Improvements in or relating to sensitive manometers

Abstract

Abstract 653,536. Differential - pressure meters. BRITISH IRON & STEEL RESEARCH ASSOCIATION. March 19, 1948, No. 8244. [Class 40 (i)] [Also in Group XL (c)] Force such as differential-pressure of the order of 0.1 inch water gauge, is measured by the energizing current in an electromagnetic force-balancing device, comprising a moving- coil speaker-type unit energized by an amplified signal from a positional-displacementdetector. A manometer head unit, Fig. 1, comprises a gas-tight enclosure formed by two half-casings 4 mounted on a vertical ring 3, and a rigid diaphragm 6 sealed to the ring by an annulus of gold-beaters skin 11, and attached to a rod 7 supported on spring-pillars 13 for axial movement. One end of the rod carries a moving coil 9 co-operating with a pot magnet 10a to produce the balancing force, and the other end carries a soft iron plunger 20 forming the movable element of the detector device comprising an energizing coil 23 and two equal and oppositely connected pick-up coils 21, 22. Pneumatic damping is provided by a perforated disc 18, with adjustable blanking plates 19, mounted close to the diaphragm 6. The working parts are enclosed in silk covers 29 to protect them from dust which may enter the casing through the pressure connections 5. For certain applications where a square law is required, the permanent magnet 10a may be replaced by an energized electromagnet connected in series with the coils (Fig. 3, not shown). The output signal from the coils 21, 22 is fed to a full-wave, grid-controlled, rectifier arrangement (see Group XL (c)), comprising tubes 32, 33 which give D.C. output varying in magnitude and polarity with the detector displacement. This output is fed through an indicator meter 37 to the moving coil unit to .balance the applied force. The Provisional Specification describes a similar pressure head, having some slight differences in constructional detail, e.g. the plunger 20 comprises an ebonite rod wound with "Mumetal" (Registered Trade Mark) tape, and more current is required to operate the balancing coil which is supplied by back-to-back connected thyratrons controlled by the detector signal which is combined with a constant amplitude quadrature voltage to provide a variable phase grid control voltage for the thyratrons, whereby the output contains a controlled D.C. component, Provisional drawing (not shown).

Inventors

• 👤 Samuel Skipton Carlisle
• 👤 Bernard Owen Smith

Bibliographic Details