Application

Vacuum pumps for extruder degassing and extrusion

In the degassing zone of the extruder, vacuum draws water vapour, air and volatile substances out of the plastic melt before it passes through the die; after the extruder, vacuum holds the profile or pipe in shape and to size in the calibration tank. Edwards describes the removal of water vapour and gases from the melt, Atlas Copco the constant vacuum for dimensional accuracy in calibration. Below you can see how the application works, what vacuum the manufacturers name and which of their series are intended for it – 377 models from 5 manufacturers.

Compare 377 modelsHow it works

  • 377Models
  • 22Series
  • 5Manufacturers
  • 3–3,500 m³/hPumping speed for extruder degassing (Edwards)
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Touch the points: each part of the system explains itself.

In short

Extruder degassing and extrusion: the key facts

  • DegassingEdwards describes extruder degassing as the removal of water vapour and gases from the melt and names GXS, EDS and the liquid ring series LR1A, LR1C and LR1D; for dry-running pumps in extruder degassing, Edwards names 3–3,500 m³/h and ultimate pressures down to 4×10⁻⁴ mbar.
  • Process pressureFor masterbatch production and compounding, Leybold names a process pressure below 50 mbar (EXTRUVAC VD) and, for small and medium-sized extruders, the CLAWVAC (EXTRUVAC CP) as an alternative to liquid ring pumps.
  • CalibrationAtlas Copco describes the constant vacuum in the vacuum calibration tank for dimensional accuracy and names 100–200 mbar(a) with GHS VSD+ for corrugated pipe production; according to Elmo Rietschle, vacuum calibrators ensure shape and dimensions.
  • SeriesFor profile, film and sheet extrusion and compounding, Busch names MINK, DOLPHIN, COBRA and HUCKEPACK, and for calibration also SAMOS; Pfeiffer Vacuum names HiLobe; Atlas Copco DZS, DWS, AWC, LRP VSD+ and GLS.
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  • Air and gas (vacuum)
  • Exhaust

Operating principle

How it works: Extruder degassing and extrusion

The drawing shows the basic principle in section. The systems and pumps of the individual manufacturers differ in detail.

  1. MeltingThe screw plasticises the granulate; moisture and volatile substances are released in the melt.
  2. DegassingIn the degassing zone, according to Edwards, the vacuum draws water vapour and gases out of the melt; for compounding, Leybold names process pressures below 50 mbar.
  3. CalibratingAfter the die, the vacuum calibration tank keeps the profile dimensionally stable and true to size (Atlas Copco); for corrugated pipes, Atlas Copco names 100–200 mbar(a) in a moving vacuum mould.

Vacuum and sizing

Extruder degassing and extrusion: how much vacuum is needed

What the manufacturers say about pressure, pumping speed and sizing.

Which vacuum

For masterbatch and compounding, Leybold names process pressures below 50 mbar; for dry-running pumps in extruder degassing, Edwards names ultimate pressures down to 4×10⁻⁴ mbar; Atlas Copco 100–200 mbar(a) for corrugated pipe production.

Which suction capacity

For dry-running pumps in extruder degassing, Edwards names 3–3,500 m³/h.

What determines the sizing

The size of the extruder and the process: Leybold names CLAWVAC for small and medium-sized extruders and VARODRY (EXTRUVAC VD) for small extruders with less demanding processes. Busch distinguishes profile, film/sheet extrusion and compounding (MINK, DOLPHIN, COBRA, HUCKEPACK) from profile calibration (DOLPHIN, MINK, SAMOS).

What the manufacturers point out

They point to water vapour and gases in the melt (Edwards), to a stable vacuum in the degassing zones for compounding and masterbatch (Edwards) and to the alternative to liquid ring pumps (Leybold). For confectionery, Busch describes vacuum extrusion, which draws air bubbles out of the mass (MINK, DOLPHIN, and in the product finder also R5).

Technology

Extruder degassing and extrusion: the vacuum pumps the manufacturers name

Listed are the series the manufacturer itself names for this application. “Show only …” sets the filter of the product overview.

Becker names the application without naming a series for it. Elmo Rietschle names the application without naming a series for it.

Product overview

Extruder degassing and extrusion: all 377 models compared

Use the filters on the left to narrow the selection – by manufacturer, technology and the models’ key figures, for 50 or 60 Hz.

