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McLeod gage

The McLeod gage is shown in Fig. 1.26. By rising the mercury reservoir, the gas in the volume V at the pressure p to be measured is trapped in the bulb B. [Pg.27]

A further rising of the reservoir causes a compression of the gas in the capillary C (closed). Capillary D is open and connected to the vacuum system. The difference Ah between the two mercury heights corresponds to a pressure difference Ap = pg-Ah (Ah in mm gives numerically Ap in torr) p is the density of mercury. If the compression of the gas in B and C is isothermal, we can write  [Pg.27]

The McLeod gage is a primary vacuometer moreover its readings are independent of the type of gas, except condensable vapours. It covers a wide range of pressures with a good accuracy ( 10-4 torr around 0.1 torr, 2 x 1CL7 torr around 1CL6 torr) [13]. [Pg.27]

The main drawback is represented by the fact that a continuous monitoring of the pressure is impossible. Bakeable McLeod gages have been built [14]. [Pg.27]

The correct operation of the gage for accurate measurements is discussed in ref. [15]. [Pg.27]


The pressure of gas in the source chamber was determined from the pressure in the gas reservoir (measured with a McLeod gage) by using Dushman s (11) relations for viscous and molecular flow in the higher and lower ranges of pressure, respectively. [Pg.201]

Figure 15 gives a diagrammatic representation of a volumetric line which is used in connection with a high-temperature Calvet microcalorimeter 67). Other volumetric lines which have been described present the same general features (15, 68). In the case of corrosive gases or vapors, metallic systems may be used 69). In all cases, a sampling system (A in Fig. 15) permits the introduction of a small quantity of gas (or vapor) in a calibrated part of the volumetric line (between stopcocks Ri and Ro in Fig. 15) where its pressure Pi is measured (by means of the McLeod gage B in Fig. 15). The gas is then allowed to contact the adsorbent placed in the calorimeter cell C (by opening stopcock Ro in Fig. 15). The heat evolution is recorded and when it has come to completion, the final equi-... Figure 15 gives a diagrammatic representation of a volumetric line which is used in connection with a high-temperature Calvet microcalorimeter 67). Other volumetric lines which have been described present the same general features (15, 68). In the case of corrosive gases or vapors, metallic systems may be used 69). In all cases, a sampling system (A in Fig. 15) permits the introduction of a small quantity of gas (or vapor) in a calibrated part of the volumetric line (between stopcocks Ri and Ro in Fig. 15) where its pressure Pi is measured (by means of the McLeod gage B in Fig. 15). The gas is then allowed to contact the adsorbent placed in the calorimeter cell C (by opening stopcock Ro in Fig. 15). The heat evolution is recorded and when it has come to completion, the final equi-...
Before each experiment the catalyst was treated with pure 02 at 1 atm at 500°C and evacuated at the same temperature until a flat vacuum in a McLeod gage was obtained. [Pg.551]

MCLEOD GAGE. A liquid-level vacuum gage in which a known volume of gas. at the pressure to he measured, is compressed by the movement of a liquid column to a much smaller known volume. a> which the resulting higher pressure is measured,... [Pg.975]

Measurement of pressure. The McLeod gage is used in two ways to measure the pressure. The first method is the direct measurement of the pressure. A large McLeod gage is used and pressures of 1 X 10-6 mm. of mercury can be estimated. However, pressure readings in this low range are only approximately correct. [Pg.142]

McLeod gages, we propose to use the reactivity of zirconium as a means to estimate the true pressures within the tube. We call this method the measurement of the apparent pressure. Kinetic theory allows one to formulate an expression for the weight gain of a sample of zirconium of given surface, as a function of the temperature, pressure, molecular weight of the reacting gases, and the efficiency of the surface reaction. [Pg.144]

It is important to note that although water vapor is undoubtedly given off during the prolonged heating of the furnace tube, this effect will not influence these measurements since the water vapor is removed by the liquid nitrogen traps and also is not measured by the McLeod gage. [Pg.149]

The flow of gas was controlled with mercury cutoffs. The pertinent volumes of the apparatus were determined by expansion of argon or helium from the calibrated volume of the McLeod gage and the pressure differences were observed with a cathetometer. The reproducibility of the McLeod gage measurements was 1% or better in the pressure range used in these measurements. [Pg.151]

The typical rate curve shown in Figure 3 was observed for nitrogen adsorbed on the diamond dust at 90.1° K. The points in circles are based on McLeod gage readings and the balance of the curve was recorded from the thermocouple gage data. A steady-state surface coverage (0) of 0.055 (10.1-micron pressure) was realized after only about 200 minutes. All pressure measurements have been corrected for thermomolecular diffusion. [Pg.152]

The water was purified by a vacuum distillation from alkaline potassium permanganate solution, followed by repeated vacuum sublimation from ice until the vapor from the water showed no residual permanent gas in a McLeod gage. [Pg.365]

Pressure in the volumetric apparatus was measured by a McLeod gage and by a wide-bore (30-mm.) mercury manometer. Pressures measured with the McLeod gage were corrected for capillary depression of the mercury meniscus. Pressure in the gravimetric apparatus was controlled by regulation of the tempera-... [Pg.365]

Thermal vacuum sensors, complete system with readout. 550 McLeod gage, tilting type, 315. piston type 1100. [Pg.814]

McLeod gage for accurate determination of system pressure of 0.01 micron to... [Pg.254]


See other pages where McLeod gage is mentioned: [Pg.141]    [Pg.123]    [Pg.6]    [Pg.42]    [Pg.42]    [Pg.288]    [Pg.166]    [Pg.54]    [Pg.60]    [Pg.66]    [Pg.142]    [Pg.143]    [Pg.144]    [Pg.145]    [Pg.162]    [Pg.269]    [Pg.89]    [Pg.73]    [Pg.27]    [Pg.27]    [Pg.370]    [Pg.117]    [Pg.143]    [Pg.330]    [Pg.38]    [Pg.889]    [Pg.254]    [Pg.426]    [Pg.165]    [Pg.123]   
See also in sourсe #XX -- [ Pg.975 ]

See also in sourсe #XX -- [ Pg.142 ]




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