When it comes to delivering exact amounts of liquid, two primary methods are available: dispensing and metering. Each fluid management application requires a tailored approach.
Image Credit: Fluid Metering, Inc.
Understanding the differences between these techniques is essential to achieving optimal results. The following is a breakdown of the key distinguishing features of each function.
Key Terms:
- Dispensing: Delivering individual doses of liquid.
- Dosing: Providing multiple doses simultaneously, which requires several motor rotations.
- Transferring: Moving a specified volume of liquid over a set time when speed is not critical; the motor pauses in between.
- Metering: Controlling the flow rate, where speed is essential; the motor operates continuously without stopping.
While the distinction between dispensing and dosing can be somewhat subjective, Fluid Metering defines these functions as follows:
Primary Purpose:
Dispensing:
- Ideal for delivering a specific volume of fluid in discrete quantities.
- Applications: Filling containers, vials, or test tubes with precise amounts (e.g., dispensing reagents into microwells).
Metering:
- Maintains a continuous flow rate (volume over time).
- Applications: Chemical dosing, pH adjustment (e.g., continuous water treatment or industrial processes, the delivery of sheath fluid in flow cytometry, or the circulation of water and sodium bicarbonate in dialysis machines).
Flow Rate Control:
Dispensing allows for accurate control of flow rates during intermittent dosing, making it ideal for situations that require low to moderate flow. In contrast, metering provides a steady flow rate, making it suitable for larger-scale industrial operations.
Controlling Metering Speed:
While pump heads remain unchanged, motors can be swapped. Customers can opt for faster brushless DC motors for long-term applications (approximately 2,000 rpm) or stepper motors with speed limitations (approximately 700-800 rpm).
The pump head can also be optimized based on pulsation or viscosity, with slower speeds recommended for viscous liquids.
Fluid Types and Materials:
Every Fluid Metering pump is a hybrid and can function interchangeably for dispensing or metering, thanks to stepper motors that enable precise starting and stopping. Each includes automatic dosing control, Fluid Metering’s innovative valveless design, and CeramPump® technology to handle acids, bases, viscous liquids, and slurries.
Making Informed Decisions:
Dosing and metering functions are precise and applicable across various contexts. For continuous flow rate control over extended periods, metering is the preferred solution. Conversely, for delivering specific volumes independent of flow speed, dispensing is more suitable.
About Fluid Metering, Inc.
Fluid Metering, Inc. (FMI) is a worldwide leader in life science pumps and dispensers, having pioneered the first valve-less piston pump over 64 years ago. With specialized expertise in fluidics and applications, Fluid Metering, Inc. supports instrument developers in tackling complex fluidic challenges.
Committed to innovation through collaboration, Fluid Metering, Inc. advances health, sustainability, and quality of life. ISO 9001:2015 certified.
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