A new recirculating oil sealed vacuum pump package has been introduced by Leistritz for use with its range of twin screw extruders and other type/model extruders. The recirculating oil ring pump is replacing once-through water sealed vacuum pumps to pull vacuum from extruder vents to enhance devolatilization efficiencies. The vacuum pump typically can be operated 2 to 6 months before the oil needs to be replaced. The main advantage of the oil sealed design is that it eliminates the environmental concerns associated with water disposal from the water sealed pump.
The system includes a TEFC motor and an oil reservoir with built-in baffles equipped with filter, sight glass and drain valve. The oil is cooled using a rear-mounted heat exchanger with the fan driven by the pump motor. The oil return line includes a temperature gauge and fixed orifice flow control valve. The vacuum line has a shut-off valve, check valve and gauge. A knockout pot with filter is situated between the extruder and pump. All components are mounted on a steel base plate.
Plumbing connections can mate to multiple vents from the same pump. Two traps/filter with quick disconnects and a 3-way valve can be used with the same pump for changeover while processing. Custom systems may also be specified with dry filters, liquid separators, chilled liquid condensers, and closed loop vacuum level adjustment.