Walchem

WALCHEM EWP SERIES METERING PUMPS

Precise Dosing. Dependable Performance. Flexible Controls.
High‑accuracy chemical metering pumps for industrial water treatment and process dosing.

The Walchem EWP Series, manufactured by Iwaki (Japan) and distributed under the Walchem brand, is a next‑generation family of solenoid‑driven metering pumps designed for precise chemical dosing in industrial water treatment and process applications. All standard models operate at 360 strokes per minute, feature a high compression ratio for reliable priming and venting, and are housed in a rugged IP66‑rated enclosure. The series includes two control platforms—EWP‑L and EWP‑R—built on the same mechanical drive and liquid‑end architecture.

Why Choose the EWP Series?

The EWP Series combines Iwaki’s mechanical engineering with Walchem’s control and integration expertise.

• Successor platform to multiple legacy Walchem E-Series pumps
• High‑resolution feed at 360 spm
• Excellent priming and venting performance
• Wide turndown ratio
• Rugged IP66 enclosure
• Flexible mounting options
• Broad material compatibility
• Engineered for longevity and durability

Performance Range:

• Maximum flow: 6.7 GPH (25 L/h)
• Minimum flow: 0.4 GPH (25 mL/min)
• Maximum pressure: 300 PSI (20 bar)
• Stroke rate: 360 spm
• Turndown ratio: 1800:1
• High compression ratio improves priming and venting, especially with off‑gassing chemicals

Electrical Specifications:

Power Supply: 100–240 VAC, 50/60 Hz
Average Power: 13 W (A/B heads), 23 W (C–F heads)
Max Current (115 VAC): 0.8 A / 1.1 A
Max Current (230 VAC): 0.4 A / 0.5 A
Auxiliary Power (EWP‑R only): 12 VDC, 30 mA
Shipping Weight: ~7 lbs (plastic heads), ~9 lbs (SS heads)

Control Variants:

EWP‑L (Simple Function Type)

• 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 (Standard Type)

• 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

Key Engineering Features:

• High compression ratio for reliable priming and venting
• Dual bearing support for long diaphragm life
• Dual check valve assemblies with precision ball guides
• Rugged IP66 enclosure (dust‑tight, water‑resistant)
• Compact footprint suitable for cabinets and OEM skids

Liquid End & Material Options:

Pump Head Materials: PVC (VC, VE, VF), GFRPP (PC, PE, PA), PVDF (TC, TA, FC), 316SS (SH)
Valve Balls: Alumina ceramic (CE), PTFE (VF), PCTFE (PA, TA), Hastelloy C276 (SH)
Valve Seats: FKM, EPDM, AFLAS, 316SS (SH)
Diaphragm: PCTFE bonded to EPDM (all models)
Gasket: PTFE (all models)

Connection Types:

07 – Tubing, 1/4" ID × 3/8" OD
08 – Tubing, 3/8" ID × 1/2" OD
10 – Threaded, 1/4" FNPT
11 – Threaded, 1/2" MNPT

Note:
The EWP Series supports both tubing connections (for flexible chemical feed tubing) and threaded NPT connections (for rigid pipe or adapters). Specific suction/discharge geometries vary by wet‑end material and are detailed on individual product pages.

Special Options Available:

A – Auto Degassing Valve (B/C/D sizes, VC/VE)
F – 1st‑Gen AAW Installed (−40 PSI derate)
H – High Pressure (up to 290 PSI)
K – No Manual Air Valve (SH only)
M – Multi‑Function Valve (not for FC/SH)
12 – Adds ADV‑VCH‑7 to TC pumps
W – High Pressure + No Manual Air Valve (SH only)
N – No special options

Applications:

• Cooling towers
• Boilers
• Wastewater treatment
• Disinfection (NaOCl, PAA, etc.)
• pH/ORP control
• Industrial process dosing
• OEM skids and compact systems

Installation & Mounting:

• Removable secondary base supports wall or surface mounting
• Tool‑free pump removal
• Install level for accurate dosing
• Requires a solid, vibration‑free foundation
• IP66 enclosure protects against spray, but pump must be kept dry
• Not intended for direct outdoor exposure
• Flooded suction recommended for off‑gassing chemicals

Legacy Model Replacement & Cross‑Series Compatibility Details:

Walchem (Iwaki) is transitioning several legacy metering pump families to the EWP platform beginning in 2026.

