Polymer Dosing Pumps: Iwaki Series for Viscous Fluids and Flocculant Dosing
Pumps listed in Iwaki documentation for metered dosing of viscous fluids such as polymer flocculants in wastewater treatment, along with viscosity ratings and selection rules.
Three Decisions in Polymer Dosing
- What viscosity? IX-C up to 1,000, IX-D up to 300 mPa·s; G series 0.5–10,000 mPa·s; Hicera V up to 20,000 mPa·s. For the EWN-R V type, the manufacturer does not state a numerical limit.
- What flow rate? Hicera V covers mL/min, EWN-R V type 9 L/h, IX-C and IX-D 0.08–300 L/h, and G up to 35.2 L/min.
- Flow margin: Flow rate drops in viscous fluids; allow a margin during selection and verify the flow rate by calibration in the field.
Why Does a Pump Behave Differently in Viscous Fluids?
Viscous liquid passes more slowly through suction and discharge valves; in a diaphragm pump, a portion of flow is lost on every stroke. The Iwaki IX-B catalog notes that in viscous fluids, discharge capacity can drop to approximately 20 percent below the nominal rating and requires reducing the suction speed in viscous or gas-containing liquids to prevent cavitation. The IX calibration procedure emphasizes the same point: calibration performed at full suction speed with a viscous liquid frequently produces errors, so suction speed is reduced according to viscosity.
For this reason, three distinct approaches are used in polymer dosing: a diaphragm pump configured specifically for viscous liquids (EWN-R V type, IX-B viscous valve), a gear pump with a wide viscosity range (G), and a valveless plunger pump (Hicera V). Which one is selected depends on the viscosity of the polymer, the required flow rate, and backpressure. See our pumps and Iwaki pages for all dosing and process series.
Iwaki Series for Viscous Fluids
| Series | Type | Viscosity (manufacturer) | Flow rate | Pressure | Note in source |
|---|---|---|---|---|---|
| EWN-R V type (PC/P6) | Electromagnetic diaphragm | No numerical limit given; consult manufacturer | EWN-C31: 9.0 L/h (150 mL/min) | 0.5 MPa | For polymer flocculant injection in wastewater treatment; GFRPP head, Hastelloy C276 spring |
| IX-B015 / IX-B030 | Digital direct-drive diaphragm | Standard valve 100; viscous valve (special order) 1,000 mPa·s | IX-B: 0.0075–45 L/h | 0.4–1.7 MPa | Spring-loaded stainless steel viscous valve |
| IX-C060 / IX-C150 | Digital direct-drive diaphragm | Up to 1,000 mPa·s | 0.08–60 / 0.2–150 L/h | 1.0 / 0.4 MPa | Flow rate may drop in viscous fluid; allow margin |
| IX-D150 / IX-D300 | Digital direct-drive diaphragm | Up to 300 mPa·s | 0.2–150 / 0.4–300 L/h | 1.0 / 0.5 MPa | Consult manufacturer for higher viscosity |
| G (GX) | Ceramic gear pump | 0.5–10,000 mPa·s | 1.0–25.0 mL/rev; up to 35.2 L/min (50 Hz) | 1.0 MPa | SiC/SiC gears below 200 mPa·s, Si3N4/SiC above; flow proportional to speed |
| G (GM, magnetic) | Magnetic drive gear | 0.5–1,000 (GM-12/15/25); 0.5–100 mPa·s (GM-32) | 1.0–25.0 mL/rev | 0.5–0.7 MPa | Sealless; not recommended for slurry applications |
| Hicera V | Valveless ceramic plunger | Up to 20,000 mPa·s; accuracy may decline at 500 mPa·s and above | V-05: 1.6–1.9; V-10: 6.0–409; V-15: 559–1,682 mL/min | 0.2–0.7 MPa | Listed for polymer flocculant and slaked lime injection applications |
| LK (VS type) | Motor-driven mechanical diaphragm | VS type on special request for viscosity and slurry | 0.02–45 L/min (50 Hz) | 0.2–1.5 MPa | Consult manufacturer for details |
The V-05, V-10, and V-15 AC-motor models in the Hicera V row are catalog values; the V series also includes 24 VDC V-07 micro-dosing models with the same 20,000 mPa·s upper viscosity limit.
Four Approaches, Four Operating Principles
EWN-R V type
The viscous-liquid variant of the standard EWN-R platform. The brochure indicates this type for polymer flocculant injection in wastewater treatment and advises consulting the manufacturer for details. In the manual table, the EWN-C31 model delivers 9.0 L/h at 0.5 MPa; flow rate is measured with clean water. Stroke rate is 1–240 strokes/min, and stroke length is 40–100 percent.
IX-B, IX-C, IX-D
Digital direct-drive diaphragm pump with a brushless DC motor. Suction and discharge speeds are adjusted independently; suction speed is reduced in viscous fluids. Control modes are manual, 4-20 mA, pulse, batch, and interval batch. Viscosity ratings are listed in the table.
