TITLE

Simple and reliable system for gas flow regulation and measurement

AUTHOR(S)
Sanders, William A.; Bogan, Denis J.; Hand, Clifford W.
PUB. DATE
December 1986
SOURCE
Review of Scientific Instruments;Dec1986, Vol. 57 Issue 12, p3059
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
An automatic regulation and measurement system for the delivery of gases at flow rates from about 0.01 to 1 cm³ (STP)/s is described. Flow measurement is based on the familiar direct method of determining pressure drop per unit time in a calibrated volume. The regulation and measurement functions are accomplished by simple electronic circuits. Pressure drop from the primary gas supply to the delivery point occurs in two stages. In the first stage, gas is admitted to the calibrated volume by a solenoid valve that can be opened for times as short as 10[sup -3] s. In the second stage the gas flows through a needle valve to the delivery point. The pressure in the calibrated volume is measured by a transducer. The circuit reads the transducer output and regulates the pressure by controlling the frequency and duration of the solenoid valve opening. The fluctuations in delivered gas flow are typically ±0.5%, and could be made much smaller with modest effort. This system has several advantages over commercial "mass flow meters." The relative (as opposed to absolute) error is constant. A single measurement of the "calibrated" volume suffices to calibrate the system for all gases. The gas is not exposed to heated filaments or thermistors.
ACCESSION #
9781959

 

Related Articles

  • In situ stress measurement apparatus for liquid applied coatings. Payne, Jason A.; McCormik, Alon V.; Francis, Lorraine F. // Review of Scientific Instruments;Dec1997, Vol. 68 Issue 12, p4564 

    Describes an apparatus for measuring stress development in polymer and ceramic coatings. Combination of the coating, processing and stress measurement steps; Study on the effects of processing variables; Report on the results for polyisobutyl methacrylate.

  • Distance mearsurement method using the two intermode beat frequencies of a three-longitudinal... Eom, Ick-Jae; Kyung-Chan Kim; Suh, Ho-Sung // Review of Scientific Instruments;Dec1997, Vol. 68 Issue 12, p4612 

    Reports on distance measurement method using the two intermode beat frequencies of a three-longitudinal mode He-Ne laser. Use of the stabilized laser as a laser source for a distance meter; Resolution of the distance meter.

  • Camera length and field of view in Makyoh-topography instruments. Riesz, Ferenc // Review of Scientific Instruments;Feb2001, Vol. 72 Issue 2, p1591 

    Makyoh topography is an optical method for the study of the large-scale morphology of mirror-like surfaces. Formulas are derived for the two basic parameters, the camera length and the field of view of Makyoh instruments. The relation between these parameters and the sensitivity are established....

  • Measurement of fast surface photovoltage relaxation. Hlavka, J.; Svehla, R. // Review of Scientific Instruments;Jul96, Vol. 67 Issue 7, p2588 

    Presents a version of the measuring circuit which allows for the measurement of fast surface photovoltage relaxation in a simple way. Analysis of the measuring circuit; Components of the apparatus.

  • Diamond anvil cell for cryogenic temperature with optical measurement system. Kawamura, Haruki; Tachikawa, Kyoji; Shimomura, Osamu // Review of Scientific Instruments;Oct85, Vol. 56 Issue 10, p1903 

    A diamond anvil type high-pressure cell for a low-temperature experiment with an optical system is described. The diamond anvil type pressure cell is actuated by helium gas in the cryostat at low temperatures. The optical system is for the pressure calibration at low temperatures by the use of...

  • Surface and Volume Resistivity Meter.  // Physics Today;Oct90, Vol. 43 Issue 10, p106 

    Reviews the Hiresta IP, a direct-reading line of high-resistance surface and volume-resistivity meters from Optical Associates.

  • Device for measuring the force and separation between two surfaces down to molecular separations. Parker, J. L.; Christenson, H. K.; Ninham, B. W. // Review of Scientific Instruments;Oct89, Vol. 60 Issue 10, p3135 

    We present an apparatus for measuring the force as a function of distance between surfaces at separations down to the order of molecular dimensions. The device is a simplified yet improved version of the surface force apparatus first developed by Israelachvili and Adams [J. Chem. Soc. Faraday...

  • Response compensation of thermistors: Frequency response and identification of thermal time constant. Tagawa, M.; Kato, K.; Ohta, Y. // Review of Scientific Instruments;Mar2003, Vol. 74 Issue 3, p1350 

    The purpose of this study is to improve the accuracy of general-purpose temperature sensors (commercially available thermistors) in fluctuating temperature measurement and to extend their applicability. First, heat transfer models reflecting the internal structures of plate-type and spherical...

  • A highly automatic measurement system for three orthogonal magnetic moments of a permanent... Hwang, C.S.; Shuting Yeh; Teng, P.K.; Uen, T.M. // Review of Scientific Instruments;May96, Vol. 67 Issue 5, p1741 

    Reports on the design and construction of a highly automatic system with a three-angle rotation mechanism to measure several thousand permanent magnet blocks. Algorithm for data analysis; Measurement system; System calibration and precision; Accuracy of the system.

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics