GB788538A - Improvements in or relating to heat-conduction manometers - Google Patents
Improvements in or relating to heat-conduction manometersInfo
- Publication number
- GB788538A GB788538A GB12001/54A GB1200154A GB788538A GB 788538 A GB788538 A GB 788538A GB 12001/54 A GB12001/54 A GB 12001/54A GB 1200154 A GB1200154 A GB 1200154A GB 788538 A GB788538 A GB 788538A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bridge
- chamber
- temperature
- casing
- heat conduction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
- G01L21/00—Vacuum gauges
- G01L21/10—Vacuum gauges by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured
- G01L21/12—Vacuum gauges by measuring variations in the heat conductivity of the medium, the pressure of which is to be measured measuring changes in electric resistance of measuring members, e.g. of filaments; Vacuum gauges of the Pirani type
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Fluid Pressure (AREA)
Abstract
788,538. Heat conduction manometers. HERAEUS GES., W. C. April 26, 1954 [April 25, 1953; Nov. 27, 1953], No. 12001/54. Class 40 (1). In a heat conduction manometer comprising a casing 7 containing a sealed measuring chamber 8 communicating only with the pressure chamber and a similar reference chamber 9 containing gas at constant pressure, the chambers each contain a small semi-conductor bead supported by thin electrodes. The beads 1a, 1b form the measuring and reference arms respectively of a Wheatstone bridge which is provided with a positive temperature coefficient resistor 20 in parallel with the bridge instrument to compensate for changes in ambient temperature. Through each of electrodes 2a, 2b, which are preferably of Pt or Pt alloy not more than 25 thick and circa 25 to 50 mm. long, heat conduction is less than 4 x 10<SP>-7</SP> cols./‹ C. temperature difference between its ends, and thus no greater than the heat loss through the gas the variations of which with pressure make the measurement possible. The casing 7, e.g. of brass or Cu which may be water cooled to maintain its temperature constant, is fixed to a flange 6 having a hole communicating with vacuum chamber 23. To stop bead poisoning and electrode corrosion any vapours present in the chamber are condensed on cooled baffles in the communication hole. The other bridge resistors may be external to or contained within the casing 7. Compensation for variations in sensitivity and of the zero point with such changes in ambient temperature as may occur may be effected by placing positive temperature coefficient resistors, e.g. 18 and 19, in the other bridge arms in series with the normal balancing resistors 14, 15 which may also have positive temperature coefficients and making one, 18, adjustable; by a temperature sensitive resistor 22 in series with the bridge instrument; by a negative temperature coefficient resistor 21 in the supply line of the bridge; or as shown by a combination of all these methods. In an alternative arrangement, the bridge instrument is replaced by an amplifier to permit of indication at a remote point.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE788538X | 1953-04-25 |
Publications (1)
Publication Number | Publication Date |
---|---|
GB788538A true GB788538A (en) | 1958-01-02 |
Family
ID=6699481
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB12001/54A Expired GB788538A (en) | 1953-04-25 | 1954-04-26 | Improvements in or relating to heat-conduction manometers |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB788538A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3230405A1 (en) * | 1981-08-28 | 1983-03-10 | Boc Ltd., London | GAS PRESSURE MEASURING CIRCUIT |
-
1954
- 1954-04-26 GB GB12001/54A patent/GB788538A/en not_active Expired
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3230405A1 (en) * | 1981-08-28 | 1983-03-10 | Boc Ltd., London | GAS PRESSURE MEASURING CIRCUIT |
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