Humidity control device for the Buerger precession camera

AbstractThe humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, which often leads to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals on a beamline have led to this technique being increasingly adopted, as experiments become easier and more reproducible. Matching the relative humidity to the mother liquor is the first step to allow the stable mounting of a crystal. In previous work, we measured the equilibrium relative humidity for a range of concentrations of the most commonly used precipitants and showed how this related to Raoult’s law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between measured values and those predicted by theory could not be explained. Here, we have used a more precise humidity control device to determine equilibrium relative humidity points. The new results are in agreement with Raoult’s law. We also present a simple argument in statistical mechanics demonstrating that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult’s Law. The same argument can be extended to the case where solvent and solute molecules are of different size, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding samples.SynopsisThe equilibrium relative humidity values for a number of the most commonly used precipitants in biological macromolecule crystallisation have been measured using a new humidity control device. A simple argument in statistical mechanics demonstrates that the saturated vapour pressure of a solvent is proportional to its mole fraction in an ideal solution (Raoult’s Law). The same argument can be extended to the case where solvent and solute molecules are of different size.

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EXPERIMENTAL STUDY OF NATURAL GAS HUMIDITY CONTROL DEVICE

Informatyka Automatyka Pomiary w Gospodarce i Ochronie Środowiska ◽

10.35784/iapgos.2079 ◽

2020 ◽

Vol 10 (3) ◽

pp. 86-90

Author(s):

Yosyp Bilynsky ◽

Oksana Horodetska ◽

Svitlana Sirenko ◽

Dmytro Novytskyi

Keyword(s):

Natural Gas ◽

Traveling Wave ◽

Single Channel ◽

Control Device ◽

Ultrahigh Frequency ◽

Correction Factors ◽

Frequency Method ◽

Waveguide Section ◽

Humidity Control ◽

Humidity Measurement

The means of measuring humidity based on the use of the ultrahigh frequency method have been recently gaining widespread use, because of its simple, robust construction and high measuring accuracy. We used the advanced waveguide ultrahigh frequency method of measuring the moisture content of natural gas which, in contrast to the known the use of a traveling wave in a waveguide, is proposed. In this case, the interaction with waves of the ultrahigh frequency range changes the dielectric properties of the gas, and this change is registered. On the basis of an improved ultrahigh frequency method of humidity measurement, a device for natural gas humidity control using a traveling wave in a waveguide is proposed. The investigations have shown that a comparative channel increased the measurement accuracy, as a two-channel system – in contrast to a single-channel – eliminates the instability of the value of the input signal supplied to the generator. The principle of operation of a natural gas humidity control device that contains an ultrahigh frequency generator, attenuators, waveguide tees, a waveguide section for comparison, temperature sensor and pressure switches for the comparative and measuring channels, a measuring cuvette, amplifier, microprocessor, and display unit is described. A mathematical model of a natural gas humidity control device, which takes into account the values of the dielectric permittivity of the measuring gas and reference channels and contains correction factors for temperature, the use of which increases the accuracy of humidity measurement, is proposed. The lower and upper calibration points of the natural gas humidity control device are defined. The influence of correction factors for the temperature at the measurement error of the humidity is analyzed.

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A Case Study of Innovative Engineering Education System by Idea Factory (Development of Temperature-Humidity Control Device for Fiber Storage on Composites)

Journal of Engineering Education Research ◽

10.18108/jeer.2017.20.1.63 ◽

2017 ◽

Vol 20 (1) ◽

pp. 63-68

Author(s):

박수정 ◽

김윤해

Keyword(s):

Engineering Education ◽

Education System ◽

Control Device ◽

Humidity Control

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A humidity control device for ovens

Journal of Scientific Instruments ◽

10.1088/0950-7671/13/12/306 ◽

1936 ◽

Vol 13 (12) ◽

pp. 412-413

Author(s):

C T Webster

Keyword(s):

Control Device ◽

Humidity Control

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Raoult's law revisited: accurately predicting equilibrium relative humidity points for humidity control experiments

Journal of Applied Crystallography ◽

10.1107/s1600576717003636 ◽

2017 ◽

Vol 50 (2) ◽

pp. 631-638 ◽

Cited By ~ 5

Author(s):

Michael G. Bowler ◽

David R. Bowler ◽

Matthew W. Bowler

Keyword(s):

Relative Humidity ◽

Vapour Pressure ◽

Important Variable ◽

Control Device ◽

Raoult’S Law ◽

Simple Argument ◽

Acta Cryst ◽

Humidity Control ◽

Humid Atmosphere ◽

Raoult's Law

The humidity surrounding a sample is an important variable in scientific experiments. Biological samples in particular require not just a humid atmosphere but often a relative humidity (RH) that is in equilibrium with a stabilizing solution required to maintain the sample in the same state during measurements. The controlled dehydration of macromolecular crystals can lead to significant increases in crystal order, leading to higher diffraction quality. Devices that can accurately control the humidity surrounding crystals while monitoring diffraction have led to this technique being increasingly adopted, as the experiments become easier and more reproducible. Matching the RH to the mother liquor is the first step in allowing the stable mounting of a crystal. In previous work [Wheeler, Russi, Bowler & Bowler (2012). Acta Cryst. F68, 111–114], the equilibrium RHs were measured for a range of concentrations of the most commonly used precipitants in macromolecular crystallography and it was shown how these related to Raoult's law for the equilibrium vapour pressure of water above a solution. However, a discrepancy between the measured values and those predicted by theory could not be explained. Here, a more precise humidity control device has been used to determine equilibrium RH points. The new results are in agreement with Raoult's law. A simple argument in statistical mechanics is also presented, demonstrating that the equilibrium vapour pressure of a solvent is proportional to its mole fraction in an ideal solution: Raoult's law. The same argument can be extended to the case where the solvent and solute molecules are of different sizes, as is the case with polymers. The results provide a framework for the correct maintenance of the RH surrounding a sample.

Download Full-text