Patent GB-484807-A (GB)
Title: An improved hydrometer and arrangements for the remote control of liquids
IPC: G01N9/26
Filed: 1936-11-10
Abstract: 484,807. Electric control and signalling systems. THIELERS, E. M., VIGREN, S. D., and KAFSTEN, S. H. Nov. 10, 1936, Nos. 30675 and 30676. Convention dates, Nov. 14, 1935 and July 21, 1936. [Class 40 (i)] [Also in Groups XX, XVIII, and XXXV] The specific gravity and /or level of a body of liquid, e.g. the electrolyte in an accumulator, is indicated or controlled by the movements of the surface of contact between the liquid and a hydrostatically balanced column of indicating liquid, which is a non-conductor of electricity and is immiscible with, and in direct contact with the liquid to be tested. Means responsive to changes of level of the liquid to be tested and means responsive to movements of the indicating liquid may be combined to indicate and/or control simultaneously both the level and the specific gravity. As shown in Fig. 9, the vessel 4 containing the indicating liquid, e.g. an oil 5, is carried by a float 1 on the surface of a body of electrolyte 3. The surface of separation 7 then moves in response to changes of specific gravity only and co-operates with spaced electrodes 34, 33, of platinum, carbon, graphite, or cadmium, to control a charging circuit for the accumulator. The vessel 4 is inclined at the bottom 32 and has an enlarged cross section at the top 32<1> in order to increase sensitivity. The float 1 may be arranged to engage a fixed bracket at a predetermined low level of the electrolyte, the movements of tlne indicating liquid then responding to changes in both level and specific gravity. In Fig. 12, the vessel 35 and float 40 are enclosed in a chamber 49 which forms part of the accumulator cell and is provided with shoulders 43 to engage the float 40. The vessel 35 carries a central electrode 38 connected to a fixed contact 54 by a cup of conducting liquid 53, as shown, or by a spiral spring. The electrode is in the circuit of an alarm or automatic charging device. Fig. 15 shows the indicating liquid 61 in a tube 81 fixed to the container 80. An alarm circuit is closed when the three solenoid windings 86, 87, 88 are de-energized. One pole of a battery 91 is connected through the winding 86 to an electrode 83 in the tube 81, through resistance 89 and the winding 8 to a lower electrode 84, and through a resistance 90 and the winding 88 to a still lower electrode 85. The other pole of the battery 91 is connected to an electrode 92 in the liquid 60 being tested. The windings 87, 88, are short circuited when the level 95 of the liquid 60 is above a pair of spaced electrodes 93. 94. In operation, when the level 95 is above the electrode 93, the alarm circuit is closed when the contact surface 62 between the indicating liquid 61 and the liquid 60 falls below the electrode 83 and cuts out the winding 86. If the level 95 is below the electrode 93 but above the electrode 94 the alarm circuit is closed only when the surface 62 falls below the electrode 84. Similarly if the level 95 is below both electrodes 93, 94, the surface 62 must fall below the electrode 85 before the alarm circuit is closed. In a further construction the tube for the indicating liquid is formed by an integral compartment of the casing for the liquid being tested and a graduated window is provided for observation of the movements of the surface of separation between the two liquids. In the form shown in Fig. 17, a depending resistance 122 at the surface 106 of the electrolyte of an accumulator is connected through a galvanometer 118 for indicating changes of level and through one coil 115 of a two coil galvanometer 113. A second depending resistance 110 at the contact surface 102 between the electrolyte and the indicating liquid is connected to the opposed coil 114 of the galvanometer 113, which therefore indicates changes of specific gravity dependently of changes of level. The measuring current is provided by the accumulator itself.