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Force Gauges with Manometric Liquids
Published in Igor Bello, Vacuum and Ultravacuum, 2017
Herbert G. McLeod reported the design and principle of the McLeod gauge653,654 in 1874. McLeod received the credit for the development of this gauge. The McLeod gauge uses the compression principle based on Boyle’s law to measure pressure below 100 Pa (~1 Torr). However, the compression principle was also used by Thomas Telford MacNeil655 in his barometer earlier (1870). The same principle was employed by Arago and Dulong in their studies of steam pressure in the period 1825–1829. The question if McLeod knew about these and other devices is unclear. The earlier constructions that used the compression effect are also discussed by Thomas and Leyniers.656 Nevertheless, the introduction of McLeod gauges into practice led to routine measurements of pressures in the range of 100–10−4Pa, particularly at the beginning of the last century.
Pressure in fluids
Published in John Bird, Science and Mathematics for Engineering, 2019
The McLeod* gauge is normally regarded as a standard and is used to calibrate other forms of vacuum gauges. The basic principle of this gauge is that it takes a known volume of gas at a pressure so low that it cannot be measured, then compresses the gas in a known ratio until the pressure becomes large enough to be measured by an ordinary manometer. This device is used to measure low pressures, often in the range 10−6 to 1.0 mm of mercury. A disadvantage of the McLeod gauge is that it does not give a continuous reading of pressure and is not suitable for registering rapid variations in pressure.
Pressure Measurement Techniques
Published in Ethirajan Rathakrishnan, Instrumentation, Measurements, and Experiments in Fluids, 2020
The McLeod gauge is used as a standard for measuring low vacuum pressures. It is basically a mercury manometer. A typical McLeod gauge is shown schematically in Figure 7.40. The measuring procedure of a McLeod gauge is as follows. The mercury reservoir is lowered until the mercury column drops below the opening O. Now the bulb B and the capillary C are at the same pressure as the vacuum space p. The reservoir is raised until the mercury fills the bulb and rises in the capillary up to a level at which the mercury in the reference capillary is at zero level marked on it. Let the volume of the capillary per unit length be “a.”
Model development, simulation and parameter estimation for pervaporative separation of benzene from model pyrolysis gasoline using insitu(nano)silver/polyvinyl alcohol membrane
Published in Chemical Engineering Communications, 2023
Monalisha Samanta, Pramita Sen, Dipa Biswas, Debarati Mitra
PV set up (Samanta et al. 2021a, 2021b) was used to carry out the pervaporative debenzenation of model Py Gas (benzene/1-octene mixture) utilizing the insitu(nano)Ag/PVA membrane. The PV setup comprised of a permeation cell (stainless steel) fitted with a thermostat, vacuum pump equipped with a Mcleod gauge (for monitoring the downstream pressure) and cold trap. The permeation cell has a feed agitator with a digital display, a band heater, and a porous metal support where the chosen membrane was mounted. The cold trap of liquid nitrogen-filled cryogenic container was used to capture and condense the vapor permeate. The membrane’s functional area was 38.32 × 10−4 m2. The working temperature was varied between 303 K–343 K, the downstream pressure was adjusted between 0.5 mm Hg–1.5 mm Hg and the mole fraction of benzene in feed mixture (benzene/1-octene) was varied from 0.3 to 0.7. Following the PV experiments, the quantity of 1-octene and benzene in the permeates and retentates were determined using gas chromatography (Samanta et al. 2021a, 2021b). Flux, separation factor, and PSI are typical performance parameters used to describe the PV separation process.
Studies on sorption kinetics and sorption isotherm for pervaporative separation of benzene from model pyrolysis gasoline using insitu nano silver/polyvinyl alcohol membrane
Published in Journal of Environmental Science and Health, Part A, 2021
Monalisha Samanta, Sayan Roychowdhury, Debarati Mitra
The pervaporative separation of benzene from model Py gas (benzene/1-octene mixture) applying the insitu nano Ag/PVA membrane was performed using a PV set up (Fig. 1).[2] The PV set up is furnished with a permeation cell, cold trap, Mcleod gauge and vacuum pump. This permeation cell is made of stainless steel. It is equipped with a band heater, feed agitator and a porous metal plate where the insitu nano Ag/PVA membrane was placed. The band heater is coupled with a temperature sensor which was used for controlling the operating temperature. The vacuum pump is connected to a Mcleod gauge for measuring the downstream pressure. The liquid nitrogen assisted cold trap was used for collecting the condensed permeate. The practical area of the membrane was 38.32 × 10−4 m2. The operational temperature was varied from 303 K to 343 K with a constant downstream pressure of 1 mm Hg. The feed (benzene/1-octene mixture) composition was varied from 30 vol% to 70 vol% of benzene. The PV experiment was not continued above 343 K due to enhanced evaporation loss. After PV experiment, the amount of benzene and 1-octene present in permeates and retentates were analyzed by Gas Chromatography. The performance of PV separation process is generally represented by the parameters like flux, separation factor and Pervaporation Separation Index. The following Eqs. (11)–(13) were used to calculate the permeation flux, separation factor and Pervaporation separation index respectively.[24,35]