G gear pump
Ceramic-geared, pulseless, and self-priming. It can pump both low- and high-viscosity liquids; the manufacturer requires selecting motor speed and power appropriate to the viscosity. A strainer and relief valve are installed to protect the line; for adhesive or easily solidifying liquids, inquire about a model with a torque limiter.
Hicera V
Its valveless ceramic piston and cylinder structure eliminates valve clogging and sticking problems. Airlock-free operation and a suction lift capability of more than 4 m are specified. For crystallizing or adhesive liquids, the interior of the pump is flushed clean.
LK VS type
For the motor-driven LK series, the VS type is offered on special request for viscosity and slurry applications; details are determined in consultation with the manufacturer.
Transfer pumps
In magnetic drive centrifugal pumps, the source viscosity limits are 2 for MDT, 30 for MD, MD-F, MD-V, and MEK, 100 for MMP, and 300 mPa·s for MP and MTFO; for dosing polymer solutions, selection moves beyond these series.
Selection Steps in Polymer Dosing
- Find out the viscosity: the viscosity (mPa·s) of the polymer solution at the dosing temperature. Manufacturer documentation and laboratory measurement provide this value; this page does not recommend a value.
- Calculate the flow rate: required L/h or mL/min and backpressure. Flow rate increases as pressure decreases, whereas in viscous fluid it drops; allow a margin.
- Match the series: Hicera V for mL/min and highly viscous fluid; diaphragm IX or EWN-R V type at the L/h level; G gear or LK at the L/min level.
- Select the control signal: 4-20 mA or pulse for dosing proportional to a flowmeter or process signal; IX, EWN-R, and EWP support these inputs; on the G gear pump, flow is adjusted proportional to speed via an inverter.
- Protect the line: strainer and relief valve on the G series; check valve and, if needed, pulsation dampener on diaphragm pumps; keeping the drain hole open on IX.
- Calibrate: with the viscous liquid under actual line conditions, reducing suction speed on the IX. For procedure steps, see dosing pump maintenance.
To monitor the concentration of fluorescently tagged polymer in cooling water, Pyxis fluorometers are used; this is the measurement of tagged polymer rather than flocculant dosing.
Frequently Asked Questions About Polymer Dosing Pumps
Series selection for viscous fluids, flow reduction, viscous valve, Hicera V, and chemical compatibility.
Which Iwaki pump is used for polymer dosing?
In Iwaki documentation, there are two products explicitly listed for polymer flocculants: the high-viscosity (V) type of EWN-R (polymer flocculant injection in wastewater treatment) and the Hicera V valveless plunger pump (polymer flocculant and slaked lime injection). IX-C and IX-D (up to 1,000 and 300 mPa·s) and the G series gear pump (0.5–10,000 mPa·s) are also specified for viscous fluids. The viscosity and flow rate of the polymer determine the selection.
Does pump flow rate drop in viscous fluids?
Yes. The IX catalog notes that discharge flow rate may decrease when pumping a viscous liquid and that a margin should be allowed during selection; the IX-B catalog gives this reduction as approximately 20 percent. For the V type of EWN-R, the catalog flow rate is measured with clean water, may vary depending on viscosity, and is not given as a fixed value. Therefore, flow rate in a viscous solution is verified by field calibration.
Is there a special valve for viscous liquids in the IX series?
Yes. According to the IX-B catalog, the allowable viscosity for IX-B015 and IX-B030 is 100 mPa·s with the standard valve and 1,000 mPa·s with the spring-loaded stainless steel viscous valve (special order); IX-B007 is specified for 1,000 mPa·s with the viscous valve only. IX-C pumps viscous fluids up to 1,000 mPa·s and IX-D up to 300 mPa·s as standard. For higher viscosities, consult the manufacturer.
Why does the Hicera V pump stand out for polymers?
With its valveless ceramic plunger design, Hicera V contains no suction or discharge valves; the manufacturer presents this as an advantage for metered transfer of viscous fluids and fluids prone to clogging. Its viscosity limit is 20,000 mPa·s; it is noted that discharge accuracy may decline at 500 mPa·s and above. Flow rates are small: AC-motor V-05 delivers 1.6–1.9 mL/min, while V-15 reaches up to 1,400–1,682 mL/min.
Is a magnetic drive centrifugal pump suitable for polymer dosing?
In Iwaki's magnetic drive centrifugal pumps, the source viscosity limits are low: MDT 2, MD, MD-F, and MD-V 30, MEK 30 (120 with application-specific approval), MMP 100, and MP and MTFO 300 mPa·s. Therefore, positive displacement series are evaluated for metered dosing of viscous polymer solutions. For transfer applications, see our magnetic drive pumps guide.
How is chemical compatibility determined for a polymer solution?
The EWN-R manual states that the pump has been evaluated with water and that suitability for liquids other than water rests with the user; wet-end materials are selected using a chemical compatibility table. This page does not specify polymer types, brands, or dosages; refer to the chemical compatibility chart and the polymer supplier's documentation.
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