GB253984A - Improvements in and relating to means for controlling chemical reactions - Google Patents

Abstract

253,984. British Thomson-Houston Co., Ltd., Warren, H. W. H., Newbound, R., and Bell, L. M. T. March 20, 1925. Thermostats.-A device for controlling chemical reactions accompanied by a rise in temperature, and especially for ensuring that a particular rise in temperature shall not be exceeded within a predetermined period of time, comprises a contact-member driven at a constant speed, and a second contact-member moved by temperature sensitive mechanism behind and along the same path as the first contact-member, the arrangement being such that should the second member overtake the first an electric circuit is completed whereby corrective, devices are brought into play. A spindle 2, Fig. 1, the movements of which are transmitted by gearing 5, 6, to a sleeve 7, is adapted to be turned by temperaturesensitive mechanism 1 located in the medium to be controlled. The sleeve 7 carries an arm 8 and is traversed by a spindle 10 driven at constant speed and carrying an arm 11. The arm 8, Fig. 3, normally moves over a dial 9 along the same path as and behind the arm 11, and if, on account of a too rapid rise in temperature, the arm 8 overtakes the arm 11 an electric circuit is completed and a corrective operation, such as cessation of heating, is automatically performed. The dial 9 may carry a contact 16 arranged to be cleared by the arm 11 but to be engaged by the arm 8 should the temperature continue to rise, the engagement of the arm 8 and contact 16 completing a circuit whereby cooling fluid is caused to be supplied to or around the reaction vessel. Also, a second contact-carrying arm 18 may be mounted on the spindle 10 so as normally to move behind the arm 8, the arrangement being such that, should the temperature rise too slowly so that the arm overtakes the arm 8, a circuit is completed whereby other corrective means are operated. The temperature-sensitive mechanism 1 may comprise, as shown in Fig. 2, a bimetallic strip 23 fixed at one end 24 to a casing 25 and free to bend with variations in temperature so as to operate a quadrant-shaped rack 26 pivoted to the casing at 27 and engaging a pinion 28 on the spindle 2. Specification 225,011 is referred to.