Bar, pressure unit

British anti-Eewisite [2,3-dimercapto-l-propanol] benzo [a] pyrene bar (pressure unit) barrel... 

Pd = ASME Code design pressure (or maximum allowable working pressure), psi Pdo = pressure on outlet side of rupture disk, psia Pe = exit or back pressure, psia, stamped burst pressure Per = perimeter of a cross section, ft or meters Pn = Initial high pressure, mmHg Pj = maximum initial pressure at which the combustible atmosphere exists, psig P j = initial pressure of system, psia PL = initial low pressure or vacuum, mmHg Pmax =- maximum explosion pressure, bar, or other consistent pressure units... 

AVT Barg BD BDHR BF BOF BOOM BOP BS W BSI BTA Btu/lb BW BWR BX CA CANDUR CDI CFH CFR CHA CHF CHZ Cl CIP CMC CMC CMC COC All-Volatile treatment bar (pressure), gravity blowdown blowdown and heat recovery system blast furnace basic oxygen furnace boiler build, own, operate, maintain balance of plant basic sediment and water British Standards Institution benzotriazole British thermal unit(s) per pound boiler water boiling water reactor base-exchange water softener cellulose acetate Canadian deuterium reactor continuous deionization critical heat flux Code of Federal Regulations cyclohexylamine critical heat-flux carbohydrazide cast iron boiler clean-in-place carboxymethylcellulose (sodium) carboxy-methylcellulose critical miscelle concentration cycle of concentration... 

Very large LC columns up to 1.2 m in diameter have been used on occasion since the 1940s. These were low pressure units with very large packing particles and were therefore relatively slow and inefficient. The use of smaller particles and higher velocities, both requiring large column pressure differences (40-400 bar), has been a key factor in the development of modern HPLC since 1967 (Section 19.3.2.) The other two factors were improved stationary phases (Section 19.4.3) and better detectors. 

The torr is included in the table only to facilitate the transition from this familiar unit to the statutory units N m, mbar and bar. In future the pressure units tor, mm water column, mm mercury column (mm Hg), % vacuum, technical atmosphere (at), physicalatmosphene (atm), atmosphere absolute (ata), pressure above atmospheric and pressure below atmospheric may no longer be used. Reference is made to DIN 1314 in this context. 2) The unit Newton divided by square meters (N m ) is also designated as Pascal (Pa) 1 N m = 1 Pa. Newton divided by square meters or Pascal is the SI unit for the pressure of fluids. 3) 1 torr = 4/3 mbar fl torr = 1 mbar. ... 

Laboratory units can be divided into bench-scale, research-, and pilot-scale. Bench-scale units, available in sizes of 20 to 500 ml (up to 400 bar) are used for screening tests, because one can obtain a relatively fast overview of the influence of the diverse major parameters, and only small quantities of raw material are necessary. Optimization duties require research units in sizes of 2 to 10 1, and are available in the pressure range between 325 and 700 (1000) bar. Such units enable quantity- and quality analyses. An illustration of one commercially available unit is shown in Fig. 8.1-1. For scale-up purposes, pilot plants ranging from 20 to 100 1, with design pressures up to 550 (700) bar, are recommendable for use with new products. 

BAR (bar). A unit of pressure. One bar equals 100,000 newtons per square meter. 

Table 2.4 Physical and crystalline properties of naturally occurring elemental arsenic polymorphs at25°C and 1 bar pressure (Baur and Onishi, 1978 fide, 2007 Matsubara et al., 2001 O Neil et al., 2001). See the text and Appendix B for explanations of the terms and units of measure.

Table C. 1 Thermodynamic data for arsenic, its compounds, and its aqueous and gaseous species at 1 bar pressure. Note that the units of G and Hi are 1000 times larger than Si and Cpt. 1 kcal = 4.184 kj. ° C = K —273.15. (See Appendix A for other unit conversions). Phases include amorphous (am), aqueous species (aq), gas, liquid (liq), and crystalline solids (xls). 

Kp can replace K in equation (16-8). If AG° is obtained from a table based on the standard state of 1 atm, Kp will normally be correct only for P in atmospheres. If the values are for a standard state of 1 bar, then Kp will normally apply only to P in bars. When the equation shows no change in the total number of moles of gas as the reaction proceeds (e.g., N2 + O2 == 2NO), Kp will be the same, regardless of the pressure units used and will be identical with the K expressed in molar concentrations. 

One pascal corresponds to a very small pressure as compared with one atm, that is, 1 Pa = 9.86923 X 10 6 atm. The bar is another commonly used pressure unit. One bar is defined as 105 Pa and is equal to 750 torr. 

The sonic venturi can also meter the flow of liquids. This flowmeter is available in sizes from 1 to 8 in. (25 to 200 mm). Units have been built for up to 10,000 psig (690 bar) pressure services and for temperatures from cryogenic to 1,200°F (650°C). 

The illegal arguments on the left-hand side of Table 6.1 all have units and are not dimensionless. Thus P is measured in pressure units (Pa, bar, atm, Torr, mm Hg, lb in-2 etc.) and only ratios of pressures can be dimensionless and then only if their units correspond so cancel to give a dimensionless number. Similarly PIbar is legal since we imply by this that the pressure P is measured in bar and if then divided effectively by 1 bar, yields a dimensionless number (which equals the number factor by which the pressure P is greater than 1 bar). 

As shown in the previous section a common feature of all systems in the liquid state is their molar entropy of evaporation at similar particle densities at pressures with an order of magnitude of one bar. Taking this into account a reference temperature, Tr, will be selected for systems at a standard pressure, p° = 105 Pa = 1 bar, having the same molar entropy as for the pressure unit, p = 1 Pa at T = 2.98058 K. As can easily be verified, the same value of molar entropy and consequently the same degree of disorder results at p if a one hundred-fold value of the above T-value is used in Eq. (6-14). This value denoted as Tw = 298.058 K = Tr is used as the temperature reference value for the following model for diffusion coefficients. The coincidence of Tw with the standard temperature T = 298.15 K is pure chance. 

By SI definition, "normal atmosphere" is 101.325 kPa = 1.01325 x 106 Nm 2 760 mm Hg = 760 torr 1 bar. Pressure measured as a pure force per unit area is called absolute pressure a pressure difference between any two points is called differential pressure gauge pressure is pressure above normal atmospheric pressure. 

P) force per unit area. The SI unit of pressure is the pascal, defined as one newton per square meter. Other common pressure units are the atmosphere, the bar, and the Torr. 

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