Precision Piston Pumps for Liquid Dispensing
FOREACH EA precision piston pumps use a stepper motor to drive the piston back and forth, controlling liquid aspiration and metered dispensing through piston travel. Nominal capacities range from 50 μL to 20 mL for reagent addition, sample dilution and other liquid-handling tasks in clinical chemistry analyzers, immunoassay analyzers and laboratory automation equipment. Estimated service life is 5 million cycles with pure water at ambient temperature and 50 kPa backpressure.
Pump head options include PMMA, PCTG and PEEK, with ceramic, PEEK or sapphire pistons. Integrated pump-valve assemblies and OEM customization are available. Pump heads, pistons, fluid connections, motors, valve assemblies and controllers can be configured to suit the reagent, dispensing sequence and available installation space for integration into an instrument's liquid-handling module.
Watch the EA piston pump overview
What Should You Specify for a Liquid-Dispensing Piston Pump?
Use the product overview as a starting point, then define the dispensing task. The following selection notes explain how to compare a pump specification with the requirements of an installed liquid path.
Working dose and cycle time
Record the minimum, normal and maximum dose, the time allowed for aspiration and dispensing, and any refill interval. A capacity that covers the largest transfer still needs evaluation at the smallest critical dose.Accuracy and repeatability
Accuracy describes closeness to the target; repeatability describes the spread of repeated results. Define separate acceptance limits and compare results obtained at the same volume and operating conditions.Complete wetted path
Check the pump head, piston, seals, valves, tubing and outlet against the reagent and cleaning method. A compatible pump head alone does not establish compatibility of the complete assembly.
Does Piston Pump Capacity Define the Minimum Dispensing Volume?
No. Full-stroke capacity and theoretical volume per motor step describe displacement and command resolution. Delivered liquid can differ because of mechanical backlash, valve timing, trapped gas, tubing expansion and droplet release. These effects become more significant when they occupy a larger fraction of a short stroke.
Choose a capacity that covers the required transfer sequence while leaving the smallest dose practical to validate. Read the specified test volume and test conditions alongside any accuracy or repeatability figure. Full-stroke performance should not be applied to every partial stroke, and a small command increment is not a validated minimum dose.
Understand piston pump accuracy, repeatability and resolution
Why Do Priming and Valve Timing Change Piston Pump Delivery?
A bubble compresses as pressure rises, so part of the piston displacement can initially compress gas instead of moving liquid through the outlet. Flexible tubing can also store and release volume as pressure changes. A repeatable motor command may therefore produce delayed or inconsistent liquid delivery.
Prime the complete path using the procedure appropriate to the selected assembly. Check inlet sealing, reservoir level, valve switching and the time allowed for pressure to settle. Evaluate startup and steady operation separately, particularly after a reservoir change, cleaning cycle or long idle period.
How Should a Piston Pump Be Validated in an Instrument?
Test the minimum, normal and maximum working volumes using the intended reagent or a justified representative fluid. Include the production valves, tubing, fittings and dispense tip; record fluid temperature, inlet conditions, backpressure, motion settings and cycle timing. Measure mean delivery and variation separately rather than judging one successful dispense.
Review material compatibility and performance again after representative cleaning and operating cycles. The EA configurations linked below provide concrete capacity and pump-head options to compare. Use each selected model's current specification and confirm the installed result before applying a general product-overview claim to your instrument.
Compare EA Piston Pump Capacities and Head Materials
Start with the representative EA configurations below, then compare capacity, head material, connections and control requirements on the product pages. Models with the same capacity may serve different material requirements; they are not automatically interchangeable in the same reagent path.