Screen Feed Controls for Melt Filtration

 

Screen Feed Controls are the instruments that regulate the movement of the filter screen. The algorithm we have developed has been refined over decades, in thousands of applications. Directed by this logic, our screen changers become a fully integrated element of the extrusion line, delivering optimum performance.

Controls fall into two main categories 'CLOSED LOOP' ("TIME CYCLE™" & "PRESSURE OVERRIDE™"), and PLC based 'FLIP/FLOP™' (On/Off):

 

'CLOSED LOOP' "TIME CYCLE™" Controls

The CLOSED LOOP algorithm uses our proprietary  Screen Guide & Resolver Assembly™ to monitor and ensure a consistent rate of screen movement.

TIME CYCLE™ based controls operate on an algorithm that generates an operating cycle by which the screen advances in time cycles at a constant rate. The rate (inches or mm per hour) of screen travel is programmable and is automatically maintained by means of a feedback loop - the Resolver Assembly™. 

The controls automatically compensate for minor variations in processing conditions such as fluctuations in head pressure or water temperature to maintain a consistent rate of screen advancement. This allows for fine tuning to the specific parameters of a given application, maintaining steady head pressure and conserving screen consumption. 

Features and benefits of Closed Loop TIME CYCLE™ based controls

closed loop time cycle overide control panel for screen changer melt filtration of polymer extrusion

'CLOSED LOOP’ “PRESSURE OVERRIDE™ Controls

The CLOSED LOOP algorithm uses our proprietary  Screen Guide & Resolver Assembly™ to monitor and ensure a consistent rate of screen movement.

‘CLOSED LOOP’ “PRESSURE OVERRIDE™" controls incorporate all the features of the TIME CYCLE™ algorithm, i.e., a constant rate of screen advancement  is maintained via a feedback loop.  The additional PRESSURE OVERRIDE™ (or Differential ΔP Pressure) feature automatically increases the rate of screen advancement by continuously monitoring the pressure before the screen (P1) - or the differential pressure across the screen (ΔP) -  to maintain uniform processing pressure (head pressure). The distance of screen advancement in both Time and Pressure Cycles is programmable to achieve a precise rate of movement, allowing for fine tuning to the specific parameters of a given application.

 

Features and benefits of Closed Loop PRESSURE OVERRIDE™ based controls

closed loop pressure override control panel screen changer for melt filtration polymer extrusion

PLC based FLIP/FLOP™ (On/Off) Controls

The operating mode of these controls is based on an  ON/OFF algorithm which produces repetitive, cyclical rates of screen travel. Parameters settings can be modified via the PLC display.

 

Features and benefits PLC based FLIP/FLOP™ (On/Off) Controls

 

HITECH™ fully automatic, continuous screen changers are used for polymer melt filtration in every segment of plastics processing: blown film, blow molding, sheet and film extrusion, filaments & fibers, pipe and profile, pelletizing, BOPP and BOPS; and our melt filters are designed to be used with all families of thermoplastics, including Polyethylene (LDPE, LLDPE and HDPE) Polystyrene (PS), Polycarbonate, ABS, Flexible PVC, PA 6, PA 66, PET, Nylon, as well as a wide range of engineering resins.

Request a quote for: Screen Changers Filters Parts
HITECH™ The Leaders in Continuous Melt Filtration since 1969