WALCHEM EWP-L & EWP-R Metering Pumps
The Walchem EWP Series, engineered by Iwaki and distributed under the Walchem brand, represents the next evolution of compact, high‑precision metering pumps for industrial water treatment. Built on a rugged IP66 platform and driven at 360 strokes per minute, the EWP delivers smooth, high‑resolution chemical feed with excellent priming and venting performance—even with challenging, off‑gassing chemicals.
Control Variants:
EWP‑L
The EWP‑L provides simple, dependable manual and external control with an 1800:1 turndown ratio. It is designed as a direct, modern replacement for the legacy EZ and EJ pumps, offering similar pricing but significantly expanded capability. For operators who prefer a straightforward interface, the two‑knob layout keeps adjustments intuitive while still supporting proportional analog and pulse control.
• Manual stroke rate control (0–100%)
• External proportional control: 4–20 mA or pulse input (0–6 Hz)
• Two‑knob interface (stroke rate + mode selector)
• Status LEDs (green = running, red = STOP input)
• STOP input (dry contact)
• Power: 100–240 VAC, 50/60 Hz
EWP‑R
The EWP‑R adds a full digital control platform with a backlit display, multicolor LED status indicator, advanced proportional modes, batch and interval batch control, alarm output, and an integrated 12 VDC power supply. It replaces the discontinued EWN‑R and provides a major upgrade in functionality without complicating installation or maintenance.
• Backlit LCD display
• Multicolor LED status indicator
• Expanded proportional control modes: ANA.P, ANA.V, PLS.V
• MULTI / DIV (×1–9999 / ÷1–9999)
• Batch and interval batch modes
• PRIME, AUX, Pre‑STOP, STOP, Interlock
• Alarm output (open collector)
• Keypad lockout
• Integrated 12 VDC auxiliary power
• Power: 100–240 VAC, 50/60 Hz
Compatibility With Legacy Walchem Pumps
One of the most important advantages of the EWP Series is its backward compatibility with Walchem’s long‑running E‑Series pumps.
• EWP‑L replaces EZ and EJ (EZ scheduled to end Spring 2026)
• EWP‑R replaces EWN‑R (no longer available)
• EWP‑Y will replace EWN‑Y (transition planned for late 2026)
• EWP pumps use the same liquid ends as EZ/EJ/EWN
• Most repair kits are shared, simplifying stocking and service
• Full model‑to‑model compatibility is documented on individual product pages
This makes the EWP Series a natural upgrade path for existing installations and a reliable long‑term platform for new systems.
Performance & Reliability
All EWP models share the same liquid‑end architecture used across the EZ, EJ, and EWN families. The high compression ratio improves priming and venting, especially with off‑gassing chemicals like sodium hypochlorite. The 360 spm drive provides high‑resolution feed and reduces slug dosing, while dual bearing support extends diaphragm life.
Installation & Mounting
The EWP Series is designed for fast, flexible installation. A removable mounting base supports both wall and surface mounting and allows tool‑free pump removal. A level, vibration‑free installation is recommended for best performance, and flooded suction is strongly advised when feeding off‑gassing chemicals.
Although the enclosure is IP66, the pump should be installed in a dry, sheltered location. It is not intended for direct outdoor exposure or operation while wet.
Material & Connection Options
The EWP Series offers a wide range of wet‑end materials—including PVC, GFRPP, PVDF, and 316 stainless steel—to support broad chemical compatibility. Tubing and threaded connection options are available depending on the model:
• 07 – 1/4" ID × 3/8" OD tubing
• 08 – 3/8" ID × 1/2" OD tubing
• 10 – 1/4" FNPT
• 11 – 1/2" MNPT
Tubing connections are typically used with flexible chemical feed tubing, while threaded NPT connections are preferred where rigid pipe or adapters are required.
Applications
The EWP Series is suitable for a wide range of industrial and commercial applications, including:
• Cooling towers
• Boilers
• Wastewater treatment
• Disinfection (NaOCl, PAA, etc.)
• pH/ORP control
• Industrial process dosing
• OEM skids and compact systems
Why the EWP Series Stands Out
The EWP Series combines Iwaki’s mechanical engineering with Walchem’s control and integration expertise. It offers:
• A clear upgrade path from legacy Walchem pumps
• High‑resolution feed at 360 spm
• Excellent priming and venting performance
• Broad material and connection options
• Rugged IP66 construction
• Flexible mounting and compact footprint
For installers, operators, and OEMs, the EWP Series delivers long‑term reliability, modern control capability, and seamless compatibility with the Walchem pumps already in the field.
