Patent GB-799134-A (GB)
Title: Temperature responsive control unit and steam trap employing such a unit
IPC: F16T1/08
Filed: 1956-01-06
Abstract: 799,134. Temperature-responsive actuating-elements; steam traps. VELAN ENGINEERING CO., Ltd. Jan. 6, 1956 [Feb. 16, 1955], No. 594/56. Class 64(2) [Also in Group XXIX] To prevent the outflow of steam from a steam trap, an outlet valve 32 is pulled on to its seat 24 by the bending of two bimetallic devices connected so that their movements are additive, and at least one of the devices has at least two bimetal elements which come into operation successively as the temperature rises In Figs. 3, 5, each device 42, 43 is shown as con sisting of three bimetal strips connected at their middles by spacers 44 and the inner strips of the devices are pivotally interconnected at their ends by lugs 45 so that a temperature rise causes these inner strips to bow and the middles to move apart as shown. In practice, each strip comprises a number of bimetal plates. The whole assembly is supported by the sliding fit of an attached sleeve 41 over a tubular extension 29 of the valve seat member 24. The bevelled end of the sleeve 41 enables the device to be adjusted by the raising or lowering of a bifurcated wedge 55, through a ball joint 66, by a rod 60, which extends through a plug, Fig. 2 (not shown), in the trap casing 10. A stem 30 attached to the valve 32 passes loosely through both the tube 29 and the bimetallic devices while a nut 33 at its free end bears against the outer strip of the device 43 for the transmission of the force of the bimetals to the valve 32. When condensate and air enter the trap they push open the valve and pass out through the valve seat member 24 but the entrance of steam, at first, causes the inner strips to bow and pull the valve 32 against fluid pressure. Increase of temperature and pressure of the steam causes extra bowing of the middle bimetal strip, Fig. 5. and they add their force to that of the inner strips acting to pull the valve. Further increase brings the outer strips of the devices 42, 43 into action as in Fig. 3, and the devices then exert their maximum force. The casing 10 includes a glass window, Fig. 1 (not shown), and two bimetal thermometers, Fig. 2 (not shown), one at the outlet and one at the inlet where it projects into a strainer. In another embodiment, Fig. 7, one bimetal device, having a series of strips 142a, 142b, each secured at one end, bears a yoke 150 in which is mounted a second bimetal device 145 so that the movements of the devices are additive. The valve stem 30 passes through a notch 148 in the first device and a middle hole in the second. Because the bifurcated adjusting wedge 55 in this embodiment is at the free end of the valve stem, it is mounted, as in a further embodiment, Fig. 10, on a shaft 163 to permit of movement with the bimetal deflection. In Fig. 10, the lower ends of two bimetal devices 242, 243, each comprising two elements, are secured on a shaft 260 slidably mounted at its ends in holes 262. In this embodiment the devices 242, 243, deflect away from each other and the first 242, bears a fulcrum member 270 engaging the valve seat member 24 to move the whole assembly away from the seat. The second device 243 bears on a member 280 sliding on the valve stem 30. Specification 737,936 is referred to.