THE TEST EQUIPMENT OF FRICTION COEFFICIENT OF VALVE PACKING AND METHOD THEREOF

摘要

PURPOSE: A device and a method for testing a frictional coefficient of a valve packing are provided to accurately measure gland stress by directly measuring stress added on a gland stud. CONSTITUTION: A method for testing a frictional coefficient of a valve packing is as follows. A packing gland is fixed to the upper part of a packing unit mounted inside a valve by a medium of a gland stud and a gland nut, and the initial height of the packing gland(S1). The gland nut fixed to the upper part of the packing unit is fastened so that gland stress corresponding to a preset stress value is generated(S2). The gland stress and a packing frictional force are measured by using a strain gauge after driving unit make a valve stem vertically reciprocate once with an applied driving force(S3). Previous steps are repeated until a difference between stress values before and after a reciprocating motion of the valve stem reach a preset range, so that the packing units are compressed(S4). The gland stress and the packing frictional force are successively measured by performing the vertically reciprocating motion of the valve stem several times after measuring the final height of the packing gland and the frictional coefficient of the valve packing is calculated by using the measured gland stress and the packing frictional force(S5). [Reference numerals] (AA) Start; (BB) End; (S1) Fixing a packing gland to the upper part of a packing unit mounted inside a valve by the medium of a gland stud and a gland nut and the initial height of the packing gland; (S2) Tightening the gland nut fixed to the upper part of the packing unit to generate gland stress corresponding to a preset stress value; (S3) Vertically reciprocating a valve stem once with an applied driving force and measuring the gland stress and a packing frictional force by using a strain gauge; (S4) Compressing packings by repeating the step S3 until the difference between gland stress values before and after the reciprocating motion of the valve stem reach a preset range; (S5) Measuring the final height of the packing gland, successively measuring the gland stress and the packing frictional force by vertically reciprocating the valve stem several times, and calculating a packing frictional coefficient by using the measured gland stress and packing frictional force