Bench Height

Once the bench height has been determined, the diameter of the blast hole is next for consideration. The suggested ratio between bench height and blast hole diameter (Konya and Walter, 1990) is given by Equation (4.1) ... 

Since the benches in the quarry are usually horizontal, the computer can, via the standard deviation, determine coefficients of variation and limiting concentrations for selected areas of the deposit. From this information the bench height and bench sections can then in turn be obtained. 

The obtained results for the magnetic bench have allowed to note that defects situated at 12 mm of depth have been observed clearly. This is explained by the high power furnished by the bench, in addition its induction is double alternation rectified. Dimensions of the defect (height and width) are precisely estimated (figure 1). The defect detection at this depth is due to the application of a rectified field, so skin phenomenon is almost absent. 

The laboratory workers office space should be as close as possible to work areas and to fi equently used files. There should also be room for a typewTiter, if required. The work may be done on a separate desk or a section of desk-height work bench. 

Cabinets come in a variety of units to suit individual needs. These are then bolted together to make benches. Any combination of drawers, cupboards, and knee-hole units is possible. Some fume hoods come complete with their own base cabinets. Where desirable, desk-height units can be integrated into the system. All units come with legs which can be acijusted for an uneven floor. Standard installation leaves room behind the counters or along the middle of peninsulas for utilities. After the cabinets are installed, counter tops are put in place and bench-mounted fume hoods added. 

In an educational laboratory such overhead mounting must be planned with care. The typical work benches here are either peninsulas or islands where the utility box would go down the center with a shelf on top. The total height must be such that the instructor is able to look over the shelf in order to supervise a class. To complicate matters, there may be a waste water trough along the center of the bench which requires some free space above it. These multiple requirements present a challenge to the designer. 

The construction of sample chambers is constrained by the height and the width of the bars from the optical bench... 

Finally, the wrangle is halted. The audience in the gallery settles down. Above the level of the fury and bias, the defendants dock faces the bench. By the strange convention of juridical architecture, height stands for both despair and dispassionate judgment. 

The mill has been developed, partly at the University of Toronto, Canada1-20 21) and commercialised by General Comminution Inc. in Toronto. Capacities range from 20 kg to 10 tonnes of dry material per hour. A small laboratory pilot mill has an inside diameter of 160 mm and fits on a bench. The large, 640 mm diameter unit has external dimensions of about 2mx2mxlmin terms of height, length and width. 

These factors are introduced in the experimental plan at the bench-scale before the pilot--plant stage. On the bench-scale, glass or steel laboratory reactors of about 1 to 2 L will be used for MSSR and a 30 cm diameter and 2 m height for BSCR. 

When the tube is about to be filled it should be clamped in a vertical position at the side of the bench and at a suitable height for filling. A funnel with a short but wide stem should be inserted in the open end of the tube to assist in the filling. 

Fig. 7.3. Cathelometer. This type of cathelometer is used in routine manometry. It is light in weight and may be moved easily from one site to the next. A sturdy three-iegged platform which is the same height as the vacuum line bench may be used to bring the cathelometer to the proper height for the observation of manometers on the vacuum line.

Example 9.5 Extremely fine polonium-210 particles (0.01-p.m diameter, p = 9.4 g/cm3) are spilled on a laboratory bench. Assuming a barometric distribution is established, at what height will c/c0 = 0.1 ... 

While some glassblowers prefer to stand at the bench it is considered good practice to sit when working. Again there are many who prefer a comfortable chair with a padded seat and back rest. In general, a laboratory stool is all that is necessary. In the seated position the elbows should rest comfortably on the bench top, just in from the edge. Both feet should be on the floor. An easy elbow position is essential. Should this need a stool of such height that one s feet do not reach the floor they may be rested side by side on a stool leg brace. 

Many hours will be spent seated at the bench, so. it is important that the working position be free from discomfort. The body-weight must be evenly distributed, the feet should not dangle in mid-air, nor should the legs be crossed or stretched out under the bench in a relaxed attitude. Try a number of stools of different heights to find one that is suitable, and as a last resort alter the seat height. 

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