A filtering device for removing dirt particles and contaminants from a plastic melt is disclosed. The filtering device includes a housing having a filter chamber, an inlet for feeding plastic melt, an outlet for channeling plastic melt out, and a dirt outlet for discharging dirt particles from the housing. The filtering device also includes a filter element arranged in the filter chamber to retain any dirt particles contained in the stream of melt, and a cleaning unit for cleaning the filter element of dirt particles retained by means of the filter element. The cleaning unit having a cleaning head with a scraper member for detaching dirt particles from the filter element. The scraper member is coupled to a servomechanism to press the scraper member onto the surface of the filter element. The servomechanism has at least one bellows cylinder including a foot section, a head section, a deformable bellows element, and a pressure chamber of variable volume.

A filtering apparatus is configured to receive pressurized fluid from a pump. The filtering apparatus has a main inlet, a main outlet, and a filtering branch comprising a first filter. An agitator of a tank from which the pump draws is configured to receive fluid flow from the filtering branch via a proportional valve and an inlet connection. A method of operating a filtering system includes influencing fluid flow from a tank to one or more nozzles via a filtering apparatus; and diverting a portion of the fluid flow through plural filters of a different mesh size back to an agitating mechanism through a lower portion of the tank.

A filtering apparatus is configured to receive pressurized fluid from a pump. The filtering apparatus has a main inlet, a main outlet, and a filtering branch comprising a first filter. An agitator of a tank from which the pump draws is configured to receive fluid flow from the filtering branch via a proportional valve and an inlet connection. A method of operating a filtering system includes influencing fluid flow from a tank to one or more nozzles via a filtering apparatus; and diverting a portion of the fluid flow through plural filters of a different mesh size back to an agitating mechanism through a lower portion of the tank.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55, 57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasably engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55,57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasably engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55,57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasably engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55, 57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasibly engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55,57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes an installable and removable valve controller housing (74) which is releasibly engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55, 57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes a installable and removable valve controller housing (74) which is releasibly engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.

A control valve (10) includes a valve body with a plurality of ports (A, B, C, D, E, F) and a plurality of annular flow passages (53, 55,57). A piston (34) which includes a plurality of annular flow passages and a longitudinal flow passage is selectively movable within a bore (32) within the valve body through operation of a valve controller (70). The valve controller is selectively operative to control the position of the piston so as to enable liquid flow through a plurality of flow paths. The valve controller further includes an installable and removable valve controller housing (74) which is releasably engageable with a valve base (72). The valve may include a changeable piston and changeable injector and plug components to adapt the valve to different flow and fluid mixing requirements.