Durastream CPVC vs. PVC Processing
Can We Use a PVC Machine for CPVC Production?
The CPVC process using extrusion and injection is very similar to the PVC process.
PVC equipment and tools can typically be used in the CPVC manufacturing process. However, proper temperature settings, screws, and molding tools will be necessary.
What Is the Main Difference Between CPVC and PVC Processing?
The main difference between PVC and CPVC processing is in thermal stability and viscosity.
If moderate temperatures and heat are not applied to CPVC, CPVC will not melt and physical properties will not be performed well. Hydrochloric acid decomposes when exposed to high temperatures. The crystalline melting points for PVC and CPVC are pictured below.

Can We Use a PVC Machine for CPVC Production?
Key Points
PVC and CPVC materials have different thermal stabilities.
- CPVC materials need to reduce the residence time of the molding tools as much as possible.
- Resin temperature settings are important to ensure the melting and gelation of the material.
Viscosity (Fluidity)
CPVC viscosity is generally higher than that of PVC. PVC viscosity can simply be read as K-Value=Polymerization. In the case of CPVC, viscosity (K-Value) is calculated by PVC polymerization degrees and chlorination degrees.
Key Points
- Motor Load, Back Pressure
If back pressure is high and it’s hard to increase production speed, the material will remain inside the die for longer and burn. - Screw/Mold Shape
The structure of the screw and die tools is an important factor. The tools need to be matched with CPVC production. - Attention to Shear Heating
The screw undergoes shear heating. Moderate heat is required to keep the plastic at the correct temperature.
Processing Differences: PVC vs CPVC
Extruder
PVC | CPVC | ||
Machine | Screw Mortar:High Torque Screw:Parallel φ60-170 Conical φ50-85 |
Screw Mortar:High Torque Screw:Parallel φ60-135 Conical φ50-70 |
|
Condition | Screw Rotation | ー | Lower than PVC |
Barrel Temp. | 300 – 340 ℉ | 340 – 410 ℉/span> | |
Mold Type | Stainless Steel Chrome Plate | Stainless Steel Chrome Plate Less volume (residence part) Mold angle |
*These reference values are not guaranteed.
Injection
PVC | CPVC | ||
Machine | Screw Mortar: High Torque Barrel Cooling: Blower |
Screw Mortar: High Torque Barrel Cooling: Blower Barrel Zone: 4-5 Zone Nozzle: Short Nozzle、φ:Larger than PVC |
|
Condition | Screw Rotation | 9-14 m/sec | 8-13 m/sec (lower than PVC) |
Barrel Temp. | 320 – 365 ℉ | 320 – 392 ℉ | |
Holding Pressure | 100 – 170 MPa | 100 – 170 MPa | |
Mold Type | Stainless Steel Chrome Plate Runner: Thick Hot Runner: No Need Gate: Direct Gate Wall Thickness > Gate Diameter |
Stainless Steel Chrome Plate Runner: Thick Hot Runner: No Need Gate: Direct Gate Larger than PVC |
*These reference values are not guaranteed.
Single Extrude (Profile)
PVC | CPVC | ||
Machine | Single Screw Machine Screw: Dulmate, Fullfight |
Single Screw Machine Screw: Recommend Fullfight (Dulmate) L/D = 22 – 25 Compression Ratio: 2.5 – 3.2 |
|
Condition | Screw Rotation | 15~ rpm (65mm single) | 15–25 rpm (65mm single) |
Barrel Temp. | 284 – 338 ℉ | 300 – 370 ℉ | |
Mold Type | Stainless Steel Chrome Plate | Stainless Steel Chrome Plate |
*These reference values are not guaranteed.