Patent GB-528735-A (GB)
Title: Improvements in or relating to measuring methods and apparatus
IPC: G01N9/32
Filed: 1939-03-01
Abstract: 528,735. Electric indicating systems. BAILEY METERS & CONTROLS, Ltd. March 1, 1939, No. 6685. Convention date, March 1, 1938. [Class 40 (i)] [Also in Group XXIX] A system for treating a fluid flow has means for measuring the density during or after treatment, comprising means for varying and measuring the area of an orifice in the fluid flow to maintain a predetermined pressure difference thereacross, means for measuring the weight rate of flow, and means for comparing the two measures to determine the fluid density at the orifice. In the arrangement shown in Fig. 3, a conduit 1 leads to a coil 2 heated by a burner 3 and thence through a conduit 4 to a further heating coil 5 and away through a conduit 6. Variable throttles 13, 7 and 8 inserted in the conduits 1, 4 and 6 are operated by electric motors 15 controlled by float actuated switches 14 so as to maintain a constant pressure differential across each throttle. The throttles are secured to cams 18, 24, 29, which actuate electric contacts 76, 87, 88 adapted, depending on their displacement, to make contact for a length of time, varying in accordance with the logarithm of the corresponding orifice (13, 7, 8) area, with cams 78, 85, 86, intermittently and synchronously rotated through one revolution by self-starting synchronous motors 79, 83, 84 controlled by a segment 82 on a drum 80 continuously rotated by a motor 81. Closing the contacts 76, 78, completes the circuits through the windings 90, 102 of two synchronous motors 91, 103. Contacts 85, 87 complete the circuit through an opposed winding 92 of the motor 91 and contacts 86, 88 energize a similar winding 104 on the motor 103. As long as both windings of each motor are energized for the same length of time the armatures 93, 105 do not move. If however one winding is energized longer than the other, contacts 98 or 105 are displaced according to the difference of the logarithms of the two orifice areas concerned in one direction or the other so that when the motors 96, 108 are successively energized by segments 97, 109 on the drum to rotate long arithmic cams 94, 95, 106, 107 through one revolution the contacts 98, 105 are each returned to normal by one or other of the two associated cams with which they make contact through the coil of a motor 100 for a time proportional to the antilogarithm of the logarithmic difference in question. Manually operable switches are included in the circuits to this motor so that one or other of the contacts 98 or 105 may be cut-out. Energization of the motor 100 effects a certain displacement of a contact arm 101 so that when a cam 113 is rotated through one revolution by a motor 112 controlled by a further segment on the drum, contacts 101, 114 complete a circuit through one coil 115 of a motor 116. A second opposed coil 120 of this motor is energized during the time a cam 118 rotated by a motor 117 synchronized with motor 112 is in engagement with a contact arm 119 positioned by a lever coupled to the index pointer of a combined density indicator and recorder 110, 123. If the coils are not energized for the same length of time the motor armature is rotated in one direction or the other to move the index pointer 110 to a new position.