Atlas Copco AWC series 9 models

AWC 30Pumping speed 27 m³/h 50 Hz32 m³/h 60 HzUltimate pressure 33 mbarRated motor power 1.1 kW 50 Hz1.5 kW 60 HzVariants 6
AWC 50Pumping speed 52 m³/h 50 Hz62 m³/h 60 HzUltimate pressure 33 mbarRated motor power 1.5 kW 50 Hz2.4 kW 60 HzVariants 6
AWC 80Pumping speed 80 m³/h 50 Hz96 m³/h 60 HzUltimate pressure 33 mbarRated motor power 3 kW 50 Hz4 kW 60 HzVariants 6
AWC 110Pumping speed 110 m³/h 50 Hz130 m³/h 60 HzUltimate pressure 33 mbarRated motor power 3.85 – 4 kW 50 Hz6.3 kW 60 HzVariants 9
AWC 160Pumping speed 165 m³/h 50 Hz185 m³/h 60 HzUltimate pressure 33 mbarRated motor power 4 kW 50 Hz5.5 – 6.3 kW 60 HzVariants 15
AWC 220Pumping speed 230 m³/h 50 Hz265 m³/h 60 HzUltimate pressure 33 mbarRated motor power 5.5 kW 50 Hz7.5 – 8.2 kW 60 HzVariants 15
AWC 290Pumping speed 280 m³/h 50 Hz310 m³/h 60 HzUltimate pressure 33 mbarRated motor power 7.5 kW 50 Hz11 – 12.6 kW 60 HzVariants 15
AWC 390Pumping speed 400 m³/h 50 Hz420 m³/h 60 HzUltimate pressure 33 mbarRated motor power 11 kW 50 Hz15 – 16.5 kW 60 HzVariants 15
AWC 500Pumping speed 500 m³/h 50 Hz535 m³/h 60 HzUltimate pressure 33 mbarRated motor power 15 kW 50 Hz18.5 kW 60 HzVariants 15

Atlas Copco DWS series 3 models

DWS 200Pumping speed 210 m³/h 50 Hz210 m³/h 60 HzUltimate pressure 0.05 mbarRated motor power 5.5 kW 50 Hz5.5 kW 60 HzVariants 14
DWS 300Pumping speed 280 m³/h 50 Hz280 m³/h 60 HzUltimate pressure 0.01 mbarRated motor power Variants 14
DWS 500Pumping speed 460 m³/h 50 Hz460 m³/h 60 HzUltimate pressure 0.01 mbarRated motor power Variants 7

Atlas Copco DZS series 8 models

DZS 065APumping speed 65 m³/h 50 Hz78 m³/h 60 HzUltimate pressure 50 mbarRated motor power 1.8 kW 50 Hz2.2 kW 60 HzVariants 12
DZS 065APPumping speed 65 m³/h 50 Hz78 m³/h 60 HzUltimate pressure Rated motor power 3.7 kW 50 Hz3.7 kW 60 HzVariants 5
DZS 150APumping speed 150 m³/h 50 Hz180 m³/h 60 HzUltimate pressure 50 mbarRated motor power 3.7 kW 50 Hz3.7 kW 60 HzVariants 12
DZS 150APPumping speed 150 m³/h 50 Hz180 m³/h 60 HzUltimate pressure Rated motor power 11 kW 50 Hz15 kW 60 HzVariants 6
DZS 300APPumping speed 238 m³/h 50 Hz280 m³/h 60 HzUltimate pressure Rated motor power 19 kW 50 Hz22 kW 60 HzVariants 6
DZS 300APumping speed 300 m³/h 50 Hz360 m³/h 60 HzUltimate pressure 140 – 200 mbarRated motor power 6.2 kW 50 Hz7.5 kW 60 HzVariants 12
DZS 500 VPumping speed 500 m³/h 50 Hz600 m³/h 60 HzUltimate pressure 200 mbarRated motor power 9.2 kW 50 Hz11 kW 60 HzVariants 8
DZS 1000 VPumping speed 950 m³/h 50 Hz1,140 m³/h 60 HzUltimate pressure 200 mbarRated motor power 18.5 kW 50 Hz22 kW 60 HzVariants 8

Atlas Copco GHS VSD+ series 21 models

GHS 350 VSD+Pumping speed 400 m³/h 50 Hz400 m³/h 60 HzUltimate pressure 0.35 mbarRated motor power 5.5 kW 50 Hz5.5 kW 60 HzVariants 29
GHS 402 VSD+Pumping speed 467 m³/h 50 Hz467 m³/h 60 HzUltimate pressure 0.35 mbarRated motor power 5.5 – 7.5 kW 50 Hz5.5 – 7.5 kW 60 HzVariants 4
GHS 585 VSD+Pumping speed 560 m³/h 50 Hz560 m³/h 60 HzUltimate pressure 0.35 mbarRated motor power 7.5 kW 50 Hz7.5 kW 60 HzVariants 30
GHS 602 VSD+Pumping speed 640 m³/h 50 Hz640 m³/h 60 HzUltimate pressure 0.35 mbarRated motor power 7.5 – 11 kW 50 Hz7.5 – 11 kW 60 HzVariants 4

Atlas Copco GLS series 2 models

Atlas Copco LRP VSD+ series 3 models

Busch COBRA Industry series 36 models

Busch DOLPHIN series 70 models

Busch HUCKEPACK series 4 models

Busch MINK series 32 models

Busch PANDA/PUMA series 26 models

Busch R5 series 58 models

Busch SAMOS series 31 models

Edwards EDS series 3 models

Edwards GXS series 10 models

Edwards LR1A series 12 models

Edwards LR1C series 9 models

Edwards LR1D series 12 models

Edwards Stokes Microvac series 2 models

Edwards Stokes series 4 models

Leybold CLAWVAC series 5 models

Pfeiffer Vacuum HiLobe series 17 models

Model comparison

Models a manufacturer no longer carries in its current range are listed in its “Outdated models” section.

