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Absolute vacuum mercury

Absolute zero pressure is absolute vacuum. This is 0 psia, also known as 29.92 inches of mercury below atmospheric pressure, or 33.931 feet of water below atmospheric, all referenced at sea level,... [Pg.53]

When a vacuum is applied to the apparatus, reduced pressure forces the liquid or liquids to volatize much more readily. As a result, less heat is needed to force the liquid or liquids into the gas phase. For example, at sea level (atmospheric pressure), water boils at 100 Celsius, but at 15,000 feet water boils at 92 Celsius. It is possible to reduce the pressure of a distillation apparatus to a point where water boils at 50 Celsius. Nevertheless, when using laboratory glassware, the strength of the vacuum is limited. An absolute vacuum using lab glass is impossible due to outside forces. If we applied an absolute vacuum to a glass distillation apparatus, it would implode. Vacuums as low as 0.01 millimeters of mercury are possible using thick walled stainless metal apparatus. [Pg.23]

An absolute vacuum (0 N/m absolute) exists in the top of a mercury barometer, where the force of the atmospheric air is equalled by the force exerted by the height of the column of mercury in the barometer tube. [Pg.488]

Closed U tubes (Fig. 10-10) using mercuiy as the manometric fluid serve to measure direclly the absolute pressure p of a fluid, provided that the space between the closed end and the mercury is substantially a perfect vacuum. [Pg.890]

If pressure is expressed as inches of mercury vacuum, the reading of the local barometer (or a reference barometer) is necessary to establish the absolute sucdon pressure, or pressure in the vacuum system. [Pg.348]

When used as a vacuum pump, these single-stage units can pull vacuum down to 27 in. of mercury vacuum (not absolute) and handle approximately 1,800 ft /min. As two-stage vacuum pumps they can pull vacuum to 29.97 in. mercury (see Chapter 6, V. 1 of this series) with about 2,000 cfm at high vacuum. [Pg.528]

Empty space in which there are no atoms or molecules. A perfect vacuum cannot be attained in practice and the term denotes a space containing air or other gas at a very low pressure. In industry vacuum is measured in inches of mercury (in Hg) ranging from 0 in at atmospheric pressure to around 30 in at zero absolute pressure. Vacuum Extrusion... [Pg.69]

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. ... [Pg.147]

Diffusion pumps operate at very low pressures. The ultimate vacuum attainable depends somewhat upon the vapor pressure of the pump liquid at the temperature of the condensing surfaces. By providing a cold trap between the diffusion pump and the region being evacuated, pressures as low as 10" mmHg absolute are achieved in this manner. Liquids used for diffusion pumps are mercury and oils of low vapor pressure. Silicone oils have excellent characteristics for this... [Pg.58]

Vacuum pump capable of maintaining a pressure (absolute) of at least 5mm of mercury... [Pg.40]

Vacuum distillation was relatively new in 1925. In fact, commercial distillation at 300 mm. of mercury absolute pressure was rather exuberantly termed high vacuum. Some batch horizontal shell stills were being utilized in vacuum distillation to produce lube oils, but extensive development in this field occurred later. [Pg.202]

Follow the procedure described in Method 101.5 for the determination of the percentage moisture and volatile in the explosive. However, in this determination heat for 6 hours in a vacuum oven at a temperature of 55° 2°C. and a pressure (absolute) of 80mm 10mm of mercury instead of four (4) hours in an oven at 100° 5°C. and atmospheric pressure. [Pg.287]

All these complications can be avoided when making field measurements by using the vacuum manometer shown in Fig. 6.6. The difference between the two mercury levels is the absolutely correct, inches of mercury absolute pressure, or millimeters of mercury (mm Hg). [Pg.65]

We have discussed the American system inches of mercury (in Hg) in Chap. 6, How Instruments Work. Of more immediate interest is Table 16.1. To do any sort of vacuum calculation, we need to convert to the absolute system, in millimeters of mercury (mm Hg). Unfortunately, we also need to correct measurements made with an American-type, (in Hg) vacuum gauge, for atmospheric pressure. You can interpolate between the two sets of data in Table 16.1, to correct for almost the entire range of typical atmospheric pressures. [Pg.188]

This residue is further heated and introduced into a vacuum column operated at an absolute pressure of about 50 millimeters of mercury, a vacuum maintained by the use of steam ejectors. A flash separation is made to produce heavy gas oil and nondistillable pitch. [Pg.1256]

Subatmospheric pressure usually is expressed in reference to perfect vacuum or absolute zero pressure, lake absolute zero temperature (the concept is analogous), absolute zero pressure cannot be achieved, but it does provide a convenient reference datum. Standard atmospheric pressure is 14.695 psi absolute, 30 inches of mercury absolute, or 760 mmHg of density 13.595 g/cm3 where acceleration due to gravity is g = 980.665 emir. ] mmHg. which equals 1 torr. is the most commonly used unit of absolute pressure. Derived units, the million or micrometer, representing 1/1000 of 1 mmHg or 1 torr, are also used for subtorr pressures. [Pg.1663]

In the MKS system of units, standard atmospheric pressure is 750 torr and is expressed as 100,000 Pa (N/m2) or 100 kPa. This means that 1 Pa is equivalent to 7.5 millitorr (1 torr = 133.3 pascal). Vacuum, usually expressed in inches of mercury, is the depression of pressure below the atmospheric level, with absolute zero pressure corresponding to a vacuum of 30 inches of mercuiy. [Pg.1663]

The freezer operates at 3 mm. of mercury absolute pressure and vacuum tightness is essential to its successful operation. [Pg.100]


See other pages where Absolute vacuum mercury is mentioned: [Pg.284]    [Pg.224]    [Pg.284]    [Pg.224]    [Pg.155]    [Pg.394]    [Pg.155]    [Pg.394]    [Pg.511]    [Pg.20]    [Pg.217]    [Pg.76]    [Pg.216]    [Pg.171]    [Pg.526]    [Pg.70]    [Pg.79]    [Pg.147]    [Pg.213]    [Pg.37]    [Pg.52]    [Pg.202]    [Pg.209]    [Pg.65]    [Pg.683]    [Pg.1661]    [Pg.190]    [Pg.290]   


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Vacuum Absolute

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