PVC Static Mixer

Product Overview

The ywmixing PVC static mixer is the lowest-cost member of the all-polymer mixer family. The housing, flanges, and internal elements are all manufactured from rigid unplasticized PVC (PVC-U), the same material used in Schedule 80 PVC pressure piping. There are no metallic wetted parts, no lined steel shell, and no exotic polymers. The result is a mixer that handles dilute mineral acids, alkalis, and salt solutions at a price point that is typically 30-50% below the equivalent PP version.

The mixer is designed for laboratory, pilot-plant, and light-duty industrial service. It is commonly installed on chemical dosing skids, in water-treatment pilot rigs, on educational teaching loops, and in any application where the chemistry is mild and the temperature is below 60°C. The light weight (a DN50 all-PVC mixer weighs about 1.5 kg) and the simple connection (flanged, threaded, or solvent-weld socket) make the mixer easy to install and to integrate into existing PVC piping systems.

The temperature limit is 60°C continuous, 70°C short-term. Above 60°C, the PVC begins to soften and the housing will distort under any sustained pressure. The pressure limit is PN6, lower than the steel-shell lined versions. For higher temperature, higher pressure, or larger diameter, the PVC-lined mixer (steel shell with PVC liner) is the appropriate upgrade. For higher temperature with dilute chemistry, the all-PP mixer is the right selection.

Material Properties

Rigid unplasticized PVC (PVC-U) is the mixer material. Its chemical resistance is well documented: it handles all dilute mineral acids (HCl up to 20%, H₂SO₄ up to 50%, HNO₃ up to 30%, H₃PO₄ any concentration), most organic acids (acetic, citric, lactic, formic) at ambient temperature, all alkalis (NaOH, KOH, NH₄OH, Ca(OH)₂), and all salt solutions (NaCl, CaCl₂, Na₂SO₄, ferric chloride, sodium hypochlorite below 12% available Cl₂). The temperature limit is the key constraint: PVC softens at 60-65°C and the housing will distort if pressure is applied above this temperature.

The mechanical properties of rigid PVC are the strongest of the three polymer options. Tensile strength is 50-60 MPa, density 1.40-1.45 g/cm³, and elastic modulus 3.0-3.5 GPa. These properties give the PVC mixer the highest pressure rating of the all-polymer family (PN6 for the all-PVC vs PN10 for PP and PVDF). The trade-off is the temperature ceiling: PVC cannot be used above 60°C continuous, while PP and PVDF tolerate 90°C and 140°C respectively.

PVC has well-known chemical limitations. It is NOT suitable for ketones (acetone, MEK, MIBK), esters (ethyl acetate, butyl acetate), aromatic hydrocarbons (benzene, toluene, xylene), chlorinated hydrocarbons (methylene chloride, chloroform, perchloroethylene), concentrated sulfuric acid above 70%, or any service above 60°C. For any of these services, the all-PP or all-PVDF mixer is the appropriate upgrade. PVC is also unsuitable for service with strong oxidizers at elevated concentrations (concentrated HNO₃ above 50%, concentrated H₂O₂ above 30%) because these chemicals attack the polymer.

The thermal expansion coefficient of PVC is high (70 × 10⁻⁶/°C, roughly 6× that of carbon steel) but is the lowest of the three polymer options. The expansion must be accommodated in the piping system design by including expansion loops or by selecting a piping layout that does not constrain the mixer. For long straight runs, expansion compensators (bellows or expansion loops) are recommended at intervals of approximately 6-10 m to absorb thermal growth.

Construction Design

The all-PVC mixer is built almost entirely from off-the-shelf PVC pressure-piping components. The housing is a length of Schedule 80 PVC pipe (sized to the mixer DN), with two socket fusion or flanged end caps. The internal element set consists of 4-8 PVC rods, twisted 180° left and right in alternating pairs, and mechanically fastened to the housing at each end by element holders that are solvent-welded to the housing wall.

All PVC components are joined by solvent welding. The solvent cement (typically a mixture of tetrahydrofuran, cyclohexanone, and PVC resin) softens and fuses the PVC surfaces into a single homogeneous mass. Solvent-welded joints are as strong as the parent PVC and are leak-tight at the rated pressure. The cure time depends on the ambient temperature and the cement grade, but 24 hours at 20°C is typically required before the joint is put into service.

End connections are available in three styles. Flanged (ANSI B16.5 Class 150, DIN PN10, JIS 10K) is the most common — flanges are PVC ring flanges with a 316L stainless backing ring to distribute the bolt load. Threaded (NPT or BSP) is available for DN15-DN50 in PVC for instrument-air and low-pressure water service. Socket fusion (for solvent welding directly to PVC pipe) is the third option and is used where the mixer is integrated into a PVC piping system without flanged transitions.

