Advanced Metering Pump Technology


Walchem and Iwaki combined their talents to design the most innovative and comprehensive metering pump product line in the world. With over 50 years of combined pump experience, the Iwaki-Walchem partnership leverages its strengths to exceed even the toughest customer expectations.

Committed to new product development, the products are innovative and revolutionary. A perfect example is the EK pump - the first waterproof IP67 metering pump in the world.


Featuring four great pump series, EZ, EW, EK and EHE, E-Class pumps are powered by advanced microprocessor-based electronics and superior mechanical design. With capacities up to 20 GPH and a maximum pressure rating of 215 PSI the E-Class has a pump that will fit any water treatment, municipal and industrial wastewater, agriculture, water conditioning, car wash or any other chemical feed application. And the entire E-Class pump line is backed with a comprehensive 2-year warranty that covers the entire pump, including the liquid end and diaphragm.

High Speed Performance

E-Class pumps operate at 360 strokes-per-minute. Most competitive products operate at 180 SPM or less resulting in slug feeding, accelerated diaphragm wear and poor feed control.

EZ Series

The EZ Series electronic metering pumps with microprocessor control offer precise chemical injection at a low cost. EZ pumps have outputs to 6.7 GPH and pressure capabilities to 150 PSI. The compact size and simple control make it ideal for OEM applications, water treatment, car wash and other industrial applications.

The EZ Series features an advanced microprocessor control with a turndown ratio of 360:1, making it an exceptional value. It is simple to operate with three pushbutton keys. The 360:1 turndown ratio provides unmatched versatility and results in high-resolution chemical feed and elimination of slug-feed effects.

Innovative Timer Control

The EZ-Timer module integrates Walchem's EZB pump technology with a versatile programmable timer. Timed feed control can be programmed in daily or weekly cycles. The weekly schedules can be programmed in either 1 or 2-week cycles with a daily on-time. The daily timer can be set for multiple daily on-times. The EZ-Timer pump is a simple and effective way to automate additions in small systems.

Dual Bearing Support

All E-Class pumps features dual bearing support. The armature and shaft are supported with a bearing on each end, which ensures proper axial movement, enabling the E-Class to operate at 360 SPM while extending the life of the diaphragm.

Superior Check Valve Performance

Dual Check Valve Assemblies in both suction and discharge fittings feature precision ball guides and tapered seats. Precise machining and molding of parts limit valve ball travel, ensuring that balls fully seat and seal with every stroke. This superior check valve design and performance guarantees fast priming.

High Compression Ratio

The compression ratio of a metering pump is important because it affects the pumps ability to prime and vent. The compression ratio is raised when you reduce the dead volume of the pump head during operation. All E-Class pumps feature a very high compression ratio that ensures proper feed especially with off-gassing products (i.e. Sodium Hyperchlorite).

EW Series

EW SeriesThe EW Series is the flagship of the E-Class with capacities up to 6.7 GPH (25.4 l/h) and a maximum pressure of 150 PSI (10 bar). Compact, powerful and packed with a variety of innovative design features the EW can enhance any feed application.

IP65 Construction

The rugged Polyphenylene Oxide (PPO) enclosure is equipped with a durable clear cover to protect the membrane switches and stroke control of the pump, which are mounted opposite the liquid end. The display utilizes a high temperature LCD that provides extra protection from sunlight in outdoor applications.

Control Features

All EW series pumps come equipped with pulse and stop input/output control. The EW Y module is loaded with:

