方案六

　　What

　　Seal flush from pump discharge and recirculation to pump

　　suction with orifices

　　Combination of Plan 11 and Plan 13

　　Why

　　Continuous seal chamber venting on vertical pumps .

　　Seal chamber heat removal

　　Increase seal chamber pressure and fluid vapor margin .

　　Where

　　Vertical pumps .

　　Clean ,non-polymerizing fluids at moderate temperatures

　　Preventative Maintenance

　　Use an orifice with a minimum 3 mm ( 1/8inch )diameter .

　　Calculate flow rates to size orifice for adequate seal chamber

　　flow .

　　Increase boiling point margin with proper orifice and throat

　　bushing sizing

　　Flush should be directed over seal faces .

　　Vent piping loop prior to starting vertical pumps .

　　Typical failure mode is a clogged orifice check temperatures

　　at pipe ends