EWP‑L replaces:
• EZ Series (scheduled end: Spring 2026)
• EJ Series
• Uses the same liquid ends as EZ/EJ/EWN
• Similar pricing with expanded features
• Shares most repair kits with legacy models

EWP‑R replaces:
• EWN‑R (no longer available)

EWP‑Y will replace:
• EWN‑Y (transition planned for late 2026)

Full model‑to‑model compatibility is documented on individual product pages.

EHE is the workhorse of the E Series metering pumps. Superior mechanical design and quality of manufacturing merge to create a pump greater than the sum of its parts. EHE pumps have outputs up to 20 GPH (76 l/h) and a maximum pressure of 150 PSI (10 bar). Combining the EHE performance with a turndown ratio of 1800:1 yields one of the most versatile pumps on the market today. EHE Series is ideal for chemical feed applications in a wide range of fields, including drinking water, agriculture, and municipal/industrial wastewater.

The EH-HV Series is specifically designed to accurately feed high viscosity chemicals.  Equipped with machined PVC liquid ends and spring loaded stainless steel valve balls, the HV series is designed for superior valve action and performance.

The EJ Series provide precise chemical injection at an economical price. Universal voltage capability enables operation from 100 - 240 VAC in virtually all countries. The EJ Series are compact, simple to operate and have outputs to 1.3 GPH (4.8 LPH) and a maximum pressure of 175 PSI (1.2 MPa). The EJ Series operate at 360 strokes-per-minute, providing high resolution chemical feed and high turndown capability. Most competitive products operate at slower speeds, resulting in slug feeding, accelerated diaphragm wear and poor feed control.

The EK Series pump is the world’s first and only IP67 rated electronic metering pump - guaranteed to operate submerged 3 feet under water for up to 30 minutes! This makes the EK Series pumps ideal for wet or high humidity environments found in irrigation, agriculture, food & beverage, car wash or paper mill applications.

The EK Series are highly precise metering pumps with outputs to 6.7 GPH (25.2 l/h) and a maximum pressure of 150 PSI (10 bar). The 360 stroke-per-minute operation results in high-resolution chemical feed and long service life. Quiet and compact, EK pumps prime in seconds and hold prime reliably.

The EWN-R Series electronic metering pumps offer superior high speed dosing capability with more standard features. The flexibility of the EWN-R pump enable it be integrated into virtually any chemical feed application using a universal-voltage, digital controller with an expanded set of control features. Superb valve performance and advanced solenoid engineering combine to make a highly precise pump for the most demanding applications. EWN pumps have outputs to 6.7 GPH (25.2 L/h) and a maximum pressure of 290 PSI (20 bar). The high speed of operation results in high resolution chemical feed and long service life. Quiet and compact, the EWN pumps prime in seconds and hold prime reliably.

Iwaki’s New EWN-Y Series Electromagnetic metering pump with the revolutionary EFS Flow Sensor provides precise flow monitoring, feedback and control. The new EWN-Y electromagnetic pump combined with EFS flow sensor provides accurate real-time control and display of dosing rate. Set point control allows the desired flow rate to be simply programmed into the pump. Through feedback from the EFS sensor, the pump constantly adjusts its speed to maintain the set dosing rate - even under changing temperature, viscosity or suction and discharge pressure conditions. The EFS is mounted directly on the pump for accurate dosing rate measurement - ALL WITHOUT ANY TIME-CONSUMING CALIBRATION.

EZ Series with digital speed control offers precise chemical injection at a low cost. EZ has output capacities up to 6.3 GPH (23.8 l/h) and a maximum pressure of 150 PSI (10 bar). The compact size and simple control make it ideal for OEM, water treatment, car wash and a variety of other applications.

