Dispensing vs. Metering
When it comes to delivering precise amounts of liquid, there are two possible options: dispensing and metering. Every fluid management application...
2 min read
Blake Webb : 10/28/24 7:00 AM
Stuck deciding between Fluid Metering pumps and diaphragm pumps? While you may have seen both used in various industries, understanding the distinct differences between these two technologies can help you optimize performance, reduce maintenance costs, and ensure the reliability of your fluid handling systems.
Design Differences
Fluid Metering's rotating, reciprocating piston pumps are completely valveless and have only one moving part in their fluidic path to avoid clogging, seizures, downtime, and costly issues.
In comparison, diaphragm pumps rely on passive flapper valves for positive displacement. These pumps have internal inlet and exit valves that must function correctly for the system to maintain flow. Unfortunately, this makes diaphragm pumps prone to clogging, especially when handling fluids with particulates or crystallizing substances. For example, long, stringy particles can get caught in the valves, causing blockages. Pieces of the manifold system (usually plastic) and bottle cap piercings (in blood sample applications) are also known to get sucked into the diaphragm pump and stuck during its aspiration phase.
Functional Changes
While both pumps are equally pulsatile in their reciprocating nature, Fluid Metering's valveless piston design boasts the highest level of volumetric efficiency compared to competitor pumps including diaphragm pumps. It has a relatively flat flow rate curve with only a 2-4% flow rate difference regardless of back pressure. Conversely, diaphragm, peristaltic, and gear pumps can all see a 30-80% flow rate drop-off with increasing back pressure, resulting in less reliability and greater inconsistencies in performance.
Although both types of pumps have similar installation and integration requirements, valveless piston pumps often use stepper motors which offer higher reliability and torque. This becomes advantageous in applications requiring frequent on/off cycles.
Fluid Handling
Typically, diaphragm pump viscosity-handling capabilities are capped at around 150cPs. Fluid Metering pumps, however, are viscosity-independent, allowing them to handle a wide range of fluids - all the way up to highly viscous substances like peanut butter. This versatility makes them more suitable for a broader range of applications.
The material properties of the pump components also play a significant role in their performance with abrasive and corrosive fluids. Fluid Metering pumps feature chemically inert, dimensionally stable, and abrasion-resistant CeramPump® ceramics to handle aggressive and abrasive media without significant wear. In contrast, diaphragm pumps struggle with such fluids, often leading to premature failure.
Maintenance & Lifespan
Diaphragm pumps can require an annual predictive maintenance schedule which includes the replacement of passive flapper valves. This challenging task calls for additional field service charges, racking up the costs of an already inconvenient and pricey process. The diaphragm itself also tends to form cracks near the end of its life, leading to leaks, contamination, and inaccuracies. In contrast, Fluid Metering's valveless piston pumps are designed to run for millions of cycles, giving them the durability to last for the entire life of an OEM instrument, all the while maintaining 0.5% precision without maintenance or recalibration. This significantly reduces costs over time, especially in high-throughput applications.
Applied Advantages
Despite their common usage in many industries, diaphragm pumps are often bounded by their susceptibility to clogging and breakdowns. Valveless piston pumps excel beyond those limitations in many applications, including, but not limited to:
Diagnostics & IVD - dispensing reagents into microwells
Medical - cleaning and purging of pipetting devices; needle washing
Analytical - chromatography columns
While both diaphragm pumps and Fluid Metering's valveless piston pumps have taken their places in various settings, Fluid Metering's innovative designs consistently outperform in efficiency, precision, and long-term reliability, making them a superior choice for many industries. Ready to bypass the barriers and setbacks of diaphragm pumps? Contact our team of expert engineers today!
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