Separation distance

A common approach to treating retardation in dispersion forces is to define an effective Hamaker constant that is not constant but depends on separation distance. Lxioking back at Eq. VI-22, this defines the effective Hamaker constant... 

Derive Eq. XII-18. In an experiment using hexadecane and crossed mica cylinders, the circular flat contact area is about 10 cm in diameter and the two surfaces oscillate back and forth to the extent of 1 % of their diameter per second. The separation distance is 10 A and the yield pressure of the glue-backed mica is 0.1 kg/mm. ... 

Much of tills chapter concerns ET reactions in solution. However, gas phase ET processes are well known too. See figure C3.2.1. The Tiarjioon mechanism by which halogens oxidize alkali metals is fundamentally an electron transfer reaction [2]. One might guess, from tliis simple reaction, some of tlie stmctural parameters tliat control ET rates relative electron affinities of reactants, reactant separation distance, bond lengtli changes upon oxidation/reduction, vibrational frequencies, etc. 

In Figure 6.4, the two electrodes are marked as cathode and anode, arising from the application of an external voltage between them. Before any discharge occurs, the electric-field gradient between the electrodes is uniform and is simply the applied voltage divided by the their separation distance, as shown in Figure 6.7. 

The initial election—hole separation distance, and the quantum yield, ( )q, are derived by fitting with the Onsager model. When the initial quantum yield,... 

Experimental Values of Charge-Generation Efficiencies. In this section the charge-generation efficiencies of many polymeric photoconductors are compared (Table 3). When the experimental data has been fitted to the Onsager model, the initial electron—hole separation distance,... 

For a line spark source, the flame volume is initially cylindrical with the cylinder length equal to the separation distance between the electrodes. Thus, for a cylindrical flame, = e, and the critical ignition volumes are equation 7 for a spherical flame and equation 8 for a cylindrical flame where = critical ignition volume, m /kg e = thickness of flame front, m and d = flame height, m. 

The electrostatic repulsive forces are a function of particle kinetic energy (/ T), ionic strength, zeta potential, and separation distance. The van der Waals attractive forces are a function of the Hamaker constant and separation distance. 

When the maximum dimensions of each of two plane surfaces is small relative to their center-to-center separating distance / Eq. (5-120) gives... 

Example 3 Calculation of View Factor Evaluate the view factor between two parallel circular tubes long enough compared with their diameter D or their axis-to-axis separating distance C to make the problem two-dimensional. With reference to Fig. 5-18, the crossed-strings method yields, per unit of axial length,... 

Provide safe separation distances for normal operation, maintenance, emergency egress, ergonomics... 

Ignition of flammable Provide safe separation distances release resulting in fire. Develop appropriate area electrical or explosion. classification Provide ignition source control Place ignition sources in positive pressure enclosure and buildings Provide adequate ventilation API RP500 BS 5345 BS 5958 NFPA-70 NFPA-77... 

Provide safe separation distances Install fixed fire protection and alarms, water sprays (deluge), and/or foam systems activated by flammable gas, flame, and/or smoke detection devices... 

Figure 3 A calculated reflectivity profile for a perdeuterated polystyrene film with a thickness of SO nm on a silicon substrate. The calculation was for a specimen where the interfaces between the specimen and air and the specimen and the substrate were sharp. This causes the reflectivity on average (shown by the dashed line) to decrease in proportion to k or 9. The separation distance between the minima of the oscillations diractly yields the thickness of the specimen, as shown.

The area should be at the separation distance from the property boundary, any building or fixed source of ignition quoted in Table 9.1 7. This may only be reduced if suitable fire-resisting separation is provided. 

To give additional protection from thermal radiation from any cylinder stack fire the minimum separation distance to any nearby building housing a vulnerable population should, for quantities >400 kg, be 8 m or as in Table 9.1 7, column 3, whichever is the greater. This may be reduced to those in Table 9.17, column 4, by the installation of fire-resisting separation or a fire wall. 

Prohibit all sources of ignition, including smoking, within a store or within the separation distance (exclude motor vehicles other than fork-lift trucks and those for delivery/collection from open-air stores). 

Avoid openings into buildings, cellars, or pits within 2 m or the separation distances, whichever is greater. (Any gully or drain unavoidably within 2 m should have the opening securely covered or fitted with a water seal to prevent vapour ingress.)... 

Electrical equipment suitable for a Zone 2 area (e.g. to BS 5345) and constructed to a recognized standard should be installed within the store and separation distance. Zone 2 areas are summarized in Table 9.18. 

Avoid accumulation of rubbish, small bushes, dry leaves etc. within the separation distance. Remove weeds and long grass within the separation distance and up to 3 m from cylinders. 

Cylinders on a vehicle or trailer parked overnight rate as a single stack so that the separation distance in Table 9.17, column 3, is applicable. 

Table 9.17 Recommended minimum separation distances for total storage of LPG in cylinders stack (the greater of the two distances is advised) or size of maximum...

Total quantity LPC store Size of largest stack Minimum separation distance to boundary, building or fixed ignition sources from tbe nearest cylinder (where no fire wall provided) Minimum separation distance to boundary, building or fixed ignition source from fire wall (where provided) ... 

No separation distance is required for these quantities where boundary walls and buildings are of suitable construction. 

The entire space within the building or storage area and outside any doorway, low level ventilator or other opening into the store within the separation distance set out in Table 9.1 7, column 3, up to a height of 1.5 m above ground level. 

Table 15.7 Limits on quantities of explosives permitted for carriage by rail in containers and wagons, and separation distances...

Column 1 Type of explosive Column 2 Maximum net explosive content in tonnes in any group of adjacent containers or wagons Column 3 Minimum separation distance in metres between groups of containers or wagons... 

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