Patent GB-843647-A (GB)
Title: Steam trap
IPC: F16T1/08
Filed: 1957-07-31
Abstract: 843,647. Steam traps; temperature-responsive actuating-elements. BAHR, A. July 31, 1957 [Aug. 15, 1956], No. 24215/57. Class 64(2) [Also in Group XXIX] A .bimetal assembly 72, 73, Fig. 11, clamped at one end between a bar 82 and a rocker block 83, is mounted in a chamber 16 of a steam trap between an inlet 2 and an outlet 3 and consists of at least two sets 72, 73 of bimetal strips, the sets being of different longitudinal curvature as shown so that, as steam enters the chamber 16 and heats the assembly, the free ends of the sets deflect towards the inlet 2 and, proportionately to the temperature rise, the mutual contact area between adjacent bimetal sets increases until eventually, if the temperature is high enough, the sets have no gap between them. The bimetal deflection draws a valve ball 17 on to its seat 14 in the air- and condensate-outlet 3 and the force applied to the valve is said to increase with temperature rise in a manner similar to the increase of saturated steam pressure. The operation of the trap is adjusted by means of a screw 90 in contact with the bimetal assembly 72, 73 and turning of the screw rocks the assembly about an edge 87 of the block 83 on a ledge 34 to which the block is loosely attached by pins 85 which also anchor a cranked portion of an end bimetal strip 75. The valve ball 17 is connected to the strip 75 by a stem 70 passing through notches at the lower edges of the bimetal sets 72, 73 and hooked to a pin 78 held by the strip 75. In a similar trap, Figs. 1-7 (not shown), a straight valve stem has a squaresectioned member threaded on its end, the member being located in notches at the lower edges of the bimetal sets and bearing a cross pin engaging a cranked bimetal strip at the end and in this embodiment the bimetal assembly is not adjustable since the block to which it is clamped is bolted to the ledge 34. A strainer 8 is held between a bevelled edge 7 near the inlet 2 and a similar edge in a draining plug 10. In another embodiment, Fig. 9 (not shown), the bimetal sets are clamped together at their middles and the valve stem passes through apertures at their middles. The ends of the sets co-act with a shoulder, formed in the trap housing, as the sets bow with temperature rise. In a similar embodiment, Fig. 10, in which there are two pairs, 60, 61 and 62, 63, of bimetal sets, the stem again passes through apertures at the middles. and through a hole in a fixed transverse bar 59 to which the first pair of sets 60, 61 is screwed and which acts as an abutment so that bowing of the inner sets 61, 62 draws the valve 17 on to its seat. The second pair of sets 62, 63 are bolted together. The end of the stem bears nuts 64. Rotation of the bimetal strips is prevented by rods 65 passing through holes in the ends of the strips while a pin 66 on each rod acts as a spacer between the pairs of sets. In both these latter embodiments, as before, the gap between the adjacent sets gradually lessens as the temperature rises and so the force applied is increased. The bowing of the bowed sets, e.g. 61 and 62, increases and the straight sets, e.g. 60 and 63, bow to the same shape eventually.