibihty of each piece of eqmp-ment in handling a wide range of capacities is somewhat limited. 

More detailea descriptions of small-scale sedimentation and filtration tests are presented in other parts of this section. Interpretation of the results and their conversion into preliminary estimates of such quantities as thickener size, centrifuge capacity, filter area, sludge density, cake diyness, and wash requirements also are discussed. Both the tests and the data treatment must be in experienced hands if error is to be avoided. 

The centrifugal force produced increases the impeller static pressure [the first term of the right-hand side of Eq. (9.79)] and reduces the relative velocity U2 To increase the static pressure by a change in the relative velocity, the following relationship is necessary ... 

For general service the average centrifugal pump should lift about 15 feet of water on its suction side. However, since each process situation is different, it is not sufficient to assume that a particular pump wll perform the needed suction lift. Actually, certain styles or models of a manufacturer s pumps are often specially adapted to high lift conditions. On the other hand it is unnecessary to select a high lift pump when pressure head or flooded suction conditions prevail. Proper evaluation of suction lift conditions cannot be over emphasized. 

Tumbling and centrifuging are batch processes, but all the others can be included in a continuous line process and, for suitable articles, the process can be fully automated. If the shape of the articles is unsuitable, some kind of hand spraying is usually selected. 

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