| 摘要 |
<p>Electric-thermostatic servo-control (4) for cutoff and adjustment valves for fluid in heating systems in general, using a motor system (6) with a thermostatic element which is electrically heated and biased by return springs for closing the cutoff valve (14) in the absence of electric power. The servo-control (4) comprises an auxiliary thermostatic element (10) having a control piston (11) interposed between the movable part of the thermostatic element which actuates the closure valve (14) and the stem (13) thereof, and at least one spring (17) coaxial to the stem (13), interposed between a flange (15) rigidly associated with the stem (13) and a fixed flange (16) arranged opposite inside the valve body. The spring (17) is coaxial to the valve-holder (1a) and has such dimensions as to be compressed when the valve (14) is in a stable closure position and deactivated, so as to react for automatically opening the valve (14) when the piston (11) of the auxiliary thermostatic element moves backwards under the effect of an environmental temperature below a certain preset value, whereby an environment can be heated to a minimum temperature to prevent freezing of the system.</p> |
