Shut=off system for valve for thermoplastic melts - prevents mechanical locking of tapered plug and gives better sealing against polymer leakage under plug sealing faces is achieved

摘要

A shut off device for a valve with a conical bore and used for plastics melts is described in which locking of the tapered valve plug in a matching tapered bore during heating is avoided. The valve has a housing with a conical bore in which a rotatable conical plug is located. To prevent locking of the plug during heating of the valve body the plug is gently raised and lowered by a thermally expanding bolt which can be heated or cooled. The rod is fixed in the housing and lifts the plug along the long axis against the force of a spring. The arrangement prevents fluid or polymemelt penetrating under the sealing surfaces on the valve plug circumference which renders the valve ineffective. USE/ADVANTAGE - For sealing off polymer flow in a polymer filtering device. Prevents mechanical locking of the tapered plug and also stops polymer leakage under the plug edges. Expensive valve cleaning is avoided.