Walchem Metering Pumps: Choosing the Right Series for Your Chemical Dosing Application
When selecting a metering pump, required flow rate is only part of the equation. Pressure, chemical compatibility, control requirements, operating range, and the demands of the application can all determine which pump is the right fit.
Walchem offers several metering pump series designed for different chemical feed requirements. From straightforward low-flow dosing to automated, high-accuracy chemical delivery and higher-capacity motor-driven applications, understanding the differences between the EHE, EWP, EZ, LKN, and IX Series can make the selection process much easier.
Here is what separates these Walchem metering pump families and what to consider when choosing between them.
Start With Your Chemical Dosing Requirements
Before comparing pump series, it helps to define the application itself. At minimum, determine the chemical being pumped, required flow rate, discharge pressure, chemical concentration, operating temperature, available power, and how the pump needs to be controlled.
Flow and pressure are especially important because a pump's maximum flow and maximum pressure ratings should not be treated as if they necessarily occur at the same operating point. Walchem specifically notes that as selected flow output increases, a pump's pressure capability decreases. Manufacturer performance data should therefore be checked for the specific model and operating conditions.
Once these requirements are established, you can begin determining which Walchem series best matches the application.
Walchem EZ Series: Straightforward Chemical Metering
The EZ Series is a good place to start when an application calls for relatively straightforward chemical dosing without requiring extensive external control capabilities.
The EZ is an electronic metering pump with manual speed control adjustable up to 360 strokes per minute. Depending on the model, the series offers outputs up to 6.3 GPH and pressure capabilities up to 150 PSI. It also provides a 360:1 turndown ratio.
Its dual check-valve assemblies on both the suction and discharge sides are designed to support fast priming and reliable operation, while dual bearing support helps maintain proper axial movement and diaphragm life.
For applications where the operator primarily needs to set the desired feed rate at the pump, the EZ Series provides a relatively simple approach to controlled chemical dosing.
In short: Think of the EZ Series as the more straightforward choice for manual electronic metering when advanced process control isn't necessary.
Walchem EWP Series: Compact, High-Pressure Precision Dosing
The EWP Series steps up the pressure capability and control flexibility while maintaining a compact design.
EWP pumps provide flow rates up to 6.7 GPH and pressure capabilities up to 300 PSI. The series operates at up to 360 strokes per minute, allowing smaller quantities of chemical to be delivered more frequently for high-resolution chemical feed.
The pumps are housed in an IP66-rated enclosure and have a relatively small footprint, making the series well suited for installations where space or environmental protection is a consideration. Walchem also specifically positions the compact design for OEM integration.
The EWP family is available in different control configurations, including EWP-L and EWP-R models, allowing the pump to be matched more closely to the control requirements of the chemical feed system.
In short: Consider EWP when you need compact electronic metering, higher pressure capability, and greater control flexibility.
Walchem EHE Series: More Capacity With Versatile Control
Walchem describes the EHE as the “workhorse” of its E-Series, and its performance range helps explain why.
The EHE Series provides outputs up to 20 GPH and pressures up to 150 PSI, giving it substantially greater maximum flow capacity than the EZ and EWP families. It also offers a turndown ratio of up to 1800:1.
The EHE operates at up to 360 strokes per minute and incorporates microprocessor-based controls. Depending on configuration, control capabilities include manual speed adjustment, pulse input with multiplication or division, and programmable 4–20 mA input.
That combination makes the EHE useful when an application needs more capacity than the smaller electronic pumps while retaining precise control over chemical feed.
In short: EHE is a versatile choice when you need higher flow than the smaller E-Series pumps along with a wide operating range and process-control capabilities.
Walchem IX Series: Advanced Automated Chemical Dosing
For applications where precise control, automation, and a broad operating range are priorities, the IX Series takes a different approach.
Rather than using the conventional solenoid-driven design of the E-Series pumps, the IX is a digitally controlled, direct-drive diaphragm metering pump using a brushless DC motor.
Depending on the model, IX pumps range from very low feed rates up to approximately 80 GPH, with pressure capabilities reaching 247 PSI. Walchem specifies a turndown ratio of up to 1000:1, with motor control adjusting suction and discharge speeds to maintain accurate dosing across a broad range.
The IX Series also includes multiple control methods as standard, making it particularly useful for automated chemical feed systems where dosing may need to respond to external process conditions.
These capabilities make the IX well suited for applications ranging from water treatment to chemical processing where accuracy, automation, and flexibility are important.
In short: IX is the option to consider when the application requires sophisticated control, a very broad flow range, and highly accurate automated chemical delivery.
Walchem LKN Series: Motor-Driven Metering for Higher-Capacity Applications
The LKN Series stands apart from the electronic E-Series pumps.
LKN pumps are motor-driven, mechanically actuated diaphragm metering pumps designed for more demanding chemical-feed applications. The series provides capacities up to 114 GPH and pressures up to 225 PSI.
Instead of a solenoid, the pump uses a motor-driven system incorporating a dual-cam drive and worm gear reducer. Roller bearings and oil-bath lubrication are designed to provide durability during continuous operation.
Walchem identifies applications for the LKN family across water treatment, chemical processing, agriculture, mining, and paper processing. Different motor configurations are also available, including options intended for varying electrical and operating requirements.
For an application that has moved beyond lower-capacity electronic chemical feed and requires substantially greater output or continuous industrial service, the LKN Series provides another level of capability.
In short: Look toward the LKN Series when higher-capacity, motor-driven chemical metering is required.
So, Which Walchem Metering Pump Should You Choose?
The five series overlap in some areas, but they are designed to address different chemical-feed needs.
The EZ Series offers straightforward electronic dosing with manual adjustment. EWP combines a compact footprint with pressure capability up to 300 PSI. EHE increases capacity to as much as 20 GPH while providing flexible process controls. IX uses digitally controlled direct-drive technology for precise, highly automated dosing across a broad operating range. LKN moves into motor-driven metering for higher-capacity and demanding industrial applications.
However, the series alone does not determine the correct pump. Individual models within each family have different flow, pressure, liquid-end, connection, and material options.
Don't Forget Chemical Compatibility
Once you have narrowed down the appropriate series, the next step is choosing the correct configuration.
The liquid end and other wetted components need to be compatible with the chemical being dosed. Concentration, temperature, viscosity, and other fluid properties can affect which materials and configuration should be selected.
This is particularly important with aggressive chemicals. A pump may meet the application's flow and pressure requirements but still be unsuitable if its wetted materials are incompatible with the chemical.
Always verify chemical compatibility and the manufacturer's model-specific performance information before placing a pump into service.
Finding the Right Walchem Metering Pump
Choosing between the Walchem EZ, EWP, EHE, IX, and LKN Series becomes easier once you know what the application actually demands.
For a relatively simple chemical feed system, the EZ may provide everything necessary. An application requiring greater pressure or more control may point toward EWP. Higher-flow electronic metering may call for EHE, while IX provides an option for advanced automated dosing. Higher-capacity motor-driven applications may be better suited to LKN.
Pumping Solutions carries Walchem metering pumps and chemical feed equipment for a wide range of industrial and water treatment applications. If you're unsure which Walchem series or model fits your system, our team can help evaluate your chemical, required flow, pressure, materials, and control requirements to narrow down the appropriate pump.