The element set is the same helical geometry as the lined versions — left-right twisted rods at 180° (default) or 270° (option for higher viscosity). Element rod diameter is typically 0.10-0.15 × DN, and the L/D ratio of the housing is 6-10. Element count is 4-8, selected based on the target σX, with 4 elements sufficient for simple mixing duty (σX ≤ 5-7%) and 6-8 elements required for tight-coefficient applications (σX ≤ 1-3%).

The mixer is supported by standard PVC piping supports; the light weight (1.5 kg for DN50) means that simple pipe hangers or straps are usually sufficient. For horizontal installations, supports are placed at 1-2 m intervals along the piping run, with at least one support within 300 mm of each mixer flange. For vertical installations, the mixer is supported by the pipe hangers above and below, and no additional support is required.

Technical Specifications

Parameter	Value
Housing Material	Rigid unplasticized PVC (PVC-U)
Element Material	Rigid PVC (matched to housing)
Internal Structure	180° / 270° left-right helical twist elements (4-8 elements)
Mixing Precision	σX ≤ 3-7% (Re > 10,000)
Operating Temperature	-10°C to +60°C continuous / +70°C short-term
Design Pressure	PN6 at 23°C (derated at higher temperature)
Vacuum Service	Not recommended (no vacuum rating)
Connection Types	PVC flange (ANSI 150, DIN PN10, JIS 10K), NPT/BSP thread, socket fusion
Pipe Diameter Range	DN15 to DN150
Flow Rate Range	0.05 to 100 m³/h
Viscosity Range	≤ 500 cP
Gasket Material	EPDM (standard), FKM (option)
Joining Method	Solvent welding (PVC cement per ASTM D2564)
Approximate Weight (DN50)	~1.5 kg

Applications

Laboratory chemical dosing and pilot plants. The all-PVC mixer is the standard selection for chemical dosing in laboratory and pilot-plant service. The light weight, the simple connection, and the broad chemical compatibility make the mixer easy to install on a bench-top rig or a pilot skid. The 60°C temperature limit is well above the typical laboratory ambient (20-25°C) and supports the mildly warm service that is common in pilot work (e.g., 40-50°C). The 6 bar pressure rating supports most laboratory service pressures.

Water-treatment pilot and demonstration rigs. Portable water-treatment skids used for demonstration, training, and pilot evaluation use all-PVC mixers for the in-line dosing of coagulants, pH adjusters, and disinfectants. The low cost of the PVC mixer keeps the total skid cost low, and the chemical resistance handles the dilute chemistry (typically 1-10% reagent concentration) used in pilot work. The 6 bar pressure rating is well above the typical pilot-skid operating pressure of 1-3 bar.

Chemical-engineering teaching laboratories. Universities use all-PVC mixers in undergraduate unit-operations laboratories for residence-time distribution, reaction kinetics, and mass-transfer experiments. The PVC mixer is visually identifiable (typically light gray), the cost is low enough that each student group can have its own mixer, and the chemical resistance handles the typical reagent set (dilute acids, dilute bases, salt solutions) used in undergraduate lab work.

Aquarium and aquaculture water-treatment systems. The all-PVC mixer is widely used in public aquariums, aquaculture facilities, and aquatic-life support systems for the in-line dosing of water-treatment chemicals (sodium bicarbonate for alkalinity, calcium chloride for hardness, sodium thiosulfate for chlorine neutralization). The PVC material is safe for aquatic life and does not leach metallic ions that could harm sensitive species. The 60°C temperature limit is well above any aquarium operating temperature.

Swimming-pool chemical feed systems. Commercial swimming pools, water parks, and aquatic centers use all-PVC mixers for the in-line injection of sodium hypochlorite (12.5% available Cl₂) and muriatic acid (20% HCl) into the recirculation loop. The PVC mixer handles the dilute chlorine chemistry at ambient temperature, and the 6 bar pressure rating supports the typical pool-system operating pressure of 1-2 bar. The light weight simplifies mounting on the equipment pad.

Low-cost chemical process skids. OEMs of chemical process skids use the all-PVC mixer as a standard component in their water-treatment, neutralization, and precipitation skids. The low cost and the simple connection make the mixer easy to integrate into a skid design, and the broad chemical compatibility covers the typical reagent set used in skid-based water-treatment applications.

Frequently Asked Questions

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