Abstract: A method for controlling reaction temperature for a reaction vessel having a flow channel for a heat transfer medium for heating or cooling or both when vinyl chloride-based monomer is polymerized in an aqueous medium, which entails employing two or more independent flow channels and feeding two or more coolants having different temperatures to the independent flow channels to thereby cool the reaction vessel.

Abstract: Method and apparatus for separating a doubled yarn into single yarns in order to piece a doubled yarn. The doubled yarn is separated by separating members such as a clamper opened and closed in a manner of scissors, push- and separate member having an extreme end sharpened, and a plurality of yarn separating rollers having tapered portions being placed in contact with each other. Feelers or sensors may be located to provide a yarn separation signal.

Abstract: A device for detecting a doubled yarn includes a detecting device having photoelectric sensors disposed in a plane perpendicular to a running path of a yarn provided in a housing such that beams of light projected from light projecting elements may reach light receiving elements in a perpendicularly intersecting relationship to each other. A calculating device totals up the sensed amounts individually detected by the light receiving elements of the photoelectric sensors and comparing the added up value with a reference value to detect a break of one or more of the single yarns of the doubled yarn.

Abstract: A spinning apparatus provided with a knotting truck moving along many spinning units. The knotting truck includes a yarn breakage detecting mechanism detecting a yarn breakage indicating plate of a unit where slub yarn breakage occures and a detecting mechanism detecting an impediment signal display plate of a unit where natural yarn breakage occurs. The knotting truck is only stopped at the position of the unit where slub yarn breakage occurs.