High pressure float

On a single-evaporator flooded system, a float valve can be fitted which will pass any drained liquid from the condenser direct to the evaporator. The action is the same as that of a steam trap. The float chamber is at condenser pressure and the control is termed a high-pressure float (Figure 8.3). 

High-pressure float valves plus handset throttle valves for some flooded and low-pressure receiver circuits. 

The range of a meter can be increased by the use of floats of different densities, a given float covering a flowrate range of about 10 1. For high pressure work the glass tube is replaced by a metal tube. When a metal tube is used or when the liquid is very dark or dirty an external indicator is required. 

By putting the system into a high pressure bomb (36) the magnetic system can be used to measure the densities of aqueous solutions over a wide pressure range with a precision of 11 ppm. We presently are developing a magnetic float system that can be used to measure the densities at low pressures to high temperatures (200°C). 

C. High-Pressure PVT Properties. Three methods are presently being used to measure the high-pressure PVT properties of electrolyte solutions volumetric methods, (26,32,106) high pressure magnetic float systems, (36,107,108) and high pressure speed of sound systems (109,110,111,112). I will not attempt to review all the modifications made to these systems. 

The major difficulties we have had with the high pressure magnetic system is that the floats easily break due to pressure shocks. This greatly disturbs one who has spent many hours calibrating the float in water at various pressures. 

Putting high-pressure water in cokers through a gravity separator to remove floating oil and settleable coke fines. 

In accordance with the Clapeyron equation and Le Chatelier s principle, the more highly ordered (low-entropy) phases tend to lie further to the left (at lower 7), whereas the higher-density phases tend to lie further upward (at higher 7). The mnemonic (7.32) allows us to anticipate the relative densities of adjacent phases. From the slope, for example, of the ice II-ice III coexistence line (which tilts forward to cover ice III), we can expect that ice II is denser than ice III (pn > pm). Similarly, from the forward slopes of the liquid coexistence lines with the high-pressure ices II, V, and VI, we can expect that cubes of ice II, ice V, and ice VI would all sink in a glass of water, whereas ice I floats (in accord with the backward tilt of its phase boundary). Many such inferences can be drawn from the slopes of the various phase boundaries in Fig. 7.3, all consistent with the measured phase densities Pphase (in gL 1), namely,... 

From the slopes of the phase boundaries, one can judge [using the Clapeyron mnemonic (7.32)] that pSoiid > Pi, Pii (i.e., a high-pressure ice cube of frozen helium will sink in either He-I or He-II) and that pn> Pi (i.e., the low-T He-II superfluid floats on the high-T He-I normal fluid). One can also judge from its placement at lower T that He-II is more highly ordered than He-I (5n < Si), despite its superfluid proclivities. 

Water is highly unusual in that the density of water is greater than that of ice. We know that from a common observation ice floats on water. Therefore, at the melting point, the molar volume of liquid water is less than that of ice. As a result, high pressures can encourage ice to melt at a lower temperature, and the melting point of water decreases as the pressure is increased (see Section 5.14). 

Floats are simple, reliable and rugged. They are suitable for use at high pressures and temperatures and in the presence of foams. If constructed of suitable materials, they can be employed in aggressive environments and for liquids with densities as low as 300 kg/m3. When used in the level limit alarm mode, float switches can detect variations in level down to about 2 mm. However, as they are mechanical devices, floats can suffer from jamming, fouling by the material being measured, and general wear and tear. 

Fig. 13f shows a silicone rubber float and through hole, made by molding so as to fit precisely into the hole [34]. This structure is suitable for the high pressure micropump. The size and characteristics are summarized in Table 2. 

Wire-guided float detector installation for high-pressure tanks. 

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