  • Feed Accuracy - Powered by the E-Class 360 Stroke-Per-Minute technology the EW has an incredibly adjustment range of 1800:1 ensuring precise feed control for any application.
  • Analog Input Control - Fixed or scalable 4-20MA input control.
  • Pulse Input Control - Pulse input with multiply and divide features (1-9999). 12VDC output power supply for Hall Effect water meters.
  • Quick-Prime - Hold 2 keys down and pump runs at 100% of speed to prime quickly without adjusting application settings.
  • Feed Verification - The EW is equipped with 3-preprogrammed modes for accepting our Posiflow Feed Verification Sensor. The Posiflow provides a pulse feedback to the pump to verify prime and proper feed. Depending on the mode, the user can program to pump to stop, continue operating and/or send an alarm based on the Posiflow input.
  • Easy Draw-Down Calibration - In the calibration mode the user only needs to start and stop the pump, enter the draw-down volume and the pump calibrates volume-per-stroke.
  • Flow Display and Totalization - After calibration the EW will totalize the volume feed and display the flow rate. As long as stroke length is constant the pump will accurately totalize all feed. In cases where the pump is being controlled external with a pulse the pump will display and count down remaining flow based on the pulse input. Coupled with the Posiflow feed verification the EW is equipped to ensure proper feed to your application.
  • Keypad Lock-Out - Keypad functions can be locked out providing feed security, integrity and unwanted adjustments.

EK Series

The EK Series pumps are the world's first IP67 electronic metering pumps. This means that the EK is the only pump in the industry guaranteed to operate submerged 3 feet under water for up to 30 minutes!

Needless to say, the EK Series pumps are ideal for wet or high humidity environments such as irrigation, agriculture, car wash or paper mill applications. Capacity ratings are up to 6.7 GPH with a maximum pressure of 150 PSI.

IP67 Construction

By integrating the pump body into a one-piece design, sealing is easier and more effective. Both the drive and the controller are completely insulated from moisture or gas. Construction of the EK Series pumps make them perfect for indoor or outdoor applications where the pumps are frequently exposed to wash down.

Control Features

High speed and a 20% minimum stroke length allow the EK Series to achieve an 1800:1 turndown ratio. The digital display and pushbutton speed control make setting the EK pump easy and precise. The EK pumps come equipped with pulse input (1:1) control and also feature an external stop input that can be set to stop the pump from a normally open or normally closed contact.

EHE Series

The workhorse of the E-Class - no other electronic metering pump can match the power and performance of Walchem's EHE Series.

EHE pumps have outputs up to gallons per hour and pressure capabilities from 30 to 150 PSI. Combining the EHE performance and a turn-down ratio of 1800:1 yields one of the most versatile pumps on the market today.

Superior mechanical design and quality of manufacturing merge to create a pump better than the sum of its parts. The EHE Series is ideal for chemical feed applications in a wide range of fields, including water treatment, chemical process, municipal and industrial wastewater.


The EHE35 size pump is the most powerful electronic metering pump currently available. A pump's maximum pressure rating times its maximum output at that pressure gives a relative measure of the pump's hydraulic output power, a "power index".


Microprocessor-based circuitry provides the operator adjustment of pump speed and external input settings via a 4-button keypad. The EHE comes with digital and analog external mode control.

LK Series

In a class by itself - the LK is a motor driven, mechanically actuated diaphragm metering pump with a maximum capacity of 114 GPH (432 l/h) and maximum pressure of 225 PSI (1.5 MPa).

This expanded flow range makes the LK a perfect compliment to the E-Class Metering Pump Line.

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

Stroke Adjustment

Accurate and reliable stroke setting is accomplished with a micrometer dial of the spring back stroke adjustment mechanism. This lockable mechanism is adjustable from 10 to 100%.


The heart of the LK is the dual-cam drive with a built-in worm gear type speed reducer. This compact & rigid mechanism, provides maximum wear resistance in continuous operation over long periods of time.


All of the standard models employ totally enclosed fan-cooled motors which are vertically mounted to save space. A variety of motor options are available, including explosion- proof, and DC variable speed motors for external control by a 4-20 mA input signal.

More articles on this topic

Lewa´s New Micro-Metering Pump with Mechatronic Control

08.04.2015 -

When testing new small-scale process technologies in high-pressure laboratories, maximum precision is required so that later upscaling will be as accurate as possible. To be able to work safely and without spillages at pressures up to 500 bar, Lewa GmbH has developed a hermetically sealed high-pressure micro-metering pump.

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