Industries

Extruder degassing and extrusion: where the manufacturers name it

The manufacturers list these uses on their own pages.

Plastics and recycling

The manufacturers name plastics extrusion: Edwards and Leybold describe the degassing of the melt, Atlas Copco, Elmo Rietschle and Busch vacuum calibration, while Becker and Pfeiffer Vacuum list extruder degassing without describing it.

Industry page: Plastics and recycling →

Confectionery and bakery

Busch describes the vacuum extrusion of confectionery masses, in which air bubbles are drawn out of the mass, with MINK and DOLPHIN.

Industry page: Confectionery and bakery →

Frequently asked questions

Extruder degassing and extrusion: frequently asked questions

How does extruder degassing work?

In the degassing zone of the extruder, the melt is under vacuum. According to Edwards, water vapour and gases are removed from the melt in the process; Busch describes that the vacuum removes gases and ensures quality. A separator keeps condensate and entrained melt away from the pump.

Which vacuum pump for extruder degassing?

Leybold names CLAWVAC (EXTRUVAC CP) for small and medium-sized extruders as an alternative to liquid ring pumps. Edwards names GXS, EDS and the liquid ring series LR1A, LR1C and LR1D, Busch MINK, DOLPHIN, COBRA and HUCKEPACK, and in the product finder also R5 and PANDA/PUMA. Atlas Copco lists DZS, DWS, AWC and LRP VSD+, Pfeiffer Vacuum HiLobe.

How much vacuum does extruder degassing need?

For masterbatch production and compounding, Leybold names process pressures below 50 mbar. For dry-running pumps in extruder degassing, Edwards names ultimate pressures down to 4×10⁻⁴ mbar and pumping speeds of 3–3,500 m³/h. For calibration, Atlas Copco names 100–200 mbar(a) for corrugated pipes.

Which vacuum pump for the vacuum calibration of profiles and pipes?

For profile calibration and vacuum calibration, Busch names DOLPHIN, MINK and SAMOS. Edwards lists the liquid ring series LR1A, LR1C and LR1D, Atlas Copco GHS VSD+ for corrugated pipe production. Elmo Rietschle describes that vacuum calibrators ensure shape and dimensions, without naming a series.

Liquid ring or dry vacuum pump for extruder degassing?

Both are named. Leybold presents the CLAWVAC as an alternative to liquid ring pumps for small and medium-sized extruders; alongside the dry-running screw vacuum pumps GXS and EDS, Edwards also names the liquid ring series LR1A, LR1C and LR1D; Atlas Copco lists the DZS claw vacuum pumps, the DWS screw vacuum pumps and the AWC and LRP VSD+ liquid ring vacuum pumps.

Why must gases and water vapour be removed from the melt?

Gas that remains in the melt forms bubbles and defects in the profile, the film or the sheet. Busch describes that the vacuum removes gases and thus ensures quality; Edwards names degassing in film and sheet production from PE, PP, PA and EVOH.

Which vacuum pump for compounding and masterbatch?

For this, Leybold names VARODRY (EXTRUVAC VD) at process pressures below 50 mbar, for small extruders with less demanding processes. Edwards describes a stable vacuum in the degassing zones as a requirement. For extruder compounding, Busch names MINK, DOLPHIN, COBRA and HUCKEPACK.

What vacuum does corrugated pipe production need?

Atlas Copco names 100–200 mbar(a): a moving vacuum mould shapes and cools the pipe; the GHS VSD+ is named.

What is vacuum extrusion in confectionery?

Busch describes vacuum extrusion in confectionery production: air bubbles are drawn out of the mass. MINK and DOLPHIN are named, and in the product finder also R5.

What to do when the vacuum in the degassing zone fluctuates?

For compounding and masterbatch, Edwards names a stable vacuum in the degassing zones as a requirement, Atlas Copco a constant vacuum for calibration. A control valve upstream of the pump or a frequency-controlled pump – Atlas Copco names GHS VSD+ and LRP VSD+ – holds the pressure; separators and filters must be clear so that the pump retains its pumping speed.

A single pump or a central vacuum system?

A central system in a room of its own keeps noise and heat away from production and matches its output to the demand. Central vacuum systems are planned and built by Eugen Theis Vakuum, a company of the Ehrler & Beck group – more under Central Vacuum.

Does Ehrler & Beck also supply spare parts and service?

Yes. Ehrler & Beck offers original spare parts and accessories as well as maintenance and repair.

Which pump suits your process?

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