Discussion with a Customer of the Extruder Screen Changer

One of our overseas customer ask us a question about the extruder screen changer as below: 

Customer´s Question: 

We have one 60 extruder, it is used for the extrusion of PP-R composite pipe, the maximum output is 90kg/hr, and with 20% recycled material. The extrusion working pressure is varies from 170 to 200Bar and critical pressure (when automatic stop of extruder work occurs) amounts to 230 Bar. Now we want to build in a screen changer in the line, which model for us to choose is more suitable? We want to buy a manual screen changer, because this is cheep, can we use such one? 

Reply from Shanghai Omega: 

According to the more comprehensive information we are learn now, we are afraid this Bar is too large, larger than normal, but you see, after installation of a screen changer, this pressure will be greater then before. Under such a large pressure, the manual screen changer might be able to operated in the extruder stopped state, which makes the replacement frequency of the filter net higher, and it is bound to affect the working efficiency of the extruder. Another problem is the extruder is in high back pressure for a long time, the main motor is under full load for a long time, which is unfavorable to the safe operation of the motor. 

There are two models of manual screen changer can be chosen made by our company for your 60 extuder, one is OMEGA-MS-70, and another is OMEGA-MS-100. The former is used for normal, that is there is no recycle material inside, and the extruding back pressure is less than 120bar normally. Now to review your extruder working condition, 20% recycle material and greater pressure, we propose you to choose our screen changer of OMEGA-MS-100, a larger model, due to the filter net cross-sectional area of OMEGA-MS-100 is bigger than OMEGA-MS-70, so that the increased back pressure when OMEGA-MS-100 set up in the line, will be less than OMEGA-MS-70, this can reduce the frequency of the filter screen replacement. 

Normally there are more kinds of screen changer could be chosen for an extrusion line, Manual Screen Changer you mentioned, Single-plate Hydraulic Screen Changer with Single Working Position, Double-piston Hydraulic Screen Changer with Double Working Position..., and so on. For working in with higher capacity, with recycle material, with greater extruding pressure..., we usually advice customers to use a screen changer with automatic function, In order to reduce the frequency of changing the filter, improve the working efficiency of the extruder.

In review of your 60 extruder with so larger extrusion pressure and 20% recycled material, does not affect the extruder working efficiency of the best fit, the best way is a hydraulic screen changer with automatic operation ability could be used.

Please think carefully about our advice above, thank you.

Chief Engineer Office / Shanghai Omega Machinery., Ltd