Simply stated - the EZ packs all of the 360spm performance of the bigger pumps into the compact chassis of the industry’s easiest pump to operate. The EZ is the best on/off pump on the market. Built to prime, hold prime and to last, the EZ Series metering pump offers precise chemical injection at an economical cost. Features include double ball check valves, long lasting diaphragm, an optional automatic air vent valve and the ability to remotely mount the control unit.

A new class of advanced metering pumps! Iwaki’s IX Series are digitally controlled direct-drive diaphragm pumps. Years of experience in high-end motor technology result in extremely accurate and energy efficient metering pumps with high resolution. The IX Series meet today’s demand for automated chemical delivery in industries from water treatment to chemical process. Highly precise control offers a solution for a variety of dosing applications.

The LK Series metering pump is the largest in the high performance line of pumps from Walchem. The LK is a motor-driven, mechanically actuated diaphragm metering pump with a maximum capacity of 114 GPH (432 l/h) and a maximum pressure of 225 PSI (1.5 MPa). The heart of the LK is a compact and very reliable dual-cam system drive and worm gear reducer. Roller bearings and oil bath lubrication ensure outstanding durability and wear resistance in continuous operation.

The LK Series is ideal for chemical feed applications in a wide range of fields, including water treatment, chemical process, agriculture, mining and paper.

Walchem Chemical Metering Pump Kits, Repair Parts, Accessories, Motors, Pulsation Dampeners, Flow Meters, Head & Drive Assemblies, Valve Cartridges & Pump Systems. We have all of your Walchem Chemical Feed & Dosing Pump Parts for sales online including O-rings, Valves, Nuts, Springs, Connectors, Gaskets, Seal Rings, Washers, Screws Fittings & Tubing. Look no further for your Walchem Replacement part needs... we even have Diaphragms, Foot Valves, Housings Knobs and Spacers! Get your EHE, EJ, EK, EWN, EZ, IX, LKN Series Parts on PumpCatalog.com

Walchem Boiler Accessories

Walchem offers a variety of products you need to complete the installation of your boiler blowdown controllers. For less demanding installations, the solenoid valves and orifice unions may be used. For greater flexibility and reliability, the motorized ball valves and flow control needle valves are employed.

Flow Control Valves Our flow control four-V port globe valves are equipped with a micrometer dial and pointer which enables the valve to set within 1/100th of a turn of the handwheel. This allows you to fine tune the blowdown flow rate. In the event that the valve becomes clogged, it may be opened to allow the debris to pass, and then returned to the original position.

Motorized Ball Valves The motorized ball valves deliver a torque of 150 in-lbs, using a non-reversing motor, opening the valve in 5 seconds, minimizing pressure hammer. The motor is protected in a NEMA 4X enclosure, and features an integral thermal overload protector with automatic reset. Repair kits are available as well.

Solenoid Valves These valves open when the coil is energized, and close when de-energized. When the coil is energized, the pilot valve opens, relieving the pressure above the piston, which is lifted from its seat by the laminar plunger. When de-energized, a spring closes the pilot valve and opens a bleed passageway to permit pressure to build above the piston and seat it. No differential pressure is required to open the valve.

Walchem WBL/WCM Boiler Controllers

Ever worry about those nasty chemicals that you're heating up leaking into the condensate lines and eating up your boiler? Worrying never helped anything, but installation of a condensate monitor will! The WCM Series controller will keep a watchful eye on the conductivity of the condensate and divert the flow away from your boiler if it gets too high. A small price to pay for peace of mind!

Our WCM Series control the conductivity of a boiler's condensate and the WDC Series can control the condensate of two boilers (within 500 ft.). All of Walchem's Boiler Water and Condensate Monitors are micro-processor-based with an easy-to-use menu format for programming. UL/SA/CE certified. 

• Walchem offers four different Boiler Water Controllers and Condensate Monitors. The WBL Series controls conductivity blowdown/chemical feed for one boiler and the WDB Series controls two boilers within 500 feet of each other.

Cooling Tower Pump Controllers

The WCT300 is a single tower, feed/bleed, conductivity controller and the WCT310 adds a programmable dual biocide output option. All Walchem cooling tower controllers are microprocessor-based with an easy-to-use menu format for programming. Features include water meter inputs with flow totalizer, optional 4-20mA output(s) and conductivity-based biocide additions. UL/CSA/CE certified.

Walchem WDB / WDC Boiler Controllers

Ever worry about those nasty chemicals that you're heating up leaking into the condensate lines and eating up your boiler? Worrying never helped anything, but installation of a condensate monitor will! The WCM Series controller will keep a watchful eye on the conductivity of the condensate and divert the flow away from your boiler if it gets too high. A small price to pay for peace of mind!

Our WCM Series control the conductivity of a boiler's condensate and the WDC Series can control the condensate of two boilers (within 500 ft.). All of Walchem's Boiler Water and Condensate Monitors are micro-processor-based with an easy-to-use menu format for programming. UL/SA/CE certified.

• Walchem offers four different Boiler Water Controllers and Condensate Monitors. The WBL Series controls conductivity blowdown/chemical feed for one boiler and the WDB Series controls two boilers within 500 feet of each other.

Dual Input PH/ ORP Controllers

Walchem’s pH/ORP on-line process controllers will improve your treatment performance. The WDP Series is a microprocessor-based system which features user-friendly menu programming for improved versatility and multiple performance options. WDP controllers have earned a strong reputation in the field for ease of use and long-term reliability. UL/CSA/CE certified.

Dual Input Cooling Tower Controllers

Walchem offers a variety of on-line controllers for cooling tower applications. The WDT300/310 is a dual input system designed to control conductivity for two independent towers. The WDT300 Series is equipped to control conductivity, pH (or ORP) and programmable dual biocide outputs. The WDT and WCT Series are both microprocessor-based controllers with user-friendly programming. UL/CSA/CE certified.

With 4 conductivity inputs, up to 4 boilers may be controlled using either continuous sampling, or intermittent (timed) sampling. In intermittent sampling, the sample is checked with the valve closed, eliminating flashing to ensure that the conductivity reading is correct. Blowdown based upon that sample may be for a set amount of time, or a for a time that varies depending upon how far from the set point the reading is. Two-stage intermittent sampling is also available, allowing the user to test the boiler less frequently during times of the day when loading is not as high. 

Eight relays provide blowdown, plus either chemical feed or alarm capability. It can also be equipped with eight (8) analog inputs and six (6) digital inputs capable of monitoring tank levels, providing interlocks, feed verification and receiving other plant parameter signals such as steam load, phosphate concentration, etc.

NEMA 4X packaging and UL/CSA/CE approvals ensure that the WebMaster can withstand the toughest industrial environment.

• The WMB series WebMaster can be configured for your specific boiler application.

PH/ ORP Sensors

Walchem’s WEL Series electrodes are cost-effective differential pH and ORP sensors for industrial applications. The WEL Series features a convenient modular design with a durable CPVC housing. The cartridge uses an interlocking connection and double o-ring seal to insure watertight fit and secure seating. The electrode is designed for an in-line or submersed universal mounting style. UL/CSA/CE certified.

PH/ ORP Controllers

Walchem’s WPH Series controllers feature the same microprocessor technology and intuitive programming as the WDP Series. WPH controllers are designed for versatile output configurations which allow programming of up to four different outputs via one control unit. The WPH and WDP systems offer a choice between mechanical relay outputs or direct pulse proportional control. UL/CSA/CE certified.

Internet Based PH/ ORP Control

WebMaster GI combines Walchem's industrial pH/ORP and conductivity product lines with the WebMaster communications platform. WebMaster GI can advance your RO/DI, wastewater or pre-treatment system into the 21st century. WebMaster GI can be configured for a number of different applications. The four inputs can be any arrangement of pH, ORP, contacting or toroidal conductivity.
Lots of inputs/Outputs and the flexibility of mapping, makes WebMaster GI a perfect solution for applications for water treatment, wastewater treatment, metal finishing and